Maternal Immunization in the U.S.: A Nationwide Retrospective Cohort Study

Pertussis Epidemiology in Children: The Role of Maternal Immunization

In the last twelve months, a significant global increase in pertussis cases has been observed, particularly among infants under three months of age. This age group is at the highest risk for severe disease, hospitalization, and death. Maternal immunization with the Tdap vaccine during pregnancy has been recommended to protect newborns by transferring maternal antibodies transplacentally. This review examines the current epidemiology of pertussis, the importance of preventing it in young children, and the effectiveness of maternal immunization. Despite the proven benefits of maternal vaccination, which has been found effective in pertussis prevention in up to 90% of cases, coverage remains suboptimal in many countries. Factors contributing to low vaccination rates include vaccine hesitancy due to low trust in health authority assessments, safety concerns, practical barriers to vaccine access, and the impact of the COVID-19 pandemic, which disrupted routine vaccination services. The recent increase in pertussis cases may also be influenced by the natural cyclic nature of the disease, increased Bordetella pertussis (Bp) activity in older children and adults, and the genetic divergence of circulating Bp strains from vaccine antigens. Given the high efficacy of maternal vaccination in preventing pertussis in infants, increasing coverage rates is crucial. Efforts to improve vaccine uptake should address barriers to access and vaccine hesitancy, ensuring consistent immune protection for the youngest and most vulnerable populations. Enhanced maternal vaccination could significantly reduce the incidence of whooping cough in infants, decreasing related hospitalizations and deaths.

Routine Maternal Vaccine Uptake during the COVID-19 Pandemic

OBJECTIVE

This study examines the impact of the coronavirus disease 2019 (COVID-19) pandemic on influenza and tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine uptake in a pregnant, low-income population.

STUDY DESIGN

This retrospective cohort study included women initiating prenatal care before (May-November 2019) or during the COVID-19 pandemic (May-November 2020) at two large Medicaid clinics. All patients entered prenatal care before 20 weeks and delivered full-term. Medical records were reviewed for vaccine uptake and demographic data. Multivariate logistic regression analysis was used to compare vaccination rates prior to and during the COVID-19 pandemic. Additional analysis was performed to identify association of demographic factors with vaccine uptake. IRB approval was obtained for this study.

RESULTS

A total of 939 patients met inclusion criteria, with 462 initiating care prior to and 477 initiating care during the COVID-19 pandemic. Influenza vaccination uptake was 78% (362/462) in the prepandemic group, significantly decreasing to 61% (291/477) in the pandemic group (p <0.01, odds ratio [OR] = 0.38, confidence interval [CI]: 0.26-0.53). Tdap vaccination uptake was 85% (392/462) in the prepandemic group, significantly decreasing to 76% (361/477) in the pandemic group (p <0.01, OR = 0.56, CI: 0.40-0.79). The decrease in influenza vaccine uptake was most significant in non-Hispanic Black patients, decreasing from 64% (73/114) in the prepandemic group to 35% (35/101) in the pandemic group (p <0.01, OR = 0.30, CI: 0.17-0.52), while there was no significant difference in age or parity in relation to vaccination status.

CONCLUSION

Routine vaccination uptake significantly decreased during the COVID-19 pandemic in a low-income population of pregnant women, with decrease more pronounced on influenza vaccine than on Tdap vaccine uptake, especially in non-Hispanic Black patients.

KEY POINTS

· Influenza and Tdap vaccination uptake during pregnancy has decreased during the COVID-19 pandemic.. · Influenza vaccine uptake decreased more than Tdap in pregnancy during the COVID-19 pandemic.. · The greatest decrease was seen in influenza vaccine uptake in non-Hispanic Black patients..

Influenza vaccination in pregnant women in Iceland 2010-2020 and the burden of influenza in pregnant women and their infants

INTRODUCTION

Influenza vaccinations are recommended in pregnancy to protect both the pregnant woman and the unborn baby. The aim of this study was to assess the influenza vaccine uptake among pregnant women in Iceland in ten influenza seasons and to estimate the influenza disease burden on pregnant women and their infants.

METHODS

This was a retrospective, descriptive study on influenza vaccine uptake among pregnant women and the burden of influenza and influenza-like illness (ILI) among pregnant women and their infants in ten influenza seasons. All women attending a 20-week ultrasound at Landspitali University Hospital in Reykjavik in August-April each influenza season 2010-2020 were included in the study. Data on influenza vaccinations and influenza/ILI diagnoses was collected from central national databases.

RESULTS

The influenza vaccine uptake increased from 6.2 % in 2011-2012 to 37.5 % in 2019-2020. The incidence rate of influenza/ILI among pregnant women ranged from 5.5 to 22.1/1000 person-years. The estimated vaccine effectiveness in the ten influenza seasons was 34-100 %. The incidence rate of influenza/ILI among infants < 12 months of age was 0-13.4/1000 person-years. Influenza vaccinations in pregnancy are protective against influenza/ILI in pregnant women (IRR 0.36, 95 % CI 0.22-0.58), infants in the season of vaccination (IRR 0.40, 95 % CI 0.17-0.97) and probably for infants < 6 months of age (IRR 0.51, 95 % CI 0.22-1.21).

CONCLUSIONS

Influenza vaccine coverage in pregnancy is suboptimal. Influenza vaccinations in pregnancy provide significant protection against influenza/ILI for pregnant women and infants in the season of vaccination. Initiatives to improve maternal vaccination coverage are needed.

The impact of maternal pertussis vaccination recommendation on infant pertussis incidence and mortality in the USA: an interrupted time series analysis

BACKGROUND

Pertussis is a contagious respiratory disease. Maternal tetanus-diphtheria-acellular pertussis vaccination during pregnancy has been recommended by the United States Centres for Disease Control (US CDC) Advisory Committee on Immunization Practices (ACIP) for unvaccinated pregnant women since October 2011 to prevent infection among infants; in 2012, ACIP extended this recommendation to every pregnancy, regardless of previous vaccination status. The population-level effect of these recommendations on infant pertussis is unknown. This study aimed to examine the impact of the 2011/2012 ACIP pertussis recommendation on pertussis incidence and mortality among US infants.

METHODS

We used monthly data on pertussis deaths among infants aged <1 year between January 2005 and December 2017 in the CDC Death Data and yearly infant pertussis incidence data from the CDC National Notifiable Disease Surveillance System to perform an interrupted time series analysis, accounting for the passage of the Affordable Care Act.

RESULTS

This study included 156 months of data. A potential decline in trend in infant pertussis incidence was noted during the post-recommendations period. No appreciable differences in trend were found in population-level infant pertussis mortality after the guideline changes in both adjusted and unadjusted models. Results were similar for all mortality sensitivity analyses.

CONCLUSIONS

The 2011/2012 ACIP maternal pertussis vaccination recommendations were not associated with a population-level change in the trend in mortality, but were potentially associated with a decrease in incidence in the USA between 2005 and 2017.

Maternal Tdap and influenza vaccination uptake 2017-2021 in the United States: Implications for maternal RSV vaccine uptake in the future

BACKGROUND

Assessment of maternal vaccine coverage is important for understanding and quantifying the impact of currently recommended vaccines as well as modeling the potential impact of future vaccines. However, existing data lack detail regarding uptake according to week of gestational age (wGA). Such granularity is valuable for more accurate estimation of vaccine impact.

OBJECTIVE

To summarize contemporary maternal Tdap vaccination uptake, overall, yearly, and by wGA, and maternal influenza vaccination uptake, overall, by influenza observation year, immunization month, and delivery month, in the US.

METHODS

Female patients 18-49 years of age with a pregnancy resulting in a live born infant (i.e., delivery) between 2017 and 2021 were selected from the Optum electronic health records (EHRs) database. Recently published gestational age algorithms were utilized to estimate wGA.

RESULTS

Of 1,021,260 deliveries among 886,660 women between 2017-2021, 55.1% had Tdap vaccination during pregnancy; vaccine coverage varied slightly by year (2017: 56.6%; 2018: 55.2%; 2019: 55.2%; 2020: 54.7%; 2021: 52.1%). Most (64.4%) maternal Tdap vaccinations occurred 27-32 wGA; 79.5% occurred during the entire 10-week recommended vaccination window (27-36 wGA). In the evaluation of influenza vaccination uptake (n=798,113 deliveries; 714,841 women), 33.5% of deliveries had influenza vaccination during influenza observation years 2017-2021, most (73.0%) of which occurred during influenza peak activity months (October-January) with approximately one-quarter (27.0%) of vaccinations having occurred during the off-peak months, mostly in September.

CONCLUSIONS

In this large contemporary analysis of EHR data, uptake of Tdap vaccination during pregnancy was consistent with previously published estimates; notably, most vaccination occurred early in the recommended 27-36 wGA window. Maternal influenza vaccination uptake largely correlated with peak influenza activity months and not gestational age. These study findings may have important implications for estimating the potential uptake and impact of future maternal vaccines.

Effectiveness of maternal immunisation with a three-component acellular pertussis vaccine at preventing pertussis in infants in the United States: Post-hoc analysis of a case-control study using Bayesian dynamic borrowing

BACKGROUND

Immunisation during pregnancy with a tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine can protect infants against pertussis between birth and paediatric vaccination. We aimed to estimate the vaccine effectiveness (VE) of third-trimester pregnancy immunisation with the three-component acellular pertussis (Td3ap) vaccine at preventing pertussis in infants <2 months in the United States (US), to support a label update.

METHODS

We performed a post-hoc sub-analysis of a case-control study conducted in six US Emerging Infections Program Network states between 2011 and 2014. Our analysis included only cases and controls whose mothers were either vaccinated with Td3ap or did not receive any Tdap vaccine. The association between Td3ap maternal immunisation and pertussis in infants was assessed for US data using a frequentist method with conditional logistic regression. A robustified analysis was conducted using Bayesian dynamic borrowing of non-US data, considering a mixing-weighted prior of 90% for historical non-US VE data, and of 10% for a vague prior. VE was estimated as (1-odds ratio) × 100%. Sensitivity analyses accounting for the impact of each non-US study, different mixing weights and missing/ambiguous data were performed.

RESULTS

We included 108 cases and 183 controls. Based on US data, the estimated VE of third-trimester maternal immunisation with Td3ap at preventing pertussis in infants <2 months was 78.0% (95% confidence interval: -38.0; 96.5). VE estimated by Bayesian dynamic borrowing of non-US data (with a 90% weight for historical data) was 83.4% (95% credible interval: 55.7; 92.5); sensitivity analyses produced similar VE estimates.

CONCLUSIONS

Effectiveness of third-trimester pregnancy immunisation with Td3ap at preventing infant pertussis in the US is very likely to be ≥ 50% and is most likely ∼ 80%. Bayesian dynamic borrowing of non-US VE data allowed overcoming the limited power (due to small sample size) of a brand-specific sub-analysis by considering additional evidence.

Maternal Vaccination and Vaccine Hesitancy

The American College of Obstetrics and Gynecology recommends influenza vaccine annually, Tdap with each pregnancy, and COVID-19 vaccine for those not previously vaccinated or who are due for boosters. The influenza and COVID-19 vaccines are safe during pregnancy and are effective in reducing morbidity in both the pregnant person and infant. The Tdap vaccine is given primarily to protect the newborn from pertussis through transplacental antibody transfer. Methods to enhance vaccination rates include stocking and giving vaccines in the obstetric office, recommending eligible vaccines at each visit, and focusing on the health of the infant in conversations with patients.

Tetanus, Diphtheria, and Acellular Pertussis Vaccination Coverage Among Publicly Insured Pregnant Women, U.S., 2016-2019

Introduction

Vaccination with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during pregnancy is highly effective against Bordetella pertussis in young infants. We aimed to evaluate the uptake of maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination during the recommended gestation period of 27 through 36 weeks among women enrolled in a public medical insurance plan in the U.S.

Methods

In this analysis using Centers for Medicare and Medicaid Services insurance claims data, we identified women aged 15 through 49 years who delivered a live-born infant from 2016 through 2019. We identified claims for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination to calculate the proportion of women who were vaccinated during Weeks 27 through 36 of gestation in each calendar year. We also assessed the average annual maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis coverage by age group, race and ethnicity, U.S. Census region of residence, and plan type. Data were analyzed in 2021.

Results

Among 4,318,823 deliveries, the 4-year national average for tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccination was 26%, improving from 22% in 2016 to 31% in 2019 (p<0.001). Within subgroups, the lowest 4-year average coverage was among women aged 15 through 18 years (22%); Black, non-Hispanic (23%) and Hispanic women (24%); those residing in the South (18%); those enrolled in a Children's Health Insurance Program plan (22%); and those covered by a fee-for-service plan (19%). Coverage increased across all subgroups from 2016 through 2019.

Conclusions

Although maternal tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis coverage among publicly insured women in the U.S. increased from 2016 through 2019, it remained considerably lower than estimated national coverage, with notable differences by race and ethnicity.

A Prospective Cohort Study on Pregnancy Outcomes of Persons Immunized with a Seasonal Quadrivalent Inactivated Influenza Vaccine during Pregnancy

This US-based, prospective observational cohort study evaluated the safety of a quadrivalent inactivated influenza vaccine (IIV4; Afluria Quadrivalent) in pregnant persons immunized over four influenza seasons between 2017 and 2021. Pregnancy outcomes included live birth, stillbirth, spontaneous abortion, and elective termination. Infant events of interest were major congenital malformations (MCMs), preterm birth (<37 weeks gestational age), and low birth weight (LBW). Data were descriptive; prevalence point estimates were reported with 95% confidence intervals (CI). A total of 483 pregnant persons were given IIV4 and evaluated; 477 (98.8%) reported a live birth, and there were 2 stillbirths, 4 spontaneous abortions, and no elective terminations or maternal deaths. The prevalence rates of infant events were as follows: preterm birth, 7.2% (upper 95% CI, 9.6%); LBW, 5.4% (upper 95% CI, 7.4%); and MCMs, 0.8% (upper 95% CI, 1.9%). Point estimates and upper 95% CIs of the observed prevalence rates were lower than or similar to background prevalence in the general US population. Our findings suggest no evidence of a safety concern with vaccinating this group at high risk of influenza complications and are consistent with published data from databases and surveillance systems that monitor the safety of influenza vaccines in pregnant persons.

Influenza vaccination during pregnancy and risk of selected major structural noncardiac birth defects, National Birth Defects Prevention Study 2006-2011

PURPOSE

To assess associations between influenza vaccination during etiologically-relevant windows and selected major structural non-cardiac birth defects.

STUDY DESIGN

We analyzed data from the National Birth Defects Prevention Study, a multisite, population-based case-control study, for 8233 case children diagnosed with a birth defect and 4937 control children without a birth defect with delivery dates during 2006-2011. For all analyses except for neural tube defects (NTDs), we classified mothers who reported influenza vaccination 1 month before through the third pregnancy month as exposed; the exposure window for NTDs was 1 month before through the first pregnancy month. For defects with five or more exposed case children, we used logistic regression to estimate propensity score-adjusted odds ratios (aORs) and 95% confidence intervals (CIs), adjusting for estimated delivery year and season; plurality; maternal age, race/ethnicity, smoking and alcohol use, low folate intake; and, for NTDs, folate antagonist medications.

RESULTS

There were 334 (4.1%) case and 197 (4.0%) control mothers who reported influenza vaccination from 1 month before through the third pregnancy month. Adjusted ORs ranged from 0.53 for omphalocele to 1.74 for duodenal atresia/stenosis. Most aORs (11 of 19) were ≤1 and all adjusted CIs included the null. The unadjusted CIs for two defects, hypospadias and craniosynostosis, excluded the null. These estimates were attenuated upon covariate adjustment (hypospadias aOR: 1.25 (95% CI 0.89, 1.76); craniosynostosis aOR: 1.23 (95% CI: 0.88, 1.74)).

CONCLUSIONS

Results for several non-cardiac major birth defects add to the existing evidence supporting the safety of inactivated influenza vaccination during pregnancy. Under-reporting of vaccination may have biased estimates downward.

Association of Maternal Tdap Recommendations With Pertussis Hospitalizations of Young Infants

BACKGROUND

It is well established that young infants have the highest risk of severe pertussis, which often results in hospitalization. Since the 2012 recommendation of administering tetanus toxoid, diphtheria toxoid, and acellular pertussis (Tdap) vaccine for every pregnancy, evaluation of pertussis hospitalizations among young infants in the United States has been limited.

METHODS

In this ecological study, we used the Kids' Inpatient Database, the largest all-payer pediatric inpatient database in the United States, to study pertussis hospitalizations among infants <1 month of age from 2000 to 2016.

RESULTS

The overall rate of pertussis hospitalizations before the Tdap vaccination recommendation was 5.06 per 100 000 infants (95% confidence interval, 4.36-5.76) and 2.15 per 100 000 infants (95% confidence interval, 1.49-2.81) afterward.

CONCLUSIONS

This study supports maternal vaccination against pertussis as an important strategy in protecting young infants, and continued evaluation is needed to assess the long-term trends in hospitalization.

Coverage for pertussis vaccination during pregnancy with 4 models of vaccine delivery: a quasiexperimental, multicentre observational study

BACKGROUND

Vaccination of pregnant people with a vaccine containing acellular pertussis (tetanus-diphtheria-acellular pertussis [Tdap]) has been recommended in Canada since 2018, and the evaluation of delivery models for efficient maternal Tdap administration is a priority for the Quebec Ministry of Health. We implemented 3 vaccine delivery models, in addition to the existing standard of practice model, and compared the vaccine coverage achieved by the 4 models in Quebec.

METHODS

In this quasiexperimental, multicentre observational study, we recruited pregnant people at less than 21 weeks' gestation in 4 Quebec regions from April to October 2019. We compared 4 vaccine delivery models: local community service centres (centre local de services communautaires [CLSCs], baseline), family medicine groups (FMGs), obstetrics clinic and the oral glucose challenge test (OGCT). In addition to the CLSCs, 3 FMGs, 1 obstetric clinic and a hospital-based OGCT screening program participated. We determined vaccination status from a self-reported questionnaire, the Quebec Immunization Registry or medical charts. We compared model-specific (for participants recruited to a model and subsequently vaccinated within that model) and overall vaccine coverage (considering all vaccine delivery pathways) and used logistic regression to adjust for sociodemographic variables.

RESULTS

Overall, 946 of 1000 recruited pregnant people were eligible for analyses. Vaccination via the FMGs achieved the highest model-specific vaccine coverage (67.8%, 95% confidence interval [CI] 60.5%-74.4%), but coverage was not significantly different from the CLSCs (63.8%, 95% CI 57.6%-69.6%). For overall vaccine coverage, the FMG (86.5%, 95% CI 80.6%-90.9%) and obstetrics models (85.9%, 95% CI 80.9%-89.7%) achieved significantly higher vaccine coverage than the CLSCs (66.3%, 95% CI 60.1%-71.9%). The OGCT model did not improve overall vaccine coverage (61.8%, 95% CI 56.1%-67.2%).

INTERPRETATION

Compared with CLSCs, overall vaccine coverage was higher when Tdap was offered in FMGs or an obstetrics clinic providing prenatal care. Health professionals involved in pregnancy follow-up recommending and offering the vaccine may be a key factor in optimizing vaccine coverage.

Vaccine exposure during pregnancy among privately and publicly insured women in the United States, 2016-2018

BACKGROUND

Vaccine use during pregnancy affects maternal and infant health. Many women do not receive vaccines recommended during pregnancy; conversely, inadvertent exposure to vaccines contraindicated or not recommended during pregnancy may occur. We assessed exposure to two recommended vaccines and two vaccines not recommended during pregnancy among privately and Medicaid-insured women in the United States.

METHODS

This study includes a retrospective cohort of pregnancies in women aged 12-55 years resulting in live birth, spontaneous abortion, or stillbirth identified in the IBM® MarketScan® Commercial, Blue Health Intelligence® (BHI®) Commercial, and IBM MarketScan Multi-State Medicaid Databases from August 1, 2016, to December 31, 2018. Gestational age at vaccination was determined using a validated algorithm. We examined vaccines (1) recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices (ACIP) (tetanus, diphtheria, and acellular pertussis [Tdap]; inactivated influenza) and (2) not recommended (human papillomavirus [HPV]) or contraindicated (measles, mumps, and rubella [MMR]).

RESULTS

We identified 496,771 (MarketScan Commercial), 858,961 (BHI), and 289,573 (MarketScan Medicaid) pregnancies (approximately 75% aged 20-34 years). Across these three databases, 52.1%, 50.3%, and 31.3% of pregnancies, respectively, received Tdap, most often at a gestational age of 28 weeks, and influenza vaccination occurred in 32.1%, 30.8%, and 18.0% of pregnancies, respectively. HPV vaccination occurred in < 0.2% of pregnancies, mostly in the first trimester among women aged 12-19 years, and MMR was administered in < 0.1% of pregnancies. Use of other contraindicated vaccines per ACIP (e.g., varicella, live attenuated influenza) was rare.

CONCLUSION

Maternal vaccination with ACIP-recommended vaccines was suboptimal among privately and Medicaid-insured patients, with lower vaccination coverage among Medicaid-insured pregnancies than their privately insured counterparts. Inadvertent exposure to contraindicated vaccines during pregnancy was rare. This study evaluated only vaccinations reimbursed among insured populations and may have limited generalizability to uninsured populations.

Using a Harm Reduction Model to Reduce Barriers to Vaccine Administration

Vaccination is a strategic public health measure designed to reduce the adverse effects of many infectious diseases. Although national recommendations exist for vaccine administration across the life span, immunization rates are affected by barriers to vaccine access and hesitancy in vaccine acceptance. Midwives and women's health clinicians are optimally poised to assess their client's vaccination status and provide vaccinations during clinical encounters. In order to address client concerns about vaccine safety and administration, each clinician is expected to be knowledgeable about vaccine benefits, recommendations, side effects, and potential adverse reactions. Socioeconomic factors, social policies, and historic and continued experiences related to racism have been identified as barriers to ready access to vaccinations and vaccine acceptance. Midwives can act as leaders within their practice sites and communities through participation in projects that reduce barriers to vaccine access and uptake. Community vaccine outreach programs and relationship-based care can increase vaccine uptake through improved health literacy and associated behavioral changes including greater vaccine acceptance. This article focuses on identifying barriers to vaccine uptake and describing harm reduction measures designed to improve uptake of vaccines. A variety of leadership activities are discussed that can improve clinicians' understanding of their role in optimizing vaccination.

Coverage and Timing of Influenza Vaccination Among Privately Insured Pregnant Women in the United States, 2010-2018

OBJECTIVE

Pregnant women are at increased risk of serious complications from influenza and are recommended to receive an influenza vaccination during pregnancy. The objective of this study was to assess trends, timing patterns, and associated factors of influenza vaccination among pregnant women.

METHODS

We used 2010-2018 MarketScan data on 1 286 749 pregnant women aged 15-49 who were privately insured to examine trends and timing patterns of influenza vaccination coverage. We examined descriptive statistics and identified factors associated with vaccination uptake by using multivariate log-binomial and Cox proportional hazard models.

RESULTS

In-plan influenza vaccination coverage before delivery increased from 22.0% during the 2010-2011 influenza season to 33.2% during the 2017-2018 influenza season. About two-thirds of vaccinated women received the vaccine in September or October during each influenza season. For women who delivered in September through May, influenza vaccination coverage increased rapidly at the beginning of influenza season and flattened after October. For women who delivered in June through August, influenza vaccination coverage increased gradually until February and flattened thereafter. Most vaccinated women who delivered before January received the vaccine in the third trimester. Increased likelihood of being vaccinated was associated with age 31-40, living in a metropolitan statistical area, living outside the South, enrollment in a consumer-driven or high-deductible health plan, being spouses or dependents of policy holders, and delivery in November through January.

CONCLUSIONS

Despite increases during the past several years, vaccination uptake is still suboptimal, particularly after October. Health care provider education on timing of vaccination and recommendations throughout influenza seasons are needed to improve influenza vaccination coverage among pregnant women.

Disparities in maternal influenza immunization among women in rural and urban areas of the United States

Pregnant women and their infants are at high risk of influenza-associated complications. Although maternal immunization offers optimal protection for both, immunization rates remain low in the U.S. Women in rural communities may represent a difficult to reach group, yet immunization rates among rural-residing women have not been well evaluated. We analyzed data from the 2016-2018 Phase-8 Pregnancy Risk Assessment Monitoring System for 19 U.S. states, including 45,018 women who recently gave birth to a live infant. We compared the prevalence of influenza vaccination prior to or during pregnancy and receipt of a vaccine recommendation from a healthcare provider for rural vs. urban-residing women. We used average marginal predictions derived from multivariate logistic regression models to generate weighted adjusted prevalence ratios (aPR) and corresponding 95% CIs. Of the 45,018 respondents, 6575 resided in a rural area; 55.1% (95% CI: 53.3, 56.9) of rural-residing women and 61.3% (95% CI: 60.6, 61.9) of urban-residing women received an influenza vaccine prior to or during pregnancy. The prevalence of vaccination was 4% lower among rural-residing women (aPR: 0.96; 95% CI: 0.93, 0.99). The greatest difference in rural vs. urban immunization rates were observed for Hispanic women and women with no health insurance. Our results indicate that pregnant women residing in rural communities have lower rates of immunization. To prevent maternal and infant health disparities, it is important to better understand the barriers to maternal immunization along with efforts to overcome them.

Insurance status predicts self-reported influenza vaccine coverage among pregnant women in the United States: A cross-sectional analysis of the National Health Interview Study Data from 2012 to 2018

While the influenza vaccine is recommended for all pregnant women, influenza vaccine coverage among this high-risk population remains inadequate. Factors associated with vaccine coverage among pregnant women, including insurance status, are poorly understood. In a cross-sectional study of the National Health Interview Survey (NHIS) data from 2012 to 2018, we evaluated predictors of self-reported influenza vaccine coverage in pregnant women. Among 1,942 pregnant women surveyed, 39% reported receiving the influenza vaccine in accordance with national recommendations. Influenza vaccine coverage increased by 8 percentage points from 2012 to 2018. Only 15% of uninsured pregnant women received the influenza vaccine, compared to 41% of those with insurance (design-corrected F-test, p-value < 0.001). In the multivariate Poisson regression analysis, significant predictors of influenza vaccine coverage were health insurance (prevalence ratio [PR] 1.90, 95% confidence interval [CI] 1.23-2.93), ratio of household income to federal poverty level (FPL) threshold greater than 400% (PR 1.54, 95% CI 1.20-1.96), graduate school education (PR 1.52, 95% CI 1.04-2.23), and the 2015-2018 survey year period (PR 1.27, 95% CI 1.08-1.49). While previous literature focuses heavily on demographics, our research underscores the need to further explore modifiable factors that impact vaccine uptake during pregnancy, particularly the interplay between health insurance and access to care.

Sociodemographic and health-related determinants of seasonal influenza vaccination in pregnancy: A systematic review and meta-analysis of the evidence since 2000

INTRODUCTION

Vaccination is considered to be the most practical and effective preventative measure against influenza. It is highly recommended for population subgroups most at risk of developing complications, including pregnant women. However, seasonal influenza vaccine uptake remains suboptimal among pregnant women, even in jurisdictions with universal vaccination. We summarized the evidence on the determinants of seasonal influenza vaccine uptake during pregnancy to better understand factors that influence vaccine uptake among pregnant women.

MATERIAL AND METHODS

We systematically searched MEDLINE, Embase and CINAHL from January 2000 to February 2020 for publications in English reporting on sociodemographic and/or health-related determinants of seasonal influenza vaccine uptake during pregnancy. Two reviewers independently included studies. One reviewer extracted data and assessed study quality, and another reviewer checked extracted data and study quality assessments for errors. Disagreements were resolved through consensus, or a third reviewer. We meta-analyzed using the inverse variance, random-effects method, and reported the odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

From 1663 retrieved citations, we included 36 studies. The following factors were associated with increased seasonal influenza vaccine uptake: Older age (20 studies: OR 1.13, 95% CI 1.07-1.20), being nulliparous (13 studies: OR 1.26, 95% CI 1.15-1.38), married (8 studies: OR 1.11, 95% CI 1.07-1.15), employed (4 studies: OR 1.13, 95% CI 1.02-1.24), a non-smoker (8 studies: OR 1.25, 95% CI 1.04-1.51) and having prenatal care (3 studies: OR 3.36, 95% CI 2.25-5.02), a chronic condition (6 studies: OR 1.30, 95% CI 1.17-1.44), been previously vaccinated (9 studies: OR 4.88, 95% CI 3.14-7.57) and living in a rural area (9 studies: OR 1.09, 95% CI 1.05-1.14). Compared with being black, being white was also associated with increased seasonal influenza vaccine uptake (11 studies: OR 1.30, 95% CI 1.20-1.41).

CONCLUSIONS

The evidence suggests that several sociodemographic and health-related factors may determine seasonal influenza vaccination in pregnancy, and that parity, history of influenza vaccination, prenatal care and comorbidity status may be influential.

Determinants of policy and uptake of national vaccine programs for pregnant women: results of mixed method study from Spain, Italy, and India

An important strategy for addressing maternal and newborn risks of disease is through vaccinating pregnant women. We conducted a mixed-methods study including a narrative literature review of drivers of maternal vaccination and key informant interviews in Spain, Italy, and India to characterize different approaches to national maternal immunization programs. Fifty-nine respondents participated in the study conducted between November 2018 and January 2019. Policies in Spain and Italy both reflect a life-course approach to vaccination, but recommendations and how they ensure uptake differs. Italy was focused on tracking of progress and mandates to ensure compliance in all regions, while Spain, an early adopter, relied more on advocacy and building provider acceptance. India includes Td in their national program, but the political will and advocacy for other vaccines are not seen. Needs for improving rates of maternal vaccination include education of health-care providers and pregnant women, use of central registries to track progress, stronger global guidance for use of vaccines, and engagement of champions, particularly obstetrician-gynecologists (ob-gyns). Health security concerns can also be leveraged to build political priority and needed platforms to detect disease and deliver vaccines in some countries. Understanding what drives a country’s maternal immunization program decisions and the success of implementation is useful in designing strategies to share best practices and guide support to strengthen platforms for maternal vaccination.

A Qualitative Study of Views and Experiences of Women and Health Care Professionals about Free Maternal Vaccinations Administered at Community Pharmacies

Background: A policy to extend funding of maternal pregnancy influenza and pertussis vaccinations to community pharmacies could address low pregnancy vaccine uptake. The policy has been implemented in one region in New Zealand. This study explored the views and experiences of women eligible for the vaccines and health care professionals regarding funded maternal vaccinations in pharmacy. Methods: Women in late pregnancy or with an infant, and midwives, pharmacists, and general practice staff were selected purposively and interviewed regarding maternal vaccinations and the new policy, including their awareness and views of the funded vaccinations in pharmacies, and how this policy worked in practice. Enablers and barriers to vaccination by pharmacists were explored. Interviews were transcribed and analysed using a framework approach. Results: Fifty-three interviews were conducted. Most women and health care professionals viewed funded maternal vaccinations in pharmacies positively with respect to increasing awareness and providing delivery options. Many women received messages from pharmacies. Most pharmacies used posters, leaflets and/or verbal explanation to pregnant women to raise awareness of the vaccinations. Not all pharmacies provided these vaccinations, and frontline staff could help to raise awareness. Conclusion: Funded maternal vaccinations in pharmacies are generally well accepted and provide an opportunity to increase uptake and prevent disease.

Paediatric hospitalizations due to whooping cough in Spain (1997-2017)

This epidemiological survey estimates the burden of whooping cough in infants up to 12 months old in Spain during a twenty-one-year period (1997-2017). The survey was conducted by reviewing data from the Spanish Surveillance System for Hospital Data. All hospitalizations due to whooping cough for infants, reported during the 1997-2017 period, were analysed. Codes were selected from the International Classification of Diseases, 9th Revision, Clinical Modification diagnosis codes 033.0-033.9. To explore the latest national outbreak and the implementation of vaccination in pregnant women, analyses were stratified to compare the following periods: 1997-2010, 2011-2015 and 2016-2017. A total of 13,352 hospital discharges for whooping cough in infants up to 12 months old were reported. A total of 6850 discharges in the period 1997-2010, 5271 in the period 2011-2015 and 1231 in 2016-2017 were identified. The annual hospitalization rate prior to 2011 was 131.02 cases per 100,000 infants; in 2011-2015, the rate was significantly higher (250.13 cases per 100,000 infants) and in 2016-2017 it decreased (157.69 cases per 100,000 infants). Most of the cases (n = 11,446) occurred in infants under 4 months of age, with hospitalization rates of 328.80, 670.81 and 385.84 cases per 100,000 infants up to 4 months of age in the periods 1997-2010, 2011-2015 and 2016-17, respectively. Thirty-four deaths occurred in the period 1997-2010, 36 in the period 2011-2015 and 4 in 2016-2017. All of the deaths occurred in infants under 4 months old. The case fatality rate did not vary significantly across the study periods. Whooping cough infections concentrate in infants up to 4 months of age in Spain. Public health measures such as vaccination of pregnant women, caregivers, health care professionals and relatives, especially young parents, could reduce the hospitalization burden during the current outbreak.