Influenza Vaccination Coverage Among Pregnant Women — 2011–12 Influenza Season, United States

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).

Reported by

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 protected], 404-639-8742; Helen Ding, [email protected], 404-639-8513.

Editorial Note

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.

Acknowledgments

John Boyle, PhD, Rachel Martonik, and Faith Lewis, Abt SRBI, Silver Spring, Maryland.

References

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