Influenza and Tdap Vaccination Coverage Among Pregnant Women — United States, April 2018

Katherine E. Kahn, MPH; Carla L. Black, PhD; Helen Ding, MD; Walter W. Williams, MD; Peng-Jun Lu, MD, PhD; Amy Parker Fiebelkorn, MSN, MPH; Fiona Havers, MD; Denise V. D'Angelo, MPH; Sarah Ball, ScD; Rebecca V. Fink, MPH; Rebecca Devlin, MA

Disclosures

Morbidity and Mortality Weekly Report. 2018;67(38):1055-1059. 

In This Article

Abstract and Introduction

Introduction

Vaccinating pregnant women with influenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines can reduce the risk for influenza and pertussis for themselves and their infants. The Advisory Committee on Immunization Practices (ACIP) recommends that all women who are or might be pregnant during the influenza season receive influenza vaccine, which can be administered any time during pregnancy.[1] The ACIP also recommends that women receive Tdap during each pregnancy, preferably from 27 through 36 weeks' gestation.[2] To assess influenza and Tdap vaccination coverage among women pregnant during the 2017–18 influenza season, CDC analyzed data from an Internet panel survey conducted during March 28–April 10, 2018. Among 1,771 survey respondents pregnant during the peak influenza vaccination period (October 2017–January 2018), 49.1% reported receiving influenza vaccine before or during their pregnancy. Among 700 respondents who had a live birth, 54.4% reported receiving Tdap during their pregnancy. Women who reported receiving a provider offer of vaccination had higher vaccination coverage than did women who received a recommendation but no offer and women who did not receive a recommendation. Reasons for nonvaccination included concern about effectiveness of the influenza vaccine and lack of knowledge regarding the need for Tdap vaccination during every pregnancy. Provider offers or referrals for vaccination in combination with patient education could reduce missed opportunities for vaccination and increase vaccination coverage among pregnant women.

An Internet panel* survey was conducted to assess end-of-season influenza vaccination coverage and Tdap coverage estimates among women pregnant during the 2017–18 influenza season, as previously described.[3,4] The survey was conducted during March 28–April 10, 2018, among women aged 18–49 years who reported being pregnant at any time since August 1, 2017, through the date of the survey. Among 14,858 women who entered the survey site, 2,342 reported they were eligible, and of these, 2,236 completed the survey (cooperation rate = 95.5%). Data were weighted to reflect the age, race/ethnicity, and geographic distribution of the total U.S. population of pregnant women. Analysis of influenza vaccination coverage was limited to 1,771 women who reported being pregnant any time during the peak influenza vaccination period (October 2017–January 2018). A woman was considered to have been vaccinated against influenza if she reported receiving a dose of influenza vaccine (before or during her most recent pregnancy) since July 1, 2017. To accommodate the optimal timing for Tdap vaccination during 27 through 36 weeks' gestation, analysis of Tdap coverage was limited to women who reported being pregnant any time since August 1, 2017, and who had a live birth. A woman was considered to have received Tdap if she reported receiving a dose of Tdap vaccine during her most recent pregnancy. Among 815 women who had a live birth, 115 (14.1%) were excluded from analysis because they did not know if they had ever received Tdap vaccination (11.4%) or did not know if the Tdap vaccine was received during their pregnancy (2.7%), leaving a final analytic sample of 700. An estimate of the proportion of pregnant women who received both recommended maternal vaccines was assessed among these 700 women. A difference was noted as an increase or decrease when there was a ≥5 percentage-point difference between any values being compared.§

Among pregnant women, 49.1% reported receiving a dose of influenza vaccine since July 1, 2017 (Table); Tdap coverage during pregnancy was 54.4% among women with a recent live birth. Receipt of both influenza and Tdap vaccines (i.e., being fully vaccinated) was reported by 32.8% of women with a recent live birth (Figure 1). Influenza vaccination coverage increased with increasing number of provider visits since July 1, 2017, ranging from 18.1% (0 visits) to 56.8% (>10 visits) (Table).

Figure 1.

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) and influenza vaccination coverage* among women with a recent live birth — Internet panel survey, United States, April 2018
*Weighted percentage of women who reported 1) receiving influenza vaccine before or during pregnancy since July 1, 2017, and receiving Tdap vaccine during most recent pregnancy; 2) receiving influenza vaccine before or during pregnancy since July 1, 2017, but not receiving Tdap vaccine during most recent pregnancy; 3) receiving Tdap vaccine during most recent pregnancy but not receiving influenza vaccine before or during pregnancy since July 1, 2017; or 4) not receiving influenza vaccine before or during pregnancy since July 1, 2017, and not receiving Tdap vaccine during most recent pregnancy.

Among women pregnant any time during October 2017–January 2018, 66.6% reported receiving a provider offer of influenza vaccination, 14.5% received a recommendation but no offer, and 19.0% received no recommendation (Table). The percentages of women in these groups who received influenza vaccine were 63.8%, 37.6%, and 9.0%, respectively. Among women who reported that their provider recommended but did not offer influenza vaccination, 42.1% received a referral to get vaccinated elsewhere. Women with a referral were more likely to receive an influenza vaccination (47.9%) than were women who received a provider recommendation but did not receive a referral (30.1%).

Among women with a live birth since August 1, 2017, 67.4% reported receiving a provider offer of Tdap, 11.9% received a recommendation but no offer, and 20.7% received no recommendation (Table). The percentages of these women who received Tdap among these groups were 73.5%, 38.3%, and 1.6%, respectively. Among women who reported that their provider recommended but did not offer Tdap, 52.9% received a referral. Among women who received a referral, 56.1% received Tdap, compared with 18.5% of women who received a provider recommendation but did not receive a referral.

The most commonly reported main reason for not receiving influenza vaccination before or during pregnancy was belief that the vaccine is not effective (20.2%) (Figure 2). The most common main reason for not receiving Tdap during pregnancy was a lack of knowledge about the need to be vaccinated during every pregnancy (45.1%): 31.6% of women who did not receive vaccine during pregnancy reported having been vaccinated previously, and 13.5% reported not knowing they were supposed to receive Tdap during their recent pregnancy. The second most commonly reported main reason for nonreceipt of both vaccines was concern about safety risks to the baby (16.0% and 13.5% of women who did not receive influenza vaccine or Tdap, respectively).

Figure 2.

Main reasons for not receiving influenza vaccine* or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) among pregnant women who did not receive influenza vaccine (n = 817) or Tdap (n = 297) — Internet panel survey, United States, April 2018
*Main reason for not receiving influenza vaccination among women pregnant any time during October–January in the 2017–18 influenza season who were not vaccinated as of early April 2018 (n = 817). Excluded women who were not vaccinated but did not provide information on the reason for not being vaccinated (n = 1).
Main reason for not receiving Tdap among women who were recently pregnant at the time of the survey (March 28–April 10, 2018), had a live birth, and were not vaccinated during their most recent pregnancy (n = 297). Excluded women who were not vaccinated but did not provide information on the reason for not being vaccinated (n = 7).

*https://www.surveysampling.com.
An opt-in Internet panel survey is a nonprobability sampling survey. The denominator for a response rate calculation cannot be determined because no sampling frame with a selection probability is involved at the recruitment stage. Instead, the survey cooperation rate is provided.
§Additional information on obstacles to inference in nonprobability samples is available at: https://www.aapor.org/AAPOR_Main/media/MainSiteFiles/NPS_TF_Report_Final_7_revised_FNL_6_22_13.pdf and https://www.aapor.org/getattachment/Education-Resources/For-Researchers/AAPOR_Guidance_Nonprob_Precision_042216.pdf.aspx. Although the estimates reported here have variance, there has been no attempt to quantify the size of the variance.
Referral is defined based on a "yes" response to the question "Did any doctor, nurse, or medical professional suggest that you go someplace else to get the <flu/Tdap> vaccination?"

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