Influenza vaccination during early pregnancy and risk of major birth defects, US Birth Defects Study To Evaluate Pregnancy exposureS, 2014-2019

PURPOSE

Studies of influenza vaccination during pregnancy and major birth defects generally provide reassuring findings. To maintain public confidence, it is important to continue evaluating the safety of maternal vaccination using well characterized, population-based data. This study extended previous research to examine associations between maternal influenza vaccination and selected birth defects using data from the Birth Defects Study To Evaluate Pregnancy exposureS, a US, multisite case-control study.

METHODS

Mothers of case children (diagnosed with a birth defect) and control children (without a birth defect diagnosis) were identified from population-based birth defect surveillance programs and recruited to complete a telephone interview. Data from 2675 case and 1575 control mothers (participants) with deliveries during 2014-2019 were analyzed. Influenza vaccination exposure during the critical exposure period (one month before pregnancy through the first pregnancy month [B1P1] for spina bifida or through the third pregnancy month [B1P3] for other selected birth defects) was assessed controlling for several participant covariates. Logistic regression with propensity score adjustment was used to estimate adjusted odds ratios (aORs) and 95 % confidence intervals (CIs). Several secondary analyses were conducted. A probabilistic bias analysis examined the effect of exposure misclassification.

RESULTS

The aOR observed between B1P1 influenza vaccination exposure and spina bifida was 0.9 (95 % CI: 0.4-2.0). The aORs for B1P3 exposure and other selected birth defects examined ranged from 0.4 to 1.3, with 95 % CIs including the null except those for cleft lip ± cleft palate (aOR: 0.6; 95 % CI: 0.4-0.9) and gastroschisis (aOR: 0.4; 95 % CI: 0.2-0.7). Results from secondary analyses were similar to the primary analyses, and those from probabilistic bias analysis were similar to respective primary and secondary analyses.

CONCLUSION

Findings showed no statistically significant positive associations between influenza vaccination and the selected birth defects, supporting public health efforts to promote optimal vaccination coverage among pregnant women.

Vaccine Hesitancy in Women's Health

The development of vaccines is considered one of the greatest breakthroughs of modern medicine, saving millions of lives around the world each year. Despite vaccines' proven success, vaccine hesitancy remains a major issue affecting vaccine uptake. Common themes exist in patients' apprehension to receive vaccines. Women's health providers possess an important role in addressing these concerns and dispelling common misconceptions that may increase vaccine hesitancy thereby reduce vaccine uptake. This review aims to explore many of these topics as they are related to women's health and provide strategies for providers to implement which may reduce vaccine hesitancy among our patients.

Vaccine uptake and barriers to vaccination among at-risk adult populations in the US

To reduce morbidity and mortality associated with vaccine-preventable diseases (VPD), it is imperative that vaccination programs are implemented and prioritized throughout all stages of life across all populations. This study aimed to determine vaccine uptake and barriers to vaccination against VPDs among at-risk adult populations in the United States. We conducted a systematic literature review for articles published between January 2010 and June 2020 and identified 153 publications. The review identified 17 at-risk populations. Vaccine uptake was suboptimal among many populations, with factors including age, gender, and disease severity, associated with uptake. This review identified several barriers that impact vaccine uptake among at-risk populations, with concerns over safety, vaccine costs, lack of insurance, and lack of provider recommendation commonly reported across populations. Embracing a national life-course immunization framework that integrates developing policies, guidelines, and education would be a step to addressing these barriers.

Monitoring of Influenza Vaccination Coverage among Pregnant Women in Germany Based on Nationwide Outpatient Claims Data: Findings for Seasons 2014/15 to 2019/20

Pregnant women and their infants are at increased risk for severe influenza-related complications. A decade has passed since influenza vaccination was first recommended for pregnant women in Germany in 2010; however, monitoring of vaccination coverage (VC) has not yet been implemented for this target group. Using nationwide outpatient claims data, we here provide results on influenza VC among pregnant women in Germany for seasons 2014/15 to 2019/20. For any given season, pregnant women were defined as women who had undergone prenatal health care in at least two consecutive quarters within a season. VC increased from 9.0% in season 2014/15 to 16.6% in 2019/20 (+84%), while most of the increase occurred from season 2016/17 (VC: 9.9%) onwards (+68%). Consistently across seasons, women in east Germany were 40 to 60% more likely to be vaccinated compared to women residing in west Germany. According to age, the highest VC was observed among women aged 35 to <40 years (2019/20: 18.2%). Despite noticeable increases in influenza VC during recent years, overall coverage remains low among pregnant women. Starting with this analysis, VC among pregnant women in Germany will be monitored on a yearly basis in order to detect trends and identify immunization gaps.

Individual and Neighborhood Factors Associated With Failure to Vaccinate Against Influenza During Pregnancy

Uptake of influenza vaccine among pregnant women remains low. We investigated whether unvaccinated pregnant women were clustered geographically and determined factors associated with failure to vaccinate using spatial and multivariate logistic regression analyses. Pregnant women who were members of Kaiser Permanente Northern California in 2015 or 2016 were included in the study. More than half (53%) of the 77,607 included pregnant women were unvaccinated. Spatial analysis identified 5 clusters with a high prevalence of unvaccinated pregnant women. The proportion of unvaccinated women ranged from 57% to 75% within clusters as compared with 51% outside clusters. In covariate-adjusted analyses, residence in a cluster was associated with a 41% increase in the odds of being unvaccinated (odds ratio (OR) = 1.41, 95% confidence interval (CI): 1.36, 1.46). The odds of being unvaccinated were greater for Black women (OR = 1.58, 95% CI: 1.49, 1.69), Hispanic women (OR = 1.15, 95% CI: 1.05, 1.25), women with subsidized health insurance (OR = 1.18, 95% CI: 1.11, 1.24), women with fewer than 5 prenatal-care visits (OR = 1.85, 95% CI: 1.60, 2.16), and neighborhoods with a high deprivation index (fourth quartile vs. first: OR = 1.14, 95% CI: 1.07, 1.21). In conclusion, unvaccinated pregnant women were clustered geographically and by key sociodemographic factors. These findings suggest that interventions to increase influenza vaccine coverage among pregnant women are needed, particularly in vulnerable populations.

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

INTRODUCTION

At present, pregnant women in the U.S. are recommended to receive tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) and influenza vaccines. This study assessed maternal coverage of these 2 vaccinations.

METHODS

Data for this retrospective cohort study were extracted from 2 large administrative claims databases, the MarketScan Commercial and Multi-State Medicaid Databases, for 2009-2017 and analyzed in 2018. Women aged 15-44 years on the date of pregnancy end were included. Pregnancies with gestational age of less than 23 weeks were excluded from the Tdap vaccination endpoint owing to the optimal recommended gestational age for Tdap vaccination. Multivariable logistic regression models identified predictors of vaccination.

RESULTS

The Tdap vaccination subpopulation included 1,421,452 Commercial and 523,635 Medicaid pregnancies; the influenza vaccination subpopulation included 1,862,705 Commercial and 628,079 Medicaid pregnancies. There were marked increases in vaccination coverage from 2010 to 2017: from 1.0% to 56.3% (Commercial) and from 0.5% to 31.4% (Medicaid) for Tdap, and from 14.7% to 31.3% (Commercial) and from 9.7% to 17.5% (Medicaid) for influenza. The likelihood of Tdap/influenza vaccination increased significantly with receipt of the other vaccine and more pregnancy-related healthcare visits.

CONCLUSIONS

Although maternal Tdap and influenza vaccination coverage increased substantially from 2010 to 2017 among large, geographically diverse U.S. cohorts, coverage remained suboptimal, potentially putting newborns at risk of pertussis and influenza. Strategies to increase maternal vaccination coverage could target women identified to have a reduced likelihood of vaccination: those who are younger, black, residing in rural areas, with multiple gestation, and a prepregnancy inpatient admission.

Knowledge and Attitudes about the Flu Vaccine among Pregnant Women in the Valencian Community (Spain)

Background and Objectives: To describe the knowledge and attitudes related to the acceptance of the flu vaccine during pregnancy in women, from two Health Departments of the Valencian Community (VC), during the 2015–2016 season, after receiving prenatal care. Materials and Methods: A prospective observational study was conducted during the annual vaccine season of women ascribed to prenatal care. A midwife offered flu vaccine advice and afterwards conducted a telephone poll of a representative sample, in order to find out the reason for accepting or rejecting the vaccine. Results: Of the 1017 expectant women who received advice about the vaccine, 77.4% (95% CI: 74.8–79.9%) declared their intention to vaccinate. After the recommendation, the vaccine coverage was 61.6%, with a percentage of accordance of 98.8% (95% CI: 98.0–99.6%) between the coverage declared and the Nominal Vaccination Registry (NVR) of the VC. Additionally, 67.2% of the expectant women were interviewed (n = 683). Most were aware of the recommendation and identified the health center and the midwife as the main sources of information. The internet was a consistent source in favor of vaccination 80.8% (n = 42). The obstetric variables (risk during the pregnancy, end of pregnancy, and feeding the newborn) did not have a statistically significant relationship with the vaccination. The women declared a high adherence to the vaccinations present in the child vaccination calendar, but rejected (31.3%) the flu vaccine, as they had not received it previously and did not want it because of their expectant state. Conclusions: The women positively evaluated the effectiveness and safety of the vaccines. However, with the flu vaccine, “not being previously vaccinated” and the “doubts about its safety” represented more than half of the reasons put forth for its rejection. Ensuring that the flu vaccine is perceived as more effective and acceptable through the messages directed towards the expectant mothers, directly through the midwives or through the communication media and social networks, will result in an increase of vaccine coverage.

Oseltamivir exposure in pregnancy and the risk of specific birth defects

BACKGROUND

Influenza during pregnancy contributes to maternal morbidity and mortality. Neuraminidase inhibitors, including oseltamivir, are recommended for treating women with influenza during pregnancy.

METHODS

Data from the Slone Birth Defects Study from 2009 to 2015 were used to investigate associations between oseltamivir and specific birth defects. We classified exposures according to timing in pregnancy and examined 52 and 16 defects with early and potential late pregnancy etiology, respectively; we calculated crude odds ratios (ORs) and 95% confidence intervals (CIs) for defects with three or more exposures.

RESULTS

Among 8,379 cases and 4,190 nonmalformed controls, we identified 79 and 42 oseltamivir exposures, respectively. The majority of defects had no exposures. ORs were elevated for several defects, but the CI excluded the null only for intestinal malrotation (OR: 10.7 [1.8, 45.2]; three exposures).

CONCLUSIONS

Largely null findings for specific defects are reassuring. The association with intestinal malrotation, while unstable, warrants further investigation.

Effectiveness of a multimodal intervention to increase vaccination in obstetrics/gynecology settings

OBJECTIVE

To test the effectiveness of a multimodal intervention in obstetrics/gynecology (ob-gyn) clinics to increase uptake of influenza and tetanus-diphtheria-acellular pertussis (Tdap) vaccines in pregnant women and these vaccines plus human papillomavirus (HPV) vaccine in non-pregnant women.

METHODS

A cluster randomized controlled trial among 9 private ob-gyn practices in Colorado from 9/2011 to 5/2014. The intervention consisted of: designation of immunization champions, staff/provider trainings, assistance with vaccine purchasing/management, identification of eligible patients, standing order implementation, chart review/feedback, and patient education materials. Control practices continued usual care. Primary outcomes were receipt of influenza and Tdap vaccines among pregnant women and these vaccines plus HPV vaccine among non-pregnant women, comparing a Baseline period (Year 0/Year 1) to Year 2, intervention versus control. With an estimated sample size of 32,590 per arm, there would be >80% power to detect a 10% difference between groups.

RESULTS

In the Baseline period, 27% of pregnant women in both intervention and control practices received influenza vaccine. In Year 2, 29% of pregnant women in intervention practices received influenza vaccine versus 41% in control practices. In the Baseline period, 18% of pregnant women in intervention practices received Tdap vaccine versus 22% in control practices. Both intervention and control practices increased to 51% in Year 2, representing an increase of 33% for intervention practices and 29% for control practices, consistent with a change in Tdap recommendations. Relatively few HPV, influenza or Tdap vaccines (≤6% of eligible patients) were given to non-pregnant patients in either intervention or control practices at any time during the study.

CONCLUSION

In this cluster randomized trial designed to increase vaccination uptake, both intervention and control practices showed improved vaccination of pregnant but not non-pregnant patients. Future work should focus on tailoring evidence-based immunization practices or developing new approaches to specifically fit busy ob-gyn offices.