May 14th, 2013
posted by Paul Rega, MD, FACEP May 14, 2013 @ 8:17 am
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Self-Reported Increased Confusion or Memory Loss and Associated Functional Difficulties Among Adults Aged ≥60 Years — 21 States, 2011
May 10, 2013 / 62(18);347-350
Declines in cognitive function vary among persons and can include changes in attention, memory, learning, executive function, and language capabilities that negatively affect quality of life, personal relationships, and the capacity for making informed decisions about health care and other matters (1). Memory problems typically are one of the first warning signs of cognitive decline, and mild cognitive impairment might be present when memory problems are greater than normal for a person’s age but not as severe as problems experienced with Alzheimer’s disease (2,3). Some, but not all, persons with mild cognitive impairment develop Alzheimer’s disease; others can recover from mild cognitive impairment if certain causes (e.g., medication side effects or depression) are detected and treated (3). In 2012, the U.S. Department of Health and Human Services published the National Plan to Address Alzheimer’s Disease, calling for expanding data collection and surveillance efforts to track the prevalence and impact of Alzheimer’s and other types of dementia (4). To estimate the prevalence of self-reported increased confusion or memory loss and associated functional difficulties among adults aged ≥60 years, CDC analyzed data from 21 states that administered an optional module in the 2011 Behavioral Risk Factor Surveillance System (BRFSS) survey. The results indicated that 12.7% of respondents reported increased confusion or memory loss in the preceding 12 months. Among those reporting increased confusion or memory loss, 35.2% reported experiencing functional difficulties. These results provide baseline information about the number of noninstitutionalized older adults with increased confusion or memory loss that is causing functional difficulties and might require services and supports now or in the future.
BRFSS consists of annual state-based telephone surveys of randomly selected noninstitutionalized U.S. adults aged ≥18 years regarding health practices and risk behaviors linked to chronic diseases, injuries, and preventable infectious diseases.* In 2011, all 50 states and the District of Columbia conducted the BRFSS survey by landline and cellular telephones, and the median survey response rate was 49.7%. In 2011, 21 states† included a 10-question optional cognitive impairment module§ in their BRFSS surveys. Because only seven of the 21 states conducted cell phone interviews in addition to landline telephone interviews, this analysis was restricted to landline respondents aged ≥60 years from the 21 states.¶ The median landline response rate among the 21 states was 53.4%, and the rates ranged from 37.4% in California to 66.0% in Nebraska.** This analysis was further limited to the 59,852 adults aged ≥60 years with nonmissing responses to the first question in the module.
Respondents who answered affirmatively to the question, “During the past 12 months, have you experienced confusion or memory loss that is happening more often or is getting worse?” were categorized as reporting increased confusion or memory loss. Functional difficulties were identified among these persons if they responded, “always,” “usually,” or “sometimes” to one of two questions about whether confusion or memory loss interfered with their “ability to work, volunteer, or engage in social activities,” or caused them to “give up household activities or chores” that they “used to do.” Additional questions addressed the need for assistance, getting care or assistance from a family member or friend, and discussing increased confusion or memory loss with a health-care provider. Respondents who declined to answer, had a missing answer, or who answered “don’t know/not sure” were excluded from the analyses involving those variables.
Respondents were categorized by age group, sex, race/
ethnicity,†† education level, disability status,§§ veteran status, and employment status. BRFSS landline weights were used to adjust for the probability of selection and to reflect the total adult population in each state by age group, race/ethnicity, education level, marital status, and home ownership status. To account for the complex sampling design, weighted data were analyzed using statistical software.
In 2011, 12.7% of respondents reported increased confusion or memory loss during the preceding 12 months, and 35.2% of those persons reported functional difficulties (Table 1). The percentage reporting confusion or memory loss was significantly higher among the following: persons aged ≥85 years (15.6%) compared with those aged 60–64 years (12.0%) and 65–74 years (11.9%); Hispanics or Latinos (16.9%) compared with whites (12.1%); persons with less than a high school education (16.2%) compared with persons with more education; persons who reported they were disabled (20.2%) compared with persons who were not disabled (7.5%); and persons who were unable to work (28.3%) compared with those who were employed (7.8%), unemployed (16.4%), homemakers (11.8%), students (3.9%), and retirees (12.3%) (Table 1).
Among those reporting increased confusion or memory loss, significant differences in the percentage with functional difficulties were found among the same demographic groups, although in some cases the patterns differed. For example, the percentage with functional difficulties was significantly higher among adults aged 60–64 years (44.7%) compared with 65–74 years (29.0%) and 75–84 years (32.6%) and among blacks or African Americans (61.6%) compared with whites (29.1%) and Asians/Native Hawaiians or Other Pacific Islanders (16.2%) (Table 1). By state, the percentage reporting increased confusion or memory loss ranged from 6.4% in Tennessee to 20.0% in Arkansas. Among those with increased confusion or memory loss, the percentage with functional difficulties ranged from 21.3% in Wisconsin to 52.2% in West Virginia (Table 2).
Among persons reporting increased confusion or memory loss, those with functional difficulties were significantly more likely than those without functional difficulties to report needing help (81.0% compared with 38.2%), getting help from a family member or friend (46.5% compared with 6.0%), and discussing their increased confusion or memory loss with a health-care provider (32.6% compared with 12.1%). In addition, those who reported functional difficulties were more likely to report being unable to work (32.8% compared with 9.6%) (Table 3).
Age is the best-known risk factor for Alzheimer’s disease (the most common cause of dementia), and more than 90% of cases occur in persons aged ≥60 years (2). Research shows that Alzheimer’s disease causes changes in the brain years and even decades before the first symptoms appear, and a better understanding about normal age-related cognitive decline could provide important insights for future prevention efforts (1,2). A systematic review found that among the primary care populations studied, as many as 66% of all dementia cases were undiagnosed, with the majority of missed cases classified as mild to moderate (5). Missed or delayed diagnosis impedes the ability to identify and intervene for treatable causes and to provide timely and accurate information and resources to patients and their families.
Public health surveillance provides the ability to track and monitor trends and identify health disparities to understand the magnitude of the problem, plan for future resource and service needs, inform interventions, and guide research efforts. However, public health surveillance of dementia is limited and complicated by methodologic challenges associated with identifying cases in the community (6). For these reasons, one suggestion is that public health surveillance of these conditions be broadly focused and address outcomes related to functional impairment rather than etiology (6). BRFSS provides an opportunity to respond to the national call for expanded surveillance efforts by tracking self-reported confusion or memory loss that is currently causing functional difficulties among noninstitutionalized adults and could progress to a more serious state of impairment.
The BRFSS results for 21 states described in this report indicate that 12.7% of persons aged ≥60 years report increased confusion or memory loss in the preceding year, and among these persons, 35.2% report functional difficulties. The findings show that increased confusion or memory loss generally increased with age, but the percentage reporting functional difficulties among persons aged 60-64 years was as great as among persons aged ≥85 years and greater than among persons aged 65–84. These findings suggest a need for future studies to examine the relationship of age and functional difficulties caused by increased confusion or memory loss. For example, younger persons might face challenges obtaining diagnostic testing because health-care professionals might not suspect symptoms, or access to employer-sponsored benefits could be placed in jeopardy if employed persons lose their jobs or are unable to work (7).
Among persons reporting functional difficulties, only 32.6% report discussing their symptoms with a health-care provider. Early and accurate diagnosis provides opportunities for individuals and families to initiate financial planning, develop advance directives, enroll in clinical trials and anticipate care needs. Some causes for cognitive decline are reversible (e.g., depression, infections, medication side effects, or nutritional deficiencies), but they can be serious and should be treated by a health-care provider as soon as possible (2). Misperceptions about dementia-related conditions might lead to delayed diagnosis (4), and understanding cultural beliefs and public perception is important for meeting national goals for increasing awareness. For example, studies conducted with diverse groups of older adults found that terminology used to describe brain health and beliefs about cognition varied among racial/ethnic populations (9). Increased confusion or memory loss and functional difficulties were reported among all racial/ethnic groups in this analysis, with persons identifying themselves as black or African American reporting the highest levels of functional difficulties compared with other groups.
Among those reporting increased confusion or memory loss and functional difficulties, 81.0% report needing assistance, and only 46.5% report getting help from a family member or friend. The need for care could precede or follow a diagnosis of dementia and escalates over time (8). Care could be provided by family members and friends or through paid services. Understanding who is at risk for requiring care now or in the future can help with anticipating needs and associated costs.
Wide variation observed among the 21 states might be the result of different cultural or other factors and indicates the importance of state-based data on this subject. Understanding cultural and social contexts is important when communicating public health messages (8). Future studies of state-specific data examining associations between increased confusion or memory loss and potential risk factors for dementia such as cardiovascular disease, diabetes, depression, or physical inactivity (3) might provide more insights that could also help explain the variations observed across states.
The findings in this report are subject to at least five limitations. First, data are self-reported, not validated by any clinical measurement, and might be subject to recall bias. Second, the survey design is cross-sectional, and causality of specific diseases or conditions cannot be inferred. Third, although questions underwent multiple rounds of cognitive testing to ensure that respondents understood the questions, given misperceptions surrounding dementia (4,7,8), respondents might provide the most “socially acceptable” answer, which could vary by race/ethnicity or geography, and could account in part for the variability observed among states. For example, blacks or African Americans might be less likely than whites to report cognitive decline (10). Furthermore, whether increased confusion or memory loss interferes with a respondent’s ability to accurately describe functional difficulties is unknown. Fourth, these results might underestimate confusion or memory loss and functional difficulties because BRFSS does not include residents of nursing homes or other facilities where a high percentage of people with cognitive impairment reside, and results were limited to landline telephone survey responses and did not include cell phone respondents. Finally, response rates among the 21 states were low and varied widely, ranging from 37.4% to 66.0%.
In May 2012, The U.S. Department of Health and Human Services released the National Plan to Address Alzheimer’s Disease (4), which includes a call to strengthen data and surveillance efforts. CDC’s Healthy Brain Initiative is working with the Alzheimer’s Association and numerous other national, state, and local partners to develop a set of public health actions to promote cognitive health as a vital, integral, component of public health and also to address issues related to cognitive impairment for persons living in the community and their care partners (i.e., informal and paid caregivers and health-care providers). This report provides a baseline estimate of the extent of self-reported increased confusion or memory loss and functional difficulties occurring in the preceding year among noninstitutionalized persons aged ≥60 years who might require services and supports now or in the future. The findings underscore the need to facilitate timely discussions with health-care and service providers so that linkages can be made to accurate information and needed services.
Current Tobacco Use and Secondhand Smoke Exposure Among Women of Reproductive Age — 14 Countries, 2008–2010
November 2, 2012 / 61(43);877-882
“……To examine current tobacco use and SHS (Secondhand Smoke ) exposure in women aged 15–49 years, data were analyzed from the 2008–2010 Global Adult Tobacco Survey (GATS) from 14 low- and middle-income countries: Bangladesh, Brazil, China, Egypt, India, Mexico, Philippines, Poland, Russia, Thailand, Turkey, Ukraine, Uruguay, and Vietnam. The results of this analysis indicated that, among reproductive-aged women, current tobacco smoking ranged from 0.4% in Egypt to 30.8% in Russia, current smokeless tobacco use was <1% in most countries, but common in Bangladesh (20.1%) and India (14.9%), and SHS exposure at home was common in all countries, ranging from 17.8% in Mexico to 72.3% in Vietnam. …..Prevalence of current smoking was ≤2.3% in Bangladesh, China, Egypt, India, Thailand, and Vietnam and >10% in Brazil, Poland, Russia, Turkey, Ukraine, and Uruguay. ……..”
Influenza Vaccination Coverage Among Pregnant Women — 2011–12 Influenza Season, United States
September 28, 2012 / 61(38);758-763
What is already known on this topic? Pregnant women are at increased risk for influenza-associated complications and are recommended to receive inactivated influenza vaccination regardless of trimester. Vaccination coverage among pregnant women was estimated at 32% (National 2009 H1N1 Flu Survey) and 47% (Pregnancy Risk Assessment Monitoring System) for the 2009–10 season and 38% (Behavioral Risk Factor Surveillance System) and 49% (Internet panel survey) for the 2010–11 influenza season.
What is added by this report? Approximately 47% of pregnant women in the Internet panel survey reported being vaccinated for influenza for the 2011–12 influenza season; 9.9% were vaccinated before pregnancy; 36.5% during pregnancy; and <1.0% after pregnancy. Women who received both health-care provider recommendations and offers to vaccinate had substantially higher vaccination coverage (73.6%) compared with other women (47.9% for those with recommendations but no offers, and 11.1% for those with neither).
What are the implications for public health practice? Continued efforts are needed to encourage health-care providers to educate their patients about the safety and effectiveness of vaccination and continually recommend and offer influenza vaccination to their pregnant patients. To overcome their concerns and fears, messages to pregnant women should emphasize the safety and effectiveness of maternal influenza vaccination for both the mother and baby.
Pregnant women and their newborns are at elevated risk for influenza-associated hospitalization and death (1). The Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG) have recommended influenza vaccination for all women who are or will be pregnant during the influenza season, regardless of trimester (1,2). To estimate influenza vaccination coverage among pregnant women for the 2011–12 influenza season, CDC analyzed data from an Internet panel survey (3) conducted April 3–17, 2012, among women pregnant at any time during the 4-month period October 2011–January 2012. Among 1,660 survey respondents, 47.0% reported they had received influenza vaccination; 9.9% were vaccinated before pregnancy, 36.5% during pregnancy, and <1.0% after pregnancy. Overall, 43.7% of women reported receipt of both a health-care provider recommendation and offer of influenza vaccination; these women had higher vaccination coverage (73.6%) than women who received only a recommendation but no offer of vaccination (47.9%) and women who received neither a recommendation nor an offer (11.1%). Continued efforts are needed to encourage providers of medical care to routinely recommend and offer influenza vaccination to women who are pregnant or who might become pregnant.
To provide timely end-of-season estimates of influenza vaccination coverage and information on knowledge, attitudes, and behaviors related to influenza vaccination among women pregnant during the 2011–12 influenza season, CDC conducted an Internet panel survey during April 3–17, 2012 that was similar to a survey conducted in April 2011 (3). Women aged 18–49 years who were pregnant at any time since August 2011 were recruited from a SurveySpot panel operated by Survey Sampling International.* Of 7,485 women who visited the Internet survey site during the study period, 2,223 were determined to be eligible for the survey based on the timing of their pregnancies; of those, 2,096 (94%) completed the online survey. Data were weighted to reflect the age group, racial/ethnic, and geographic distribution of the total U.S. population of pregnant women during 1995–2005.† The same questions used to determine pregnancy status in the April 2011 survey (3) were used in this survey. In addition, women pregnant since August 2011 but no longer pregnant at the time of their response were asked to provide the start and end months of pregnancy. For this analysis, the study population was limited to 1,660 women reporting pregnancy any time during the usual peak influenza vaccination period of October 2011–January 2012.
Survey respondents were asked questions about their knowledge and attitudes regarding influenza and influenza vaccination; their vaccination status before, during, and after pregnancy; their physician’s practices regarding influenza vaccination, place of vaccination, and reasons for not receiving influenza vaccination. Weighted analyses were conducted. Because opt-in Internet panels are not random samples, statistical measures such as compilation of confidence intervals and tests of differences cannot be performed.§
Of the 1,660 women pregnant at any time during October 2011–January 2012, 47.0% reported influenza vaccination since August 1, 2011: 9.9% were vaccinated before pregnancy; 36.5% during pregnancy; and 0.6% after pregnancy (Table 1). By trimester of pregnancy, the percentages vaccinated were similar (10.1%, 12.6%, and 11.8% during the 1st, 2nd, and 3rd trimester, respectively). Women aged 18–24 years had lower vaccination coverage (42.3%) than women aged 25–49 years (49.4%). Non-Hispanic black women had lower vaccination coverage (39.8%) than Hispanic women (48.8%), non-Hispanic white women (47.9%), and other non-Hispanic women (53.7%). Vaccination coverage estimates varied by U.S. Census regions from 43.9% in the south to 49.7% in the northeast (Table 1). Women with education beyond a college degree had higher coverage (61.3%) than those with a college degree (49.4%) or less than a college degree (42.8%). Women with private or military medical insurance had higher vaccination coverage (50.2%) than those without medical insurance (36.9%) (Table 1).
Of women in the April 2012 survey, 39.8% reported having received influenza vaccination for the 2010–11 influenza season. Among these women, vaccination coverage for the 2011–12 season was 86.5%, compared with 20.7% for those who did not receive vaccination for the 2010–11 season (Table 1).
Among women who received a health-care provider recommendation to be vaccinated, 81.6% were offered vaccination during a provider visit. Among women who received both a health-care provider recommendation and offer for influenza vaccination, 73.6% received influenza vaccination, which was substantially higher than for women whose health-care provider recommended but did not offer vaccination (47.9%) and for women who did not receive either a provider recommendation or offer (11.1%) (Table 1).
Among the 87.7% of women participants who indicated that they had visited a provider since August 2011, 62.9% received a provider recommendation for influenza vaccination (Table 2).Within each of the categories, the subgroups with lower percentages reporting receipt of a provider recommendation were non-Hispanic black (54.1%), having no medical insurance (46.4%), underweight before pregnancy (55.0%), not vaccinated for the previous season (48.6%), and visited a provider because of pregnancy five times or fewer (52.3%) (Table 2). The subgroups with a higher percentage receiving a provider recommendation were women with more than a college degree (71.9%), women who were vaccinated for the previous season (83.7%), and those with more than 10 pregnancy-related provider visits (76.0%) (Table 2).
Most women who received influenza vaccination received it at their obstetrician’s or midwife’s office (41.4%), at a non-obstetrician health-care provider’s office (20.7%), or a hospital, clinic or health center (17.5%). Other locations for vaccination included pharmacy/drug or grocery store (8.0%); health department (4.1%); and workplace, school, or others (8.3%).
Among unvaccinated women who received a health-care provider recommendation and offer of vaccination, when the main reason for nonvaccination was asked, the top three most common answers were 1) concern that the vaccination would cause influenza (25.6%); 2) concern about the safety risk to the baby (13.1%); and 3) not believing the vaccination was effective (12.5%) (Table 3). Among women reporting no provider offer for influenza vaccination, the same three answers for not being vaccinated were most frequently cited (Table 3).
Deborah K. Walker, EdD, Sarah Ball, ScD, Sara Donahue, DrPH, David Izrael, MS, Abt Associates Inc., Cambridge Massachusetts. K.P. Srinath, PhD Abt SRBI, New York, New York. Helen Ding, MD, Gary L. Euler, DrPH, Walter W. Williams, MD, Stacie M. Greby, DVM, James A. Singleton, PhD, Peng-Jun Lu, MD, Erin D. Kennedy, DVM, Carolyn B. Bridges, MD, Immunization Service Div, Lisa A. Grohskopf, MD, Influenza Div, National Center for Immunization and Respiratory Diseases; Denise J. Jamieson, MD, Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC. Corresponding contributors: Gary L. Euler, email@example.com, 404-639-8742; Helen Ding, firstname.lastname@example.org, 404-639-8513.
In previous years, estimates of annual influenza vaccination levels among pregnant women were consistently lower than 30% through the 2007–08 season, according to data from the National Health Interview Survey (4) and Behavioral Risk Factor Surveillance System (BRFSS) (5). During the 2009–10 influenza A (H1N1) pdm09 season, estimates increased to 32% (National 2009 H1N1 Flu Survey) (6) and 47% (Pregnancy Risk Assessment Monitoring System) (5). During the 2010–11 influenza season, estimates were 38%, according to BRFSS data (5) and 49%, based on the previous Internet panel survey (3). The findings in this report indicate that the level of influenza vaccination among pregnant women achieved during the two preceding seasons (3) was sustained during the 2011–12 season.
Women who received a health-care provider recommendation for influenza vaccination continued to be more likely to be vaccinated (5,6); in addition, women who received both a provider recommendation and an offer for influenza vaccination were more likely to be vaccinated than women who only received a provider recommendation. In this study, 81.6% of women with a recommendation to be vaccinated were offered vaccination during a visit with their provider. Among women in this group, vaccination coverage was 73.6%, nearly reaching the Healthy People 2020 target of 80% for pregnant women, regardless of provider recommendations or offers.¶
Studies of health-care providers have suggested that they are more likely to discuss influenza vaccination with their patients when they understand the vaccination guidelines for pregnant women, are vaccinated themselves, or provide vaccination at their practice (7–8). However, providers also might be more likely to recommend influenza vaccination to women who appear to be in favor of influenza vaccination. A previous study found that providers’ who did not recommend vaccination were more likely influenced by patient preference than the providers’ continuing education (9).
Even among the 288 women in the sample with more than 10 pregnancy-related provider visits, about one fourth reported they did not receive a provider recommendation for influenza vaccination. Providers might have administrative and financial barriers to routine offering of influenza vaccination, such as working in a solo practice, concern about the up-front cost of ordering vaccines, high costs of storing and maintaining vaccine inventory, and other logistical challenges of vaccine administration (10). In this study, women without medical insurance of any type or with less frequent provider visits related to pregnancy were less likely to receive a provider recommendation. Health-care providers should use every opportunity to recommend and offer vaccination if appropriate, and women who are pregnant or who might become pregnant should ask about influenza vaccination at their provider visits, and if necessary, make a visit just for influenza vaccination.
Among unvaccinated women, 25.6% who received a provider offer and recommendation indicated that the main reason they chose not to receive an influenza vaccination was concern that the vaccination would give them influenza; another 13.1% said they were concerned about the safety risk to their baby. Tailored education messages on vaccination safety delivered through multiple means including social media and text messaging might help change negative attitudes and false beliefs about vaccination.
The findings in this report are subject to at least four limitations. First, the survey was self-administered and not validated by medical record review. Second, the results were weighted to the distribution of pregnant women in the U.S. population, but the study sample did not include women without Internet access. Therefore, it might not be a representative sample of pregnant women and findings might not be generalizable to all pregnant women in the United States. Third, estimates might be biased if the selection processes for entry into the Internet panel and a woman’s decision to participate in this particular survey were related to receipt of vaccination. Comparing estimates, the Internet panel survey estimates for women pregnant at any time during October–January was 9 percentage points higher than the BRFSS estimate for women who were pregnant at interview during December–February for the 2010–11 influenza season (5) and 4 percentage points higher for the 2011–12 season (CDC, unpublished data, 2012). Additional comparisons with BRFSS and other available data sources over multiple seasons are needed to determine whether the more timely Internet panel survey estimates, despite sampling differences, provide valid assessments of trends. Finally, the results from these surveys might be subject to multiple sources of error, including but not limited to sampling error, coverage error, and measurement error.
Health-care provider recommendation and offer of influenza vaccination were associated with higher vaccination levels among pregnant women. Efforts to enhance provider practices are needed. Messages to pregnant women from providers should more strongly emphasize the safety and effectiveness of maternal influenza vaccination and the risk from influenza to mother and infants without maternal vaccination. Increasing knowledge among pregnant women regarding influenza risks and influenza vaccination safety might also increase opportunities for provider recommendations and offers to vaccinate.
John Boyle, PhD, Rachel Martonik, and Faith Lewis, Abt SRBI, Silver Spring, Maryland.
- CDC. Prevention and control of influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2010. MMWR 2010;59(No. RR-8).
- American Congress of Obstetricians and Gynocologists Committee on Obstetric Practice. ACOG committee opinion no. 468: influenza vaccination during pregnancy. Obstet Gynecol 2010;116:1006–7.
- CDC. Influenza vaccination coverage among pregnant women—United States, 2010–11 influenza season. MMWR 2012;60:1078–82.
- Lu P, Bridges CB, Euler GL, Singleton JA. Influenza vaccination of recommended adult populations, U.S., 1989–2005. Vaccine 2008;26:1786–93.
- Kennedy ED, Ahluwalia IB, Ding H, Lu PJ, Singleton JA, Bridges CB. Monitoring seasonal influenza vaccination coverage among pregnant women in the United States. Am J Obstet Gynecol 2012;207(3 Suppl):S9–16.
- Ding H, Santibanez TA, Jamieson DJ, et al. Influenza vaccination coverage among pregnant women—National 2009 H1N1 Flu Survey (NHFS). Am J Obstet Gynecol 2011;204(6 Suppl 1):S96–106.
- Silverman NS, Greif A. Influenza vaccination during pregnancy. Patients’ and physicians’ attitudes. J Reprod Med 2001;46:989–94.
- Panda B, Stiller R, Panda A. Influenza vaccination during pregnancy and factors for lacking compliance with current CDC guidelines. J Matern Fetal Neonatal Med 2011;24:402–6.
- McNeil S, Halperin B, MacDonald N. Influenza in pregnancy: the case for prevention. Adv Exp Med Biol 2009;634:161–83.
- Kissin DM, Power ML, Kahn EB, et al. Attitudes and practices of obstetrician-gynecologists regarding influenza vaccination in pregnancy. Obstet Gynecol 2011;118:1074–80.