http://www.who.int/influenza/gisrs_laboratory/updates/summaryreport/en/index.html

Influenza virus activity in the world

13 May 2013

Based on FluNet reporting (as of 7 May 2013, 10:30 UTC), during weeks 16 to 17 (14 to 27 April 2013), National Influenza Centres (NICs) and other national influenza laboratories from 80 countries, areas or territories reported data. The WHO GISRS laboratories tested more than 41 698 specimens. 4384 were positive for influenza viruses, of which 2400 (54.7%) were typed as influenza A and 1984 (45.3%) as influenza B. Of the sub-typed influenza A viruses, 1224 (67.3%) were influenza A(H1N1)pdm09, 595 (32.7%) were influenza A(H3N2). Of the characterized B viruses, 91 (85%) belonged to the B-Yamagata lineage and 16 (15%) to the B-Victoria lineage.

Summary

During weeks 16 and 17, A(H1N1)pdm09 viruses were predominant globally followed by A(H3N2) and influenza B viruses. Influenza activity remained low in the northern and southern hemisphere.

In Europe and North America, laboratory confirmed detections of influenza B viruses decreased compared to previous weeks. Overall, influenza activity remained low.

In Asia influenza activity was low. In the eastern parts of Asia, A(H3N2) and A(H1N1)pdm09 viruses were detected, while in the southern parts in general, co-circulation of A(H1N1)pdm09 and influenza B viruses were reported.

Influenza A(H1N1)pdm09 and influenza B viruses co-circulated at low levels in the African region.

Sporadic influenza activity of all three circulating subtypes was reported from Oceania.

Sporadic activity of influenza A(H1N1)pdm09 and A(H3N2) remained in Central and South America.

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Other analyses

• Click here to see real-time FluNet charts
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• Click here to see real-time FluNet data for the most recent reporting week

http://www.cdc.gov/flu/weekly/

Synopsis:

During week 18 (April 28-May 4, 2013), influenza activity remained low in the United States.

• Viral Surveillance: Of 3,048 specimens tested and reported by collaborating laboratories, 125 (4.1%) were positive for influenza.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
• Influenza-Associated Pediatric Deaths: One pediatric death was reported.
• Influenza-Associated Hospitalizations: A cumulative rate for the season of 44.2 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. Of reported hospitalizations, 50% were among adults 65 years and older.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 0.9%. This is below the national baseline of 2.2%. All 10 regions reported ILI below region-specific baseline levels. 49 states and New York City experienced minimal activity, and the District of Columbia and 1 state had insufficient data.
• Geographic Spread of Influenza: 5 states reported regional influenza activity; 3 states reported local influenza activity; Guam, Puerto Rico, and 37 states reported sporadic influenza activity; 5 states reported no influenza activity, and the District of Columbia and the U.S. Virgin Islands did not report.

A description of surveillance methods is available at: http://www.cdc.gov/flu/weekly/overview.htm

*HHS regions (Region 1 CT, ME, MA, NH, RI, VT; Region 2: NJ, NY, Puerto Rico, US Virgin Islands; Region 3: DE, DC, MD, PA, VA, WV; Region 4: AL, FL, GA, KY, MS, NC, SC, TN; Region 5: IL, IN, MI, MN, OH, WI; Region 6: AR, LA, NM, OK, TX; Region 7: IA, KS, MO, NE; Region 8: CO, MT, ND, SD, UT, WY; Region 9: AZ, CA, Guam, HI, NV; and Region 10: AK, ID, OR, WA).
† Elevated means the % of visits for ILI is at or above the national or region-specific baseline
‡ National data are for current week; regional data are for the most recent three weeks
§ Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

U.S. Virologic Surveillance

U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories located in all 50 states and Puerto Rico report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza virus type and influenza A virus subtype.

Region specific data can be found at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation

Antigenic Characterization

CDC has antigenically characterized 2,354 influenza viruses [234 2009 H1N1 viruses, 1,305 influenza A (H3N2) viruses, and 815 influenza B viruses] collected by U.S. laboratories since October 1, 2012.

2009 H1N1 [234]:

• 231 (98.7%) of the 234 2009 H1N1 viruses tested were characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2012-2013 influenza vaccine for the Northern Hemisphere.
• 3 (1.3%) of the 234 2009 H1N1 viruses tested showed reduced titers with antiserum produced against A/California/7/2009.

Influenza A (H3N2) [1,305]:

• 1,300 (99.6%) of the 1,305 H3N2 influenza viruses tested have been characterized as A/Victoria/361/2011-like, the influenza A (H3N2) component of the 2012-2013 Northern Hemisphere influenza vaccine.
• 5 (0.4%) of the 1,305 H3N2 viruses tested showed reduced titers with antiserum produced against A/Victoria/361/2011.

Influenza B (B/Yamagata/16/88 and B/Victoria/02/87 lineages) [815]:

• Yamagata Lineage [546]: 546 (67.0%) of the 815 influenza B viruses tested so far this season have been characterized as B/Wisconsin/1/2010-like, the influenza B component of the 2012-2013 Northern Hemisphere influenza vaccine.

• Victoria Lineage [269]: 269 (33.0%) of 815 influenza B viruses tested have been from the B/Victoria lineage of viruses.

Composition of the 2013-2014 Influenza Vaccine

The World Health Organization (WHO) has recommended vaccine viruses for the 2013-2014 Northern Hemisphere vaccines, and the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) has made recommendations for the composition of the 2013-2014 influenza vaccines to be used in the United States. Both agencies recommend that trivalent vaccines contain an A/California/7/2009-like (2009 H1N1) virus, an A(H3N2) virus antigenically like the cell-propagated, or cell-grown, virus A/Victoria/361/2011 (A/Texas/50/2012), and a B/Massachusetts/2/2012-like (B/Yamagata lineage) virus. It is recommended that quadrivalent vaccines containing an additional influenza B virus contain a B/Brisbane/60/2008-like (B/Victoria lineage) virus in addition to the viruses recommended for the trivalent vaccines. These recommendations were based on global influenza virus surveillance data related to epidemiology and antigenic characteristics, serological responses to 2012-2013 seasonal vaccines, and the availability of candidate strains and reagents.

Antiviral Resistance

Testing of 2009 H1N1, influenza A (H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir and zanamivir) is performed at CDC using a functional assay. Additional 2009 influenza A (H1N1) clinical samples are tested for a single mutation in the neuraminidase of the virus known to confer oseltamivir resistance (H275Y). The data summarized below combine the results of both testing methods. These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with antiviral-resistant virus.

High levels of resistance to the adamantanes (amantadine and rimantadine) persist among 2009 influenza A (H1N1) and A (H3N2) viruses (the adamantanes are not effective against influenza B viruses). As a result, data from adamantane resistance testing are not presented below.

The majority of currently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir and zanamivir; however, rare sporadic cases of oseltamivir-resistant 2009 H1N1 and A (H3N2) viruses have been detected worldwide. Antiviral treatment with oseltamivir or zanamivir as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at greater risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at http://www.cdc.gov/flu/antivirals/index.htm.

Novel Influenza A Virus

No new human infections with novel influenza A viruses in the United States were reported to CDC during week 18.

On April 1, 2013, the World Health Organization (WHO) first reported 3 human infections with a new influenza A (H7N9) virus in China. Since then, additional cases have been reported. Most reported cases have severe respiratory illness and, in some cases, have died. At this time, no cases of H7N9 outside of China have been reported. The new H7N9 virus has not been detected in people or birds in the United States.

Pneumonia and Influenza (P&I) Mortality Surveillance

During week 18, 7.0% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.2% for week 18.

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Influenza-Associated Pediatric Mortality

One influenza-associated pediatric death was reported to CDC during week 18. This death was associated with an influenza A virus for which the subtype was not determined and occurred during week 6 (week ending February 9, 2013).

A total of 138 influenza-associated pediatric deaths have been reported during the 2012-2013 season from Chicago [2], New York City [4] and 37 states (AL [1], AR [4], AZ [4], CA [4], CO [5], FL [8], GA [2], HI [2], IA [1], IL [2], IN [4], KS [2], KY [2], LA [2], MA [4], MD [3], ME [1], MI [6], MN [4], MS [1], NE [1], NH [3], NJ [7], NM [3], NV [3], NY [10], OH [4], OK [1], PA [1], SC [5], SD [3], TN [3], TX [17], UT [3], VA [1], WA [1], and WI [4]).

Additional data can be found at http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

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Influenza-Associated Hospitalizations

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).

The FluSurv-NET covers more than 80 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; and IA, MI, OH, RI, and UT during the 2012-2013 season.

Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.

Between October 1, 2012 and April 30, 2013, 12,330 laboratory-confirmed influenza-associated hospitalizations were reported. This is a rate of 44.2 per 100,000 population. The most affected group is those ≥65 years, accounting for about 50% of reported cases. Among all hospitalizations, 9,760 (79.2%) were associated with influenza A and 2,490 (20.2%) with influenza B. There was no virus type information for 46 (0.4%) hospitalizations. Among hospitalizations with influenza A subtype information, 3,697 (96.1%) were attributed to H3 and 143 (3.7%) were attributed to 2009 H1N1. The most commonly reported underlying medical conditions among hospitalized adults were cardiovascular disease, metabolic disorders, obesity, and chronic lung disease (excluding asthma). The most commonly reported underlying medical conditions in hospitalized children were asthma, neurologic disorders, obesity, and immune suppression. Approximately 46% of hospitalized children had no identified underlying medical conditions. Among 657 hospitalized women of childbearing age (15-44 years), 199 were pregnant, including 7 pregnancies among the 34 pediatric cases in this category.

Additional FluSurv-NET data can be found at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.

The current season’s influenza-associated hospitalization data includes patients admitted from October 1, 2012 through April 30, 2013; however, these data will continue to be updated as additional information is received.

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Outpatient Illness Surveillance

Nationwide during week 18, 0.9% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.2%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)

Region specific data is available at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation

On a regional level, the percentage of outpatient visits for ILI ranged from 0.5% to 1.5% during week 18. All 10 regions reported a proportion of outpatient visits for ILI below their region-specific baseline levels.

ILINet Activity Indicator Map

Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during spring and fall weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.

During week 18, the following ILI activity levels were experienced:

• Forty-nine states and New York City experienced minimal ILI activity (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• Data were insufficient to calculate an ILI activity level for the District of Columbia and 1 state (South Dakota).

*This map uses the proportion of outpatient visits to health care providers for influenza-like illness to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
Data collected in ILINet may disproportionately represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state.
Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map are based on reports from state and territorial epidemiologists. The data presented in this map is preliminary and may change as more data is received.
Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses, but does not measure the severity of influenza activity.

During week 18, the following influenza activity was reported:

• Five states reported regional influenza activity (Connecticut, Hawaii, Maine, Massachusetts, and New York).
• Three states reported local influenza activity (Alaska, Ohio, and Pennsylvania).
• Guam, Puerto Rico, and 37 states reported sporadic influenza activity (Alabama, Arizona, Arkansas, California, Colorado, Delaware, Florida, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, North Carolina, North Dakota, Oklahoma, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• Five states (Georgia, Idaho, Kansas, Mississippi, and Utah) reported no influenza activity.
• The U.S. Virgin Islands and the District of Columbia did not report.

Flu Activity data in XML Format | View Full Screen

http://www.euroflu.org/cgi-files/bulletin_v2.cgi

Summary, week 18/2013

Consultation rates for influenza-like illness (ILI) and acute respiratory infection (ARI) are at low levels in all countries. The percentages of sentinel samples from ILI, ARI, and severe acute respiratory infection (SARI) surveillance that tested positive for influenza were low. Influenza B was detected in most of the positive specimens collected in week 18/2013, although most virus detections since the start of the season have been influenza A. Countries with hospital-based sentinel surveillance continue to report SARI hospitalizations, although numbers are declining overall, as is the proportion of samples testing positive for influenza.

http://www.cdc.gov/flu/about/season/flu-season-2013-2014.htm

What sort of flu season is expected this year?

Flu seasons are unpredictable in a number of ways. Although epidemics of flu happen every year, the timing, severity, and length of the season varies from one year to another.

Will new strains of flu circulate this season?

Flu viruses are constantly changing so it’s not unusual for new flu virus strains to appear each year. For more information about how flu viruses change, visit How the Flu Virus Can Change.

When will flu activity begin and when will it peak?

The timing of flu is very unpredictable and can vary from season to season. Flu activity most commonly peaks in the U.S. in January or February. However, seasonal flu activity can begin as early as October and continue to occur as late as May.

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What should I do to prepare for this flu season?

CDC recommends a yearly flu vaccine for everyone 6 months of age and older as the first and most important step in protecting against this serious disease. While there are many different flu viruses, the flu vaccine is designed to protect against the three main flu strains that research indicates will cause the most illness during the flu season. Getting the flu vaccine as soon as it becomes available each year is always a good idea, and the protection you get from vaccination will last throughout the flu season.

In addition, you can take everyday preventive steps like staying away from sick people and washing your hands to reduce the spread of germs. If you are sick with flu, stay home from work or school to prevent spreading influenza to others.

Where can I get a flu vaccine?

Flu vaccines are offered in many locations, including doctor’s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools.

Even if you don’t have a regular doctor or nurse, you can get a flu vaccine somewhere else, like a health department, pharmacy, urgent care clinic, and often your school, college health center, or work.

Visit the HealthMap Vaccine Finder to locate where you can get a flu shot.

What kind of vaccines will be available in the United States for 2013-2014?

A number of different manufacturers produce trivalent (three component) influenza vaccines for the U.S. market, including intramuscular (IM), intradermal, and nasal spray vaccines. See Key Facts About Seasonal Flu Vaccine for more information about the different types of vaccine available in the United States.

Most of the flu vaccine offered for the 2013-2014 season will be trivalent (three component). Some seasonal flu vaccines will be formulated to protect against four flu viruses (quadrivalent flu vaccines) and will be available as well according to manufacturers. All nasal spray vaccines are expected to be quadrivalent, however, this makes up only a small portion of total vaccine availability.

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What flu viruses does this season’s vaccine protect against?

Flu vaccines are designed to protect against three influenza viruses that experts predict will be the most common during the upcoming season. Three kinds of influenza viruses commonly circulate among people today: Influenza A (H1N1) viruses, influenza A (H3N2) viruses, and influenza B viruses,. Each year, one flu virus of each kind is used to produce seasonal influenza vaccine.

The 2013-2014 trivalent influenza vaccine is made from the following three viruses:

• an A/California/7/2009 (H1N1)pdm09-like virus;
• an A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011;
• a B/Massachusetts/2/2012-like virus.

It is recommended that quadrivalent vaccines containing two influenza B viruses contain the above three viruses and a B/Brisbane/60/2008-like virus.

More information about influenza vaccines is available at Preventing Seasonal Flu With Vaccination.

How effective is the flu vaccine?

Inactivated influenza vaccine effectiveness (VE) can vary from year to year and among different age and risk groups. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work?

How long does a flu vaccine protect me from getting the flu?

Multiple studies conducted over different seasons and across vaccine types and influenza virus subtypes have shown that the body’s immunity to influenza viruses (acquired either through natural infection or vaccination) declines over time. The decline in antibodies is influenced by several factors, including the antigen used in the vaccine, age of the person being vaccinated, and the person’s general health (for example, certain chronic health conditions may have an impact on immunity). When most healthy people with regular immune systems are vaccinated, their bodies produce antibodies and they are protected throughout the flu season, even as antibody levels decline over time. People with weakened immune systems may not generate the same amount of antibodies after vaccination; further, their antibody levels may drop more quickly when compared to healthy people.

For everyone, getting vaccinated each year provides the best protection against influenza throughout flu season. It’s important to get a flu vaccine every year, even if you got vaccinated the season before and the viruses in the vaccine have not changed for the current season.

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Will this season’s vaccine be a good match for circulating viruses?

It’s not possible to predict with certainty which flu viruses will predominate during a given season. Flu viruses are constantly changing (called drift) – they can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time. (For more information about the vaccine virus selection process visit Selecting the Viruses in the Influenza (Flu) Vaccine.) Because of these factors, there is always the possibility of a less than optimal match between circulating viruses and the viruses in the vaccine.

How do we know if there is a good match between the vaccine viruses and those causing illness?

Over the course of a flu season, CDC studies samples of flu viruses circulating during that season to evaluate how close a match there is between viruses used to make the vaccine and circulating viruses. Data are published in the weekly FluView.

In addition, CDC conducts studies each year to determine how well the vaccine protects against illness.

Can the vaccine provide protection even if the vaccine is not a “good” match?

Yes, antibodies made in response to vaccination with one flu virus can sometimes provide protection against different but related viruses. A less than ideal match may result in reduced vaccine effectiveness against the virus that is different from what is in the vaccine, but it can still provide some protection against influenza illness.

In addition, it’s important to remember that the flu vaccine contains three virus viruses so that even when there is a less than ideal match or lower effectiveness against one virus, the vaccine may protect against the other viruses.

For these reasons, even during seasons when there is a less than ideal match, CDC continues to recommend flu vaccination. This is particularly important for people at high risk for serious flu complications, and their close contacts.

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What will CDC do to monitor vaccine effectiveness for the 2013-2014 season?

CDC carries out and collaborates with other partners within and outside CDC to assess how well flu vaccines work. During the 2013-2014 season, CDC is planning multiple studies on the effectiveness of both the flu shot and the nasal-spray flu vaccine. These studies will measure vaccine effectiveness in preventing laboratory confirmed influenza among persons aged 6 months and older, since beginning in the 2010-2011 season the Advisory Committee on Immunization Practices (ACIP) recommended annual vaccination for everyone in this age group.

Where can I find information about vaccine supply?

Information about vaccine supply is available on the CDC influenza web site.

Is there treatment for the flu?

Yes. If you get sick, there are drugs that can treat flu illness. They are called antiviral drugs and they can make your illness milder and make you feel better faster. They also can prevent serious flu-related complications, like pneumonia. For more information about antiviral drugs, visit Treatment (Antiviral Drugs).

What is antiviral resistance?

Antiviral resistance means that a virus has changed in such a way that the antiviral drug is less effective in treating or preventing illness. Samples of viruses collected from around the United States and worldwide are studied to determine if they are resistant to any of the FDA-approved influenza antiviral drugs.

What will CDC do to monitor antiviral resistance in the United States during the 2013-2014 season?

CDC routinely collects viruses through a domestic and global surveillance system to monitor for changes in influenza viruses. CDC will continue ongoing surveillance and testing of influenza viruses. Additionally, CDC is working with the state public health departments and the World Health Organization to collect additional information on antiviral resistance in the United States and worldwide. The information collected will assist in making informed public health policy recommendations.

http://www.cdc.gov/flu/weekly/index.htm?s_cid=seasonalflu-govd-003

2012-2013 Influenza Season Week 16 ending April 20, 2013

All data are preliminary and may change as more reports are received.

Synopsis:

During week 16 (April 14-20, 2013), influenza activity decreased in the United States.

• Viral Surveillance: Of 3,384 specimens tested and reported by collaborating laboratories, 250 (7.4%) were positive for influenza.
• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the epidemic threshold.
• Influenza-Associated Pediatric Deaths: Five pediatric deaths were reported.
• Influenza-Associated Hospitalizations: A cumulative rate for the season of 43.9 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. Of reported hospitalizations, 50% were among adults 65 years and older.
• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.1%. This is below the national baseline of 2.2%. All 10 regions reported ILI below region-specific baseline levels. One state experienced low activity; 49 states and New York City experienced minimal activity, and the District of Columbia had insufficient data.
• Geographic Spread of Influenza: Three states reported widespread influenza activity; 3 states reported regional influenza activity; 8 states reported local influenza activity; the District of Columbia, Guam, Puerto Rico, and 35 states reported sporadic influenza activity; 1 state reported no influenza activity, and the U.S. Virgin Islands did not report.

A description of surveillance methods is available at: http://www.cdc.gov/flu/weekly/overview.htm

*HHS regions (Region 1 CT, ME, MA, NH, RI, VT; Region 2: NJ, NY, Puerto Rico, US Virgin Islands; Region 3: DE, DC, MD, PA, VA, WV; Region 4: AL, FL, GA, KY, MS, NC, SC, TN; Region 5: IL, IN, MI, MN, OH, WI; Region 6: AR, LA, NM, OK, TX; Region 7: IA, KS, MO, NE; Region 8: CO, MT, ND, SD, UT, WY; Region 9: AZ, CA, Guam, HI, NV; and Region 10: AK, ID, OR, WA).
† Elevated means the % of visits for ILI is at or above the national or region-specific baseline
‡ National data are for current week; regional data are for the most recent three weeks
§ Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

U.S. Virologic Surveillance

U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories located in all 50 states and Puerto Rico report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza virus type and influenza A virus subtype.

Region specific data can be found at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation

Antigenic Characterization

CDC has antigenically characterized 2,209 influenza viruses [210 2009 H1N1 viruses, 1,264 influenza A (H3N2) viruses, and 735 influenza B viruses] collected by U.S. laboratories since October 1, 2012.

2009 H1N1 [210]:

• 207 (98.6%) of the 210 2009 H1N1 viruses tested were characterized as A/California/7/2009-like, the influenza A (H1N1) component of the 2012-2013 influenza vaccine for the Northern Hemisphere.
• 3 (1.4%) of the 210 2009 H1N1 viruses tested showed reduced titers with antiserum produced against A/California/7/2009.

Influenza A (H3N2) [1,264]:

• 1,260 (99.7%) of the 1,264 H3N2 influenza viruses tested have been characterized as A/Victoria/361/2011-like, the influenza A (H3N2) component of the 2012-2013 Northern Hemisphere influenza vaccine.
• 4 (0.3%) of the 1,264 H3N2 viruses tested showed reduced titers with antiserum produced against A/Victoria/361/2011.

Influenza B (B/Yamagata/16/88 and B/Victoria/02/87 lineages) [735]:

• Yamagata Lineage [494]: 494 (67.2%) of the 735 influenza B viruses tested so far this season have been characterized as B/Wisconsin/1/2010-like, the influenza B component of the 2012-2013 Northern Hemisphere influenza vaccine.

• Victoria Lineage [241]: 241 (32.8%) of 735 influenza B viruses tested have been from the B/Victoria lineage of viruses.

Composition of the 2013-2014 Influenza Vaccine

The World Health Organization (WHO) has recommended vaccine viruses for the 2013-2014 Northern Hemisphere vaccines, and the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) has made recommendations for the composition of the 2013-2014 influenza vaccines to be used in the United States. Both agencies recommend that trivalent vaccines contain an A/California/7/2009-like (2009 H1N1) virus, an A(H3N2) virus antigenically like the cell-propagated, or cell-grown, virus A/Victoria/361/2011 (A/Texas/50/2012), and a B/Massachusetts/2/2012-like (B/Yamagata lineage) virus. It is recommended that quadrivalent vaccines containing an additional influenza B virus contain a B/Brisbane/60/2008-like (B/Victoria lineage) virus in addition to the viruses recommended for the trivalent vaccines. These recommendations were based on global influenza virus surveillance data related to epidemiology and antigenic characteristics, serological responses to 2012-2013 seasonal vaccines, and the availability of candidate strains and reagents.

Antiviral Resistance

Testing of 2009 H1N1, influenza A (H3N2), and influenza B virus isolates for resistance to neuraminidase inhibitors (oseltamivir and zanamivir) is performed at CDC using a functional assay. Additional 2009 influenza A (H1N1) clinical samples are tested for a single mutation in the neuraminidase of the virus known to confer oseltamivir resistance (H275Y). The data summarized below combine the results of both testing methods. These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with antiviral-resistant virus.

High levels of resistance to the adamantanes (amantadine and rimantadine) persist among 2009 influenza A (H1N1) and A (H3N2) viruses (the adamantanes are not effective against influenza B viruses). As a result, data from adamantane resistance testing are not presented below.

The majority of currently circulating influenza viruses are susceptible to the neuraminidase inhibitor antiviral medications, oseltamivir and zanamivir; however, rare sporadic cases of oseltamivir-resistant 2009 H1N1 and A (H3N2) viruses have been detected worldwide. Antiviral treatment with oseltamivir or zanamivir as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at greater risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at http://www.cdc.gov/flu/antivirals/index.htm.

Novel Influenza A Virus

No new human infections with novel influenza A viruses in the United States were reported to CDC during week 16.

On April 1, 2013, the World Health Organization (WHO) first reported 3 human infections with a new influenza A (H7N9) virus in China. Since then, additional cases have been reported. Most reported cases have severe respiratory illness and, in some cases, have died. At this time, no cases of H7N9 outside of China have been reported. The new H7N9 virus has not been detected in people or birds in the United States.

Pneumonia and Influenza (P&I) Mortality Surveillance

During week 16, 6.7% of all deaths reported through the 122 Cities Mortality Reporting System were due to P&I. This percentage was below the epidemic threshold of 7.3% for week 16.

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Influenza-Associated Pediatric Mortality

Five influenza-associated pediatric deaths were reported to CDC during week 16. One death was associated with an influenza A virus for which the subtype was not determined and occurred during week 16 (week ending April 13, 2013) and four deaths were associated with influenza B viruses and occurred during weeks 3, 13, 14, and 15 (weeks ending January 19, March 30, April 6, and April 13, 2013).

A total of 131 influenza-associated pediatric deaths have been reported during the 2012-2013 season from Chicago [1], New York City [4] and 37 states (AL [1], AR [4], AZ [3], CA [4], CO [5], FL [8], GA [2], HI [2], IA [1], IL [1], IN [4], KS [2], KY [2], LA [2], MA [4], MD [3], ME [1], MI [6], MN [4], MS [1], NE [1], NH [3], NJ [7], NM [3], NV [1], NY [9], OH [4], OK [1], PA [1], SC [4], SD [3], TN [3], TX [17], UT [3], VA [1], WA [1], and WI [4]).

Additional data can be found at http://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

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Influenza-Associated Hospitalizations

The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in children younger than 18 years of age (since the 2003-2004 influenza season) and adults (since the 2005-2006 influenza season).

The FluSurv-NET covers more than 80 counties in the 10 Emerging Infections Program (EIP) states (CA, CO, CT, GA, MD, MN, NM, NY, OR, TN) and additional Influenza Hospitalization Surveillance Project (IHSP) states. The IHSP began during the 2009-2010 season to enhance surveillance during the 2009 H1N1 pandemic. IHSP sites included IA, ID, MI, OK and SD during the 2009-2010 season; ID, MI, OH, OK, RI, and UT during the 2010-2011 season; MI, OH, RI, and UT during the 2011-2012 season; and IA, MI, OH, RI, and UT during the 2012-2013 season.

Data gathered are used to estimate age-specific hospitalization rates on a weekly basis, and describe characteristics of persons hospitalized with severe influenza illness. The rates provided are likely to be an underestimate as influenza-related hospitalizations can be missed, either because testing is not performed, or because cases may be attributed to other causes of pneumonia or other common influenza-related complications.

Between October 1, 2012 and April 13, 2013, 12,250 laboratory-confirmed influenza-associated hospitalizations were reported. This is a rate of 43.9 per 100,000 population. The most affected group is those ≥65 years, accounting for 50% of reported cases. Among all hospitalizations, 9,729 (79.4%) were associated with influenza A and 2,439 (19.9%) with influenza B. There was no virus type information for 44 (0.4%) hospitalizations. Among hospitalizations with influenza A subtype information, 3,575 (96.1%) were attributed to H3 and 136 (3.7%) were attributed to 2009 H1N1. The most commonly reported underlying medical conditions among hospitalized adults were cardiovascular disease, metabolic disorders, obesity, and chronic lung disease (excluding asthma). The most commonly reported underlying medical conditions in hospitalized children were asthma, neurologic disorders, and immune suppression. Approximately 44% of hospitalized children had no identified underlying medical conditions. Among 572 hospitalized women of childbearing age (15-44 years), 175 were pregnant, including 7 pregnancies among the 33 pediatric cases in this category.

Additional FluSurv-NET data can be found at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.

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Outpatient Illness Surveillance

Nationwide during week 16, 1.1% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.2%. (ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)

Region specific data is available at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

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On a regional level, the percentage of outpatient visits for ILI ranged from 0.4% to 2.0% during week 16. All 10 regions reported a proportion of outpatient visits for ILI below their region-specific baseline levels.

ILINet Activity Indicator Map

Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during spring and fall weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.

During week 16, the following ILI activity levels were experienced:

• One state experienced low ILI activity (Vermont).
• Forty-nine states and New York City experienced minimal ILI activity (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming).
• Data were insufficient to calculate an ILI activity level for the District of Columbia.

*This map uses the proportion of outpatient visits to health care providers for influenza-like illness to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
Data collected in ILINet may disproportionately represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state.
Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map are based on reports from state and territorial epidemiologists. The data presented in this map is preliminary and may change as more data is received.
Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses, but does not measure the severity of influenza activity.

During week 16, the following influenza activity was reported:

• Widespread influenza activity was reported by 3 states (Connecticut, Massachusetts, and New York).
• Regional influenza activity was reported by 3 states (New Hampshire, New Jersey, and Pennsylvania).
• Local influenza activity was reported by 8 states (Alaska, Arizona, Louisiana, Maine, Michigan, Ohio, Oklahoma, and Virginia).
• The District of Columbia, Guam , Puerto Rico, and 35 states reported sporadic influenza activity (Alabama, Arkansas, California, Colorado, Delaware, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Mexico, North Carolina, North Dakota, Oregon, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming).
• One state (Georgia) reported no influenza activity.
• The U.S. Virgin Islands did not report.

Additional National and International Influenza Surveillance Information

FluView Interactive: This season, FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm.

  http://www.euroflu.org/cgi-files/bulletin_v2.cgi

Summary, week 14/2013

Consultation rates have decreased in most countries of the Region. The number of specimens tested from both sentinel and non-sentinel sources and the percentage of influenza-positive specimens have decreased. The number of hospitalizations due to severe acute respiratory infection (SARI) has been decreasing in line with a decrease in the proportion of influenza-positive specimens. In week 14/2013, influenza B viruses represented the majority of influenza detections from sentinel and non-sentinel sites in the Region. For information about human infections with avian influenza A(H7N9) virus in China please click here .

http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/apr1013china.html

China eyes birds as H7N9 source as human cases rise to 33

Lisa Schnirring Staff Writer

Apr 10, 2013 (CIDRAP News) – “Five more H7N9 influenza infections have been confirmed in eastern China, all in older adults, while suspicions grow that wild birds may be the source and that the disease might be spreading to people through poultry environments.

Newly reported cases include two women from Shanghai, two men from Jiangsu province, and a man from Zhejiang province, according to separate reports today from Hong Kong’s Centre for Health Protection (CHP). The illnesses boost China’s number of infections with the new virus to 33, with the number of deaths holding steady at 9………..”

http://www.who.int/csr/don/2013_04_09/en/index.html

Human infection with influenza A(H7N9) virus in China – update

9 April 2013 -As of 9 April 2013 (14:00 CET), the National Health and Family Planning Commission notified WHO of an additional three laboratory-confirmed cases of human infection with influenza A(H7N9) virus.

The latest laboratory-confirmed cases include two patients from Jiangsu – an 85 -year-old man who became ill on 28 March 2013 and a 25-year-old pregnant woman who became ill on 30 March 2013. Both are in severe condition. The third patient is a 64-year-old man from Shanghai who became ill on 1 April 2013, and died on 7 April 2013.

To date, a total of 24 cases have been laboratory confirmed with influenza A(H7N9) virus in China, including seven deaths, 14 severe cases and three mild cases.

More than 600 close contacts of the confirmed cases are being closely monitored. In Jiangsu, investigation is ongoing into a contact of an earlier confirmed case who developed symptoms of illness.

The Chinese government is actively investigating this event and has heightened disease surveillance. Retrospective testing of recently reported cases with severe respiratory infection may uncover additional cases that were previously unrecognized. An inter-government task force has been formally established, with the National Health and Family Planning Commission leading the coordination along with the Ministry of Agriculture and other key ministries. The animal health sector has intensified investigations into the possible sources and reservoirs of the virus.

WHO is in contact with national authorities and is following the event closely. The WHO-coordinated international response is also focusing on work with WHO Collaborating Centres for Reference and Research on Influenza and other partners to ensure that information is available and that materials are developed for diagnosis and treatment and vaccine development. No vaccine is currently available for this subtype of the influenza virus. Preliminary test results provided by the WHO Collaborating Centre in China suggest that the virus is susceptible to the neuraminidase inhibitors (oseltamivir and zanamivir).

At this time there is no evidence of ongoing human-to-human transmission.

WHO does not advise special screening at points of entry with regard to this event, nor does it recommend that any travel or trade restrictions be applied.

http://www.who.int/csr/don/2013_04_07/en/index.html

Human infection with influenza A(H7N9) virus in China – update

7 April 2013 -As of 7 April 2013 (16:30 CET), the Chinese health authorities notified WHO of an additional three laboratory-confirmed cases of human infection with influenza A(H7N9) virus.

The first patient is a 59-year-old man resident of Shanghai, who became ill on 25 March 2013, and is now in critical condition. The second patient is a 55-year-old man from Anhui who became ill on 28 March 2013, and is now in stable condition. The third patient is a 67-year-old man from Shanghai who became ill on 29 March 2013, and is considered a mild case.

To date, a total of 21 cases have been laboratory confirmed with influenza A(H7N9) virus in China, including six deaths, 12 severe cases and three mild cases.

More than 530 close contacts of the confirmed cases are being closely monitored. In Jiangsu, investigation is ongoing into a contact of an earlier confirmed case who developed symptoms of illness.

The Chinese government is actively investigating this event and has heightened disease surveillance. Retrospective testing of recently reported cases with severe respiratory infection may uncover additional cases that were previously unrecognized. An inter-government task force has been formally established, with the National Health and Family Planning Commission leading the coordination along with the Ministry of Agriculture and other key ministries. The animal health sector has intensified investigations into the possible sources and reservoirs of the virus.

WHO is in contact with national authorities and is following the event closely. The WHO-coordinated international response is also focusing on work with WHO Collaborating Centres for Reference and Research on Influenza and other partners to ensure that information is available and that materials are developed for diagnosis and treatment and vaccine development. No vaccine is currently available for this subtype of the influenza virus. Preliminary test results provided by the WHO Collaborating Centre in China suggest that the virus is susceptible to the neuraminidase inhibitors (oseltamivir and zanamivir).

At this time there is no evidence of ongoing human-to-human transmission.

WHO does not advise special screening at points of entry with regard to this event, nor does it recommend that any travel or trade restrictions be applied.