Inuenza and Tetanus, Diphtheria, and Acellular Pertussis Vaccination During Pregnancy, Pregnancy Risk Assessment Monitoring System, 2019

Background Inuenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines is recommended for We analyzed 2019 data from the Pregnancy Risk Assessment Monitoring System, from 43 jurisdictions. We estimated the overall prevalence of women reporting receipt of a healthcare provider offer or recommendation for inuenza vaccine (n=44,528), and inuenza vaccine during the 12 months before delivery (n=44,213). We also estimated Tdap vaccine receipt during pregnancy from the 21 jurisdictions (n=22,972). Maternal inuenza and Tdap vaccination were examined by selected maternal characteristics and by jurisdiction.


Abstract Background
In uenza and tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines is recommended for pregnant women to protect themselves and their infants from adverse health outcomes.

Objectives
To estimate the prevalence of maternal in uenza and Tdap vaccination and determine factors associated with receipt of these vaccines.

Methods
We analyzed 2019 data from the Pregnancy Risk Assessment Monitoring System, from 43 jurisdictions. We estimated the overall prevalence of women reporting receipt of a healthcare provider offer or recommendation for in uenza vaccine (n=44,528), and in uenza vaccine during the 12 months before delivery (n=44,213). We also estimated Tdap vaccine receipt during pregnancy from the 21 jurisdictions (n=22,972). Maternal in uenza and Tdap vaccination were examined by selected maternal characteristics and by jurisdiction.

Results
Overall, 86.4% of women reported being offered or recommended an in uenza vaccination, and 60.8% of women reported receiving an in uenza vaccination in the 12 months prior to their delivery, ranging from 36.0% in Puerto Rico to 82.1% in Rhode Island. Tdap receipt during pregnancy was 73.7%, ranging from 52.2% in Mississippi to 85.1% in Vermont.
Prevalence of in uenza vaccination was lower among women aged 18-24 years (52.2%), who are non-Hispanic black (44.5%), with a high school diploma or less education (51.3%), with no prenatal insurance (43.2%), having no (42.0%) prenatal care, with ≥3 previous live births (49.3%) and not offered or recommended the in uenza vaccine by a healthcare provider (20.0%). Tdap vaccination also varied by all characteristics examined and was lower among similar groups of women observed to have lower in uenza vaccination uptake.

Conclusion
In 2019, in uenza and Tdap vaccination were suboptimal among women with a recent live birth. It is important that U.S. jurisdictions provide equitable access to these vaccines during pregnancy. These results may also inform efforts for vaccination for other infectious diseases among pregnant women.

Synopsis
A. Study question? To estimate prevalence of in uenza and Tetanus, Diphtheria, and Acellular Pertussis (Tdap) vaccination and determine factors associated with receipt of these vaccines among women who delivered a live birth in 2019.
B. What is already known? In uenza and Tdap vaccines protect pregnant women and their infants from adverse health outcomes. However, available national data show that receipt of these vaccines is suboptimal.
C. What does this study add to what is already known? Many women did not receive in uenza and Tdap vaccines and it varied widely by state of residence. Population-based prevalence estimates of maternal vaccination at the state level are crucial for tailoring vaccination campaigns and programs to maximize impact and to provide equitable access to in uenza and Tdap vaccines during pregnancy.

Background
In uenza during pregnancy is associated with severe maternal illness 1, 2 and increased risk of poor infant outcomes including preterm birth. 2 The Advisory Committee on Immunization Practices (ACIP) and the American College of Obstetricians and Gynecologists (ACOG) recommend that pregnant women receive in uenza vaccine to protect themselves and their infants. 3,4 ACIP speci cally recommends that all women who are pregnant or who might be pregnant or postpartum during the in uenza season receive in uenza vaccine. In uenza vaccine can be safely administered before and at any time during pregnancy, and has been shown to reduce the risk of infection by 50%, 5 the risk of hospitalization by an average of 40%, 6 and to protect infants from in uenza during the rst 6-months of life when infants are not eligible for in uenza vaccination. 7 Similarly, both ACIP and ACOG recommend the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine during every pregnancy, preferably in the early part of 27-36 weeks gestation. 8, 9 Tdap vaccination during pregnancy protects infants, during the rst 2-months of life, who are at the greatest risk of contracting pertussis and having severe complications from the infection including pneumonia and death. 10,11 Despite recommendations, available data show that prevalence of maternal vaccination is suboptimal, with variation by certain characteristics and receipt of healthcare providers recommendation or offer of a vaccine. 12 The Centers for Disease

Data Source and Population
PRAMS is an ongoing surveillance system conducted by CDC in collaboration with participating jurisdictions' health departments. Details about the PRAMS methodology have been published previously. 13 It uses a standardized mixed-mode mail and telephone questionnaire to obtain information from a population-based sample of women with recent live births; responses are linked to selected data extracted from the birth certi cate. The PRAMS questionnaire captures information about maternal behaviors and experiences before, during, and shortly after pregnancy. Each jurisdiction's questionnaire contains "core" questions. Jurisdictions also have the option to include "standard" questions which address additional topics of interest. Data are weighted for sample design, nonresponse, and noncoverage to produce estimates representative of participating jurisdictions' live birth populations. This analysis includes 43 jurisdictions (40 states, the District of Columbia, New York City, and Puerto Rico) that achieved a weighted response rate of ≥50%. The overall mean weighted response rate for these sites was 59%, ranging from 50-81%.
The PRAMS protocol was reviewed and approved by CDC's IRB and each participating PRAMS jurisdiction's IRB.

Exposures
Maternal characteristics of interest included sociodemographic characteristics (i.e., maternal age, race/Hispanic-ethnicity, education, prenatal Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) participation, and jurisdiction), indicators of healthcare access and utilization (i.e., type of prenatal care insurance, number of prenatal care visits), and previous live birth. Factors of interest were selected a priori based on previous literature. 12 Most characteristics were obtained from data available in the PRAMS dataset from the birth certi cate; however, prenatal insurance status, and healthcare provider offer of or recommendation for in uenza vaccination were obtained from the PRAMS survey.

Outcomes
To determine past-year in uenza vaccination prevalence for women who gave birth in 2019 and whether in uenza vaccine was offered or recommended by a healthcare provider, we analyzed 2019 PRAMS data from the 43 jurisdictions. To measure healthcare provider offer of or recommendation for an in uenza vaccination, all women were asked the core question, "During the 12 months before the delivery of your new baby, did a doctor, nurse, or other healthcare worker offer you a u shot or tell you to get one?" The response options included "no" and "yes." To measure in uenza vaccination prevalence before or during pregnancy, all women were asked the core question, "During the 12 months before the delivery of your new baby, did you get a u shot?" The response options included "no," "yes, before my pregnancy," and "yes, during my pregnancy." In four jurisdictions (Montana, Rhode Island, Washington, and New York City), women who did not get an in uenza vaccination were also asked the standard question, "What were your reasons for not getting a u shot during the 12 months before the birth of your new baby". They were asked to select "no" or "yes" for each statement which included "my doctor didn't mention anything about a u shot," "I was worried about side effects of the u shot for me," "I was worried that the u shot might harm my baby," "I was not worried about getting sick with the u," "I do not think the u shot works," "I don't normally get a u shot," and "Other" with the option to write in a response.
To measure Tdap vaccination prevalence during pregnancy, all women from 21 jurisdictions (20 states and New York City) were asked the following standard question included on their PRAMS survey, "During your most recent pregnancy, did you get a Tdap shot or vaccination? A Tdap vaccination is a tetanus booster shot that also protects against pertussis (whooping cough)." The response options included "no," "yes," and "I don't know." The PRAMS survey did not assess healthcare provider offer or recommendation for Tdap.

Statistical Analysis
We calculated the weighted prevalence, with 95% con dence intervals (CIs), of a healthcare provider offer or recommendation for in uenza vaccination, overall in uenza vaccination prevalence and overall Tdap vaccination prevalence, by jurisdiction, and by selected maternal characteristics. In addition, we evaluated variation in the prevalence of in uenza vaccination by reported receipt of a healthcare provider offer of or recommendation for an in uenza vaccine, overall and by maternal characteristics in a strati ed analysis.
We used Chi-squared testing (statistical signi cance level set at p-value <0.05) and 95% CIs (i.e., nonoverlap of CIs) to

Provider Offer of or Recommendation for In uenza Vaccination
Among 44,528 women who answered the question on whether a healthcare provider offered or recommended an in uenza vaccination, 86.4% of women reported receiving a provider offer or recommendation, ranging from 67.7% in Puerto Rico to 95.0% in New Hampshire (Figure 1). Receipt of provider offer or recommendation was lower among women aged ≤17 (72.7%) and 18-24 years (81.9%) compared with women aged 25-34 (87.9%) and ≥35 years (87.8%); non-Hispanic Black (82.7%) and Hispanic (81.9%) women compared with non-Hispanic White (89.0%), non-Hispanic American Indian or Alaska Native (89.3%), and non-Hispanic Asian or Paci c Islander (87.3%) women; women with no prenatal insurance (62.8%) and those with Medicaid (82.8%) compared with women with private prenatal insurance (90.7%); women with no prenatal care visits (73.1%), 1-5 visits (78.4%) compared with women with or 6-10 visits (84.5%) compared or ≥11 visits (88.5%), and women with no (84.9%) or ≥3 previous live births (83.7%) compared with women with one (88.6%) or two previous live births (88.1%); (Table 1). Healthcare provider offer or recommendation for an in uenza vaccine was lowest among women with a high school diploma or less education (81.5%) and prenatal WIC participants (82.9%).

In uenza Vaccination
Among 44,213 women who answered the question on in uenza vaccination, 60.8% reported being vaccinated (Table 2) in the year before their most recent live birth; 11.3% reported being vaccinated before pregnancy and 49.5% during pregnancy.
Past-year in uenza vaccination prevalence ranged from 36.0% in Puerto Rico to 82.1% in Rhode Island (Figure 1). Variation in in uenza vaccination by maternal characteristics followed similar patterns as prevalence of provider offer of or recommendation for in uenza vaccination ( Table 2). Prevalence of in uenza vaccination was lower among women aged women aged ≤17 (62.2%) and 18-24 years (69.6%) compared with women aged 25-34 years (75.5%), those who were non-Hispanic Black (63.2%) compared with non-Hispanic White (76.6%), Hispanic (73.0%), non-Hispanic Asian or Paci c Islander (72.6%) and non-Hispanic other (72.3%); women with no prenatal insurance (40.2%) and those with Medicaid (66.1%) compared with women with private prenatal insurance (80.7%); and those with zero (54.9%) or 1-5 prenatal care visits (55.5%) compared with 6-10 (70.4%) or ≥11 prenatal care visits (77.1%). Overall prevalence of Tdap vaccination was lowest among women who had ≤high school diploma (64.7%), prenatal WIC participants (67.7%), and had ≥3 previous live births (57.5%) ( Table 3) Examples of strategies several jurisdictions have implemented to address barriers to maternal vaccination include providing incentives to health plans, increasing access to vaccinations through alternative sites like pharmacies, and using data to identify populations and regions with substandard in uenza vaccination rates. 15 For example, compared with other jurisdictions, we found Massachusetts and Rhode Island were among the sites with the highest reported prevalence of in uenza vaccination being offered or recommended by a healthcare provider and past-year in uenza vaccination prevalence among women with a recent live birth. The Massachusetts Department of Health has a history of supporting vaccine education and access to vaccinations statewide through collaboration with community-based organizations to share tailored, accurate, and culturally appropriate messages about the importance of in uenza vaccination as well as establishing additional venues, including obstetrics sites, to administer the vaccine. 16 Massachusetts also has programs to reimburse public providers for administration of the vaccine to incentivize providers to incorporate vaccine programs in their practices. During the H1N1 pandemic, the Rhode Island Department of Health ensured that the in uenza vaccine was accessible to pregnant women statewide by recruiting obstetric providers; this led to dramatic increases in in uenza vaccination among pregnant women. 17 Rhode Island's Immunize for Life initiative offers pregnant women home visitation that includes vaccine education and referral. 18 Similar to other studies, 12,19 our ndings indicate that in uenza and Tdap vaccination prevalence was lower for women who were younger, non-Hispanic black, with a lower level of education, uninsured, had Medicaid insurance coverage for prenatal care, had less frequent prenatal care visits, participated in WIC during the prenatal period, and had higher number of previous live births. Also consistent with prior literature, 20,21 reasons cited for not getting an in uenza vaccination among pregnant women included that they don't normally get vaccinated, concerns about vaccine safety and effectiveness, not being worried about getting sick with in uenza, and lack of provider offer or recommendation. To improve maternal immunization, the development or continued support of organized, multidisciplinary efforts are needed to address vaccine hesitancy and ensure equitable access for all pregnant women regardless of sociodemographic characteristics and healthcare coverage. Vaccine hesitancy in African American communities is thought to stem from the mistrust that has developed due to a history of racial discrimination and exploitation in the United States which continue to the present day. 22 Efforts to prevent continued discrimination and exploitation as well as strategic messaging are needed to overcome this distrust in order to improve the con dence in getting any vaccine, including in uenza and Tdap vaccines.
In uenza vaccination prevalence was lower among women not offered or recommended in uenza vaccine by a healthcare provider. As observed previously with data from an Internet panel survey, receipt of a provider offer of vaccination is strongly associated with higher vaccination prevalence among pregnant women, for both in uenza and Tdap vaccines. 12 We observed differences in whether the in uenza vaccine was offered or recommended by a healthcare provider for all characteristics examined. This underscores the importance of equitable provision of care by healthcare providers discussing, offering, and/or recommending in uenza vaccination to all women who are pregnant or will be pregnant during in uenza season. However, among women who reported that a healthcare provider offered or recommended in uenza vaccine, vaccination prevalence still varied by sociodemographic characteristics, health insurance coverage, and receipt of prenatal care, highlighting the importance of addressing other factors in uencing in uenza vaccination beyond healthcare provider counseling.

Strengths of the study and limitations of the data
Strengths of this analysis include the use of a population-based sample of women with a recent live birth and the ability to estimate jurisdiction-level in uenza and Tdap vaccination prevalence. However, our ndings should be interpreted in the context of several limitations. PRAMS is a cross-sectional survey with self-reported data and subject to social desirability and recall bias. Women who receive a vaccine might be more likely to recall a conversation in which their provider offered or suggested that they get the vaccine. Additionally, the results for in uenza and Tdap vaccination may only be generalizable to women whose pregnancies ended in a live birth residing in the participating jurisdictions included in the analysis. Given that the survey does not report timing of healthcare provider offer of or recommendation for in uenza vaccine, we were unable to determine whether it happened prior to vaccination. Furthermore, the survey did not distinguish between an offer of or recommendation for in uenza vaccine, and women were not asked whether a healthcare provider offered or recommended Tdap vaccine. Also, we are unable to determine the prevalence of in uenza and Tdap vaccination by provider practice type. Last, we were unable to determine in uenza vaccination prevalence by speci c in uenza season because the survey asks about in uenza vaccination during the 12 months before delivery and does not capture the date the vaccine was received. However, all women delivering in 2019 would have been pregnant in either the 2018-2019 or 2019-2020 in uenza seasons.

Conclusion
In uenza and Tdap vaccination was suboptimal among women with a recent live birth in 2019. Vaccination prevalence varied by jurisdiction as well as by several factors, including receipt of a healthcare provider offer or recommendation for in uenza vaccination, sociodemographic characteristics, health insurance coverage, and receipt of prenatal care. Due to the recent decline in routine vaccination rates during the current COVID-19 pandemic, 23,24 it is more important than ever for jurisdictions to implement innovative approaches to improve vaccination rates, and to provide accurate and clear messages to address vaccine hesitancy. It is imperative that U.S. jurisdictions support strategies to provide equitable access to in uenza and Tdap vaccines during pregnancy including vaccination efforts against other infectious diseases that disproportionately impact pregnant women.

Declarations
Funding: Not applicable