Maternal Influenza Vaccination Research Articles

Preventing Influenza Virus Infection and Severe Influenza Among Pregnant People and Infants.

The landscape of research on the benefits of influenza vaccines and antivirals to protect pregnant persons and infants has increased in recent years, while influenza vaccination rates and antiviral usage have declined. Pregnant people and infants <6 months of age are at increased risk of hospitalization with influenza, making protection of this population essential. Maternal influenza vaccination at any time during pregnancy is the best way to reduce the risk of influenza and severe influenza in both pregnant people and their infants <6 months of age. Influenza antiviral medications for pregnant people and infants are also recommended as early as possible if influenza is confirmed or suspected. This report will update on the current research on the benefits of influenza vaccination during pregnancy and influenza antiviral medication for the pregnant person and infant, current Advisory Committee on Immunization Practices recommendations for influenza vaccination in pregnancy and vaccination coverage rates, current influenza antiviral medication guidance and usage rates in pregnancy and among infants, and future directions for influenza pregnancy research. With over half a century of maternal influenza vaccination in the United States, we have improved protection for pregnant persons and infants against influenza, but we still have room for improvement and optimization with new challenges to overcome following the COVID-19 pandemic. By continuing to fill research gaps and increase vaccination coverage and antiviral usage, there is potential for significant reductions in the domestic and global burden of influenza in pregnant persons and infants.

Knowledge, attitudes, awareness and factors associated with the uptake of influenza vaccine among pregnant women in urban Pune

: This cross-sectional study was aimed to assess the knowledge, attitudes, awareness, facilitators, and barriers associated with the uptake of influenza vaccination during pregnancy in the urban area of Pune. : The study was conducted with 500 participants: 62 pregnant women and 438 postpartum women (total 524 were approached) attending Obstetrics and Gynaecology outpatient department (OPD) in a tertiary-care municipal hospital in Pune. The study-questionnaire collected data regarding socio-demographics general knowledge about influenza, attitude towards influenza vaccination, vaccine risk awareness, and its potential risk and benefits during pregnancy. The log-binomial regression models were used to examine the factors associated with influenza vaccination. : A good uptake of the vaccine (223/500, 44.6%) was found during current pregnancy of the participant; however, only 2.7% of study-participants vaccinated with influenza vaccine in their previous pregnancies. Also, there was poor awareness among all the participants regarding the safety of the seasonal influenza vaccine during pregnancy (19%, n=95/500). 11.2% (n=31/277) study-participants were found to be against the maternal influenza vaccination. Women receiving the vaccine against influenza were more likely to be previously informed of the recommendations from health-care providers about maternal influenza vaccination with odds ratio of 0.18 (95% CI, 0.04 to 0.8; p&amp;#60;0.00001), received the influenza vaccine in the past OR 8.27 (95% CI, 0.94 to 72.0), Z 1.09, p=0.05 and of having knowledge on influenza and its complications has more impact on influenza vaccination during pregnancy OR 14.4 (95% CI, 5.68 to 36.53), Z 5.6, p&amp;#60;0.0001 respectively.: This study concludes the vital causative factors for non-vaccination were provision of incomplete information or poor awareness about influenza vaccination (68.6%). There was poor knowledge among the pregnant women regarding the safety of maternal influenza vaccines. The recommendation from healthcare professionals is the major facilitators of decision-making by pregnant women for influenza vaccination during pregnancy.

Effect of maternal vaccination on infant morbidity in Bangladesh

BackgroundRisk factors of infant mortality in Africa and south Asian countries have been broadly discussed. However, infant morbidity is largely underestimated. We analyzed the data from a randomized vaccine trial in Bangladesh to identify and assess the effect of risk factors on infant morbidity.MethodsPregnant women were randomly assigned to receive either inactivated influenza vaccine or pneumococcal polysaccharide vaccine and the infants were randomly assigned to receive 7-valent pneumococcal conjugate vaccine or Hib conjugate vaccine at week 6, 10 and 14. The data were collected from August 2004 through December 2005. Each pair of infant and mother were followed for 24 weeks after birth with weekly visits. Generalized estimating equations (GEE) for repeated measurements and Poisson regression models were used to identify the risk factors and evaluate their effect on the longitudinal incidence and total number of episodes of respiratory illness with fever (RIF), diarrhea disease, ear problem and pneumonia.ResultsA total of 340 pregnant women were randomized with mean age of 25 years. The baseline mother and infant characteristics were similar between two treatment groups. Exclusive breastfeeding and higher paternal education level were common factors associated with lower infant morbidity of RIF (adjusted OR = 0.40 and 0.94 with p < 0.01 and p = 0.02, respectively), diarrhea disease (adjusted OR = 0.39 and 0.95 with p < 0.01 and p = 0.04, respectively), and ear problem (adjusted OR = 0.20 and 0.76 with p < 0.01 and p < 0.01, respectively). Maternal influenza vaccine significantly reduced the incidence of RIF (adjusted OR = 0.54; p < 0.01) but not diarrhea disease or ear problem (p > 0.05). Female infants had lower incidence of diarrhea disease (adjusted OR = 0.67; p = 0.01) and ear problem (adjusted OR = 0.12; p = 0.01).ConclusionsMaternal influenza vaccination, exclusive breastfeeding, female children, and higher paternal education level significantly reduced the infant morbidity within the 24 weeks after birth in Bangladesh.

Effectiveness of Maternal Influenza Vaccination During Pregnancy Against Influenza-Associated Emergency Department Visits and Hospitalizations in Infants

Effectiveness of Maternal Influenza Vaccination During Pregnancy Against Influenza-Associated Emergency Department Visits and Hospitalizations in Infants <6 Months of Age

Influenza vaccine during pregnancy, recommendations from healthcare providers, and race/ethnicity in the United States.

We examined racial/ethnic differences in the association between influenza vaccine recommendations from healthcare providers and maternal vaccination uptake. This cross-sectional study examined data from the Pregnancy Risk Assessment Monitoring System. We categorized respondents as non-Hispanic (NH) Whites, NH-Blacks, NH-Asians, American Indians/Alaska Natives, NH Other non-Whites, and Hispanics. We conducted multivariable logistical regression models to evaluate adjusted odds ratios (AOR) and 95% confidence intervals (CI). Covariates included maternal age, marital status, education, insurance status before pregnancy, the number of previous live births, the number of prenatal care visits, and smoking status during pregnancy. The prevalences of receiving influenza vaccine recommendations from healthcare providers and maternal vaccine were 80.01% and 50.42%, respectively. NH-Blacks are less likely to receive provider recommendations (AOR = 0.82; 95%CI 0.77-0.87) and be vaccinated (AOR = 0.76; 95%CI 0.72-0.80) than NH-Whites. Receiving provider recommendations was significantly associated with increased maternal influenza vaccine uptake (AOR = 15.50; 95% CI 14.51-16.55). The associations were significant for all racial/ethnic groups, with the highest among NH-Asians (AOR = 22.04; 95% CI 17.88-27.16) and the lowest among NH Other non-Whites (AOR = 11.07; 95% CI 8.25-14.86). Within NH-Asians, effectiveness among Chinese was highest (AOR = 29.39; 95% CI 18.10-47.71). Racial/ethnic disparities in maternal influenza vaccine uptake and receiving vaccine recommendations from healthcare providers persisted. Further studies on the racial/ethnic disparities in maternal vaccination were warranted and tailored strategies are required to reduce this health disparity.

Maternal Vaccine Effectiveness Against Influenza-Associated Hospitalizations and Emergency Department Visits in Infants

Influenza virus infection during pregnancy is associated with severe maternal disease and may be associated with adverse birth outcomes. Inactivated influenza vaccine during pregnancy is safe and effective and can protect young infants, but recent evidence, particularly after the 2009 novel influenza A (H1N1) pandemic, is limited. To evaluate the effectiveness of influenza vaccination during pregnancy against laboratory-confirmed influenza-associated hospitalizations and emergency department (ED) visits in infants younger than 6 months. This was a prospective, test-negative case-control study using data from the New Vaccine Surveillance Network from the 2016 to 2017 through 2019 to 2020 influenza seasons. Infants younger than 6 months with an ED visit or hospitalization for acute respiratory illness were included from 7 pediatric medical institutions in US cities. Control infants with an influenza-negative molecular test were included for comparison. Data were analyzed from June 2022 to September 2023. Maternal influenza vaccination during pregnancy. We estimated maternal vaccine effectiveness against hospitalizations or ED visits in infants younger than 6 months, those younger than 3 months, and by trimester of vaccination. Maternal vaccination status was determined using immunization information systems, medical records, or self-report. Vaccine effectiveness was estimated by comparing the odds of maternal influenza vaccination 14 days or more before delivery in infants with influenza vs those without. Of 3764 infants (223 with influenza and 3541 control infants), 2007 (53%) were born to mothers who were vaccinated during pregnancy. Overall vaccine effectiveness in infants was 34% (95% CI, 12 to 50), 39% (95% CI, 12 to 58) against influenza-associated hospitalizations, and 19% (95% CI, -24 to 48) against ED visits. Among infants younger than 3 months, effectiveness was 53% (95% CI, 30 to 68). Effectiveness was 52% (95% CI, 30 to 68) among infants with mothers who were vaccinated during the third trimester and 17% (95% CI, -15 to 40) among those with mothers who were vaccinated during the first or second trimesters. Maternal vaccination was associated with reduced odds of influenza-associated hospitalizations and ED visits in infants younger than 6 months. Effectiveness was greatest among infants younger than 3 months, for those born to mothers vaccinated during the third trimester, and against influenza-associated hospitalizations.

1012. Protective Effects of Maternal Influenza Vaccine during Pregnancy and Breastfeeding on Risk of Infant Influenza

Abstract Background Children &amp;lt; 6 months of age are not eligible for influenza vaccine but are at high risk of influenza and its complications. Maternal influenza immunization (MII) in pregnancy or during lactation are two ways to provide infants vaccine specific influenza antibodies that could confer protection. Limited data delineate the individual and combined protective effects of MII and breastfeeding on influenza in infants. We aimed to evaluate the independent and combined protective effects of MII during pregnancy and breastfeeding against influenza during the first 6 months of life. Methods We utilized a retrospective cohort of mother-infant pairs, including infants born between January 1, 2012, to December 31, 2019 with longitudinal care within a single health system. Maternal influenza vaccine, breastfeeding and important covariates (Table 1) were obtained from electronic health records. We evaluated the odds of laboratory-confirmed influenza among infants &amp;lt; 6 months of age based on MII in pregnancy and breastfeeding status at 3 months of age using unadjusted and adjusted logistic regression following stepwise regression for covariates with p-value &amp;lt; 0.15. Results Of the 44,132 mother-infant pairs included, 0.3% (N=141) of infants had laboratory-confirmed influenza between birth and 6 months of age. 54% of infants received some/exclusive breastmilk at 3 months of age; 51% of mothers had MII during pregnancy. Breastfeeding alone (aOR: 0.77; 95%CI: 0.51-1.16) did not significantly protect against influenza compared to infants who received no breastmilk and no MII. In contrast, exposure to MII trended toward decreased risk of influenza by 37% (aOR: 0.63; 95%CI: 0.39-1.01), and the combination of MII in pregnancy and breastfeeding significantly decreased odds of infant influenza by 60% (aOR: 0.40; 95%CI: 0.25-0.66) (Table 1). Conclusion MII in pregnancy can effectively reduce the risk of influenza between 40-60% in children &amp;lt; 6 months. Breastfeeding significantly enhances that protection, either through its broad immune properties and/or the vaccine-specific antibodies in milk. Increasing the administration and acceptance of MII in pregnancy and improving sustained breastfeeding rates may help reduce the burden of infant influenza. Disclosures John V. Williams, MD, Merck: Grant/Research Support|Quidel: Board Member Judith M. Martin, MD, Merck, Sharp and Dhome: Grant/Research Support

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

BackgroundAssessment 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. ObjectiveTo 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. MethodsFemale 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. ResultsOf 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. ConclusionsIn 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.

Factors Associated with Early Versus Late Uptake of the COVID-19 Vaccine during Pregnancy over Time in Australia: A Population-Based Cohort Study.

Pregnant women are at an increased risk of hospitalisation, admission to the intensive care unit, mechanical ventilation, and death from SARS-CoV-2 infection. The aim of this study is to determine the predictive factors associated with COVID-19 vaccine uptake during pregnancy over time in a population with a high background uptake of maternal influenza and pertussis vaccination. This is a population-based, cohort study of all pregnant women who gave birth in Victoria, Australia between 1 July 2021 and 30 June 2022. Data from the Victorian Perinatal Data Collection were analysed using univariable and multivariable logistic regression. This study reports on 77,719 women who gave birth over a 12 month period, of whom 49,281 (63.4%) received a COVID-19 vaccine, 54,887 (70.6%) received an influenza vaccination and 63,594 (81.8%) received a pertussis vaccine by the time of delivery. Pregnant women aged >30 years (aOR 1.31 CI 1.27, 1.36), who had >=8 antenatal visits (aOR 1.08 CI 1.04, 1.12), and those who received influenza vaccine (aOR 1.23 CI 1.19, 1.28) were more likely to have received a COVID-19 vaccine. Those who smoked (aOR 0.7 CI 0.66, 0.74), were First Nations (aOR 0.83 CI 0.74, 0.93) and those who gave birth in public hospitals (aOR 0.65 CI 0.63, 0.68) were less likely to receive COVID-19 vaccine in the first 12 months of the rollout. Maternal age, smoking, parity and Indigenous status were factors associated with delayed and sustained lower coverage, even in a population with background maternal influenza and pertussis coverage of 70.6% and 81.8%, respectively.

Assessing the Presence of IgG Antibodies against Influenza Viruses in Neonates after Maternal Vaccination and Factors That May Affect the Transplacental Transfer.

Special populations, particularly pregnant women, are uniquely susceptible to infectious diseases due to alterations in their immunological, respiratory, and cardiovascular systems during gestation. Influenza infections during the perinatal period have been associated with more severe maternal and perinatal outcomes, underscoring the critical importance of vaccination data for pregnant women. According to the World Health Organization (WHO), all pregnant women and those of childbearing age should receive the inactivated influenza vaccine, irrespective of their pregnancy stage. This study aimed to elucidate factors influencing neonatal antibody presence following maternal influenza vaccination. Conducted through convenience sampling in Athens, Greece, this study involved 78 pregnant women who received flu vaccinations. The participants completed questionnaires covering demographics, obstetric history, attitudes toward influenza vaccination, and knowledge about the influenza virus and pregnancy vaccination. Blood samples were collected from 83 neonates to assess IgG antibody presence. Five of the surveyed women had twin pregnancies. The statistical analysis employed IBM SPSS-Statistics version 26.0. This study revealed the presence of positive influenza A and B antibodies in neonates following maternal immunization. Furthermore, it identified factors such as the gestational week and timing of vaccination during pregnancy that influenced the transfer of antibodies from mother to fetus. These findings offer valuable insights for healthcare professionals to provide informed recommendations on influenza vaccination during pregnancy and empower expectant mothers to make informed decisions about the benefits of immunization.

Web-based intervention for improving influenza vaccination in pregnant women: a cost-effectiveness analysis

ABSTRACT A website with vaccine information and interactive social media was reported to improve maternal influenza vaccine uptake. This study aimed to evaluate cost-effectiveness of a web-based intervention on influenza vaccine uptake among pregnant women from the perspective of US healthcare providers. A one-year decision-analytic model estimated outcomes in a hypothetical cohort of pregnant women with: (1) website with vaccine information and interactive social media (intervention group), and (2) usual care (usual care group). Primary measures included influenza infection, influenza-related hospitalization, mortality, direct medical cost, and quality-adjusted life-year (QALY) loss. In base-case analysis, intervention group reduced cost (by USD28), infection (by 28 per 1,000 pregnant women), hospitalization (by 1.226 per 1,000 pregnant women), mortality (by 0.0036 per 1,000 pregnant women), and saved 0.000305 QALYs versus usual care group. Relative improvement of vaccine uptake by the intervention and number of pregnant women in the healthcare system were two influential factors identified in deterministic sensitivity analysis. The intervention was cost-effective in 99.5% of 10,000 Monte Carlo simulations (at willingness-to-pay threshold 50,000 USD/QALY). A website with vaccine information and interactive social media to promote influenza vaccination for pregnant women appears to reduce direct medical costs and gain QALYs from the perspective of US healthcare providers.

Transplacental transfer efficiency of maternal antibodies against influenza A(H1N1)pdm09 virus and dynamics of naturally acquired antibodies in Chinese children: a longitudinal, paired mother–neonate cohort study

The 2009 pandemic H1N1 influenza A virus (A(H1N1)pdm09 virus) evolves rapidly and has continued to cause severe infections in children since its emergence in 2009. We aimed to characterise the kinetics of maternally and naturally acquired antibodies against historical A(H1N1)pdm09 strains and to assess the extent to which the response to heterologous strains following infection or vaccination affects observed A(H1N1)pdm09 strain-specific antibody titres in a Chinese paediatric population. In this retrospective study, we used residual serum samples from 528 mother-neonate pairs from a non-interventional, longitudinal cohort study in southern China conducted from Sept 20, 2013, to Aug 24, 2018, from six local hospitals in Anhua County, Hunan Province, China. Mother-neonate pairs were eligible for inclusion if the neonates were born after Sept 20, 2013, and their mothers had resided in the study sites for at least 3 months. We tested samples with a haemagglutination inhibition (HAI) assay to measure antibody levels against three historical A(H1N1)pdm09 strains that were antigenically similar to the strains that circulated during the 2009 pandemic (A/Hunan-Kaifu/SWL4204/2009 [SWL4204/09 strain], A/Hunan-Daxiang/SWL1277/2016 [SWL1277/16 strain], and A/Hunan-Yanfeng/SWL185/2018 [SWL185/18 strain]). We also determined the seroprevalence, geometric mean titres (GMTs), transfer ratio of maternal antibodies, and the dynamics of maternally and naturally acquired antibodies in children, from birth to 3 years of age. 1066 mother-neonate pairs were enrolled in the original cohort between Sept 20, 2013, and Oct 14, 2015. Of these, 528 pairs (523 mothers, 528 neonates) were selected for the present study. The median age of the mothers was 25 years (IQR 23 to 29). 291 (55%) of 528 children were boys and 237 (45%) were girls, and most children (452 [86%]) were breastfed before the age of 6 months. The GMTs and the seroprevalence for the SWL4204/09 strain were higher than those for the SWL1277/16 and SWL185/18 strains among mothers (GMTs: 10·4 [95% CI 9·8 to 11·1] vs 9·3 [8·7 to 9·8] vs 8·0 [7·5 to 8·4], p<0·0001; seroprevalence: 11·1% [95% CI 8·5 to 14·1] vs 6·9% [4·9 to 9·4] vs 4·6% [3·0 to 6·8], p=0·0003) and among neonates (GMTs: 10·7 [10·0 to 11·5] vs 9·4 [8·8 to 10·0] vs 8·1 [7·6 to 8·6], p<0·0001; seroprevalence: 13·4% [10·7 to 16·7] vs 8·7% [6·5 to 11·5] vs 6·1% [4·2 to 8·5], p=0·0002). Regardless of the A(H1N1)pdm09-specific strain, maternal antibodies could be transferred efficiently via the placenta (mean transfer ratios: 1·10 for SWL4204/09 vs 1·09 for SWL1277/16 vs 1·06 for SWL185/18; p=0·93). The A(H1N1)pdm09 strain-specific antibodies waned below the protective threshold of 1:40 within 2 months after birth. After maternal antibody waning, there were periodic increases and decreases in HAI antibody titres against three A(H1N1)pdm09 strains, and such increases were all significantly associated with a higher immune response to heterologous strains. Vaccination against the SWL4204/09 strain was associated with a poor response to the SWL185/18 strain (β-0·20, 95% CI -0·28 to -0·13; p<0·0001). Our findings suggest low pre-existing immunity against influenza A(H1N1)pdm09 virus among unvaccinated Chinese adult female and paediatric populations. This evidence, together with the rapid decay of maternal antibodies and the observed cross-reactivity among different A(H1N1)pdm09 strains, highlights the importance of accelerating maternal and paediatric influenza vaccination in China. The Key Program of the National Natural Science Foundation of China. For the Chinese translation of the abstract see Supplementary Materials section.

Antenatal interventions to reduce risk of low birth weight related to maternal infections during pregnancy

BackgroundMaternal infections during pregnancy have been linked to increased risk of adverse birth outcomes, including low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), and stillbirth (SB). ObjectivesThe purpose of this article was to summarize evidence from published literature on the effect of key interventions targeting maternal infections on adverse birth outcomes. MethodsWe searched MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and CINAHL Complete between March 2020 and May 2020 with an update to cover until August 2022. We included randomized controlled trials (RCTs) and reviews of RCTs of 15 antenatal interventions for pregnant women reporting LBW, PTB, SGA, or SB as outcomes. ResultsOf the 15 reviewed interventions, the administration of 3 or more doses of intermittent preventive treatment in pregnancy with sulphadoxine–pyrimethamine [IPTp-SP; RR: 0.80 (95% CI: 0.69, 0.94)] can reduce risk of LBW compared with 2 doses. The provision of insecticide-treated bed nets, periodontal treatment, and screening and treatment of asymptomatic bacteriuria may reduce risk of LBW. Maternal viral influenza vaccination, treatment of bacterial vaginosis, intermittent preventive treatment with dihydroartemisinin–piperaquine compared with IPTp-SP, and intermittent screening and treatment of malaria during pregnancy compared with IPTp were deemed unlikely to reduce the prevalence of adverse birth outcomes. ConclusionsAt present, there is limited evidence from RCTs available for some potentially relevant interventions targeting maternal infections, which could be prioritized for future research.

Influenza and pertussis vaccine coverage in pregnancy in Australia, 2016-2021.

Vaccination in pregnancy is the best strategy to reduce complications from influenza or pertussis infection in infants who are too young to be protected directly from vaccination. Pregnant women are also at risk of influenza complications preventable through antenatal vaccination. Both vaccines are funded under the National Immunisation Program for pregnant women in Australia, but coverage is not routinely reported nationally. We reviewed all reported Australian maternal influenza and pertussis vaccine coverage data for the period 2016-2021, to identify gaps and information needs. Maternal influenza vaccine coverage was suboptimal at < 58% for 2016-2018, with higher coverage of 62-75% reported in two states (Victoria and Western Australia) for 2019-2021. Maternal pertussis vaccine coverage from 2016 was generally higher than for influenza at > 70%, with the highest jurisdictional coverage of 89% reported in Western Australia in 2020. Vaccination rates were often suboptimal among First Nations pregnant women and up to 20% lower than among non-First Nations Australian women; while data were limited, coverage was low among culturally and linguistically diverse women and among women of lower socio-economic status. Jurisdictional perinatal data collections were the best source of information on antenatal vaccine coverage but were only available for a minority of the population; a nationally consistent systematic approach is lacking. Timely and comprehensive data are needed to provide feedback to improve maternal vaccination coverage, particularly among groups with higher risk and/or low uptake, and as new vaccines are recommended, including COVID-19 vaccination.

Safety and Protective Effects of Influenza Vaccination in Pregnant Women on Pregnancy and Birth Outcomes in Pune, India: A Cross-Sectional Study.

Maternal influenza vaccination provides effective protection against influenza infections in pregnant women and their newborns. In India, the influenza vaccine has not yet been offered through immunization programs, owing to the lack of sufficient safety data for pregnant Indian women. This cross-sectional observational study enrolled 558 women admitted to the obstetrics ward of a civic hospital in Pune. Study-related information was obtained from the participants through hospital records and interviews using structured questionnaires. Univariate and multivariable analysis was used, and the chi-square test with adjusted odds ratio was estimated to account for vaccine exposure and the temporal nature of each outcome, respectively. Women not vaccinated against influenza during pregnancy had a higher risk of delivering very LBW infants, and possible protective effects were suggested (AOR 2.29, 95% CI 1.03 to 5.58, p = 0.03). No association was observed between maternal influenza vaccination for Caesarean section (LSCS) (AOR 0.97, 95% CI, 0.78, 1.85), stillbirth (AOR 1.8, 95% CI 0.18, 24.64) and NICU admission (AOR, 0.87, 0.29 to 2.85), and congenital anomaly (AOR, 0.81, 0.10 to 3.87). These results show that the influenza vaccine administered during pregnancy is safe and might lower the risk of negative birth outcomes.

Association between maternal influenza vaccination and neurodevelopmental disorders in childhood: a longitudinal, population-based linked cohort study

ObjectiveTo assess the association between in utero exposure to seasonal inactivated influenza vaccine (IIV) and the risk of a diagnosis of a neurodevelopmental disorder in early childhood.DesignRetrospective cohort study.SettingPopulation-based birth...

Acceptance of vaccination against pertussis, COVID-19 and influenza during pregnancy: a cross-sectional study

BackgroundThis study aims to assess the uptake of maternal pertussis and COVID-19 vaccination and the intention towards accepting the maternal influenza vaccination. Insights into different socio-demographic factors related to maternal vaccination coverage might help to address vaccine acceptance and improve maternal vaccine uptake in the future.MethodsWe conducted a cross-sectional survey among pregnant women and recent mothers, up to 6 months post-partum. The primary outcome measures of this study were behaviour for maternal pertussis and COVID-19 vaccination, and maternal influenza vaccination intention. Associations between socio-demographic factors and maternal pertussis vaccination and maternal COVID-19 vaccination behaviour; and socio-demographic factors and maternal influenza vaccination intention were assessed using binary logistic regression analyses.ResultsIn total 1361 respondents filled out the questionnaire. Almost all women (95%) were vaccinated against pertussis during pregnancy, while almost two-third were vaccinated against COVID-19 during pregnancy (58%) and almost one-third (28%) had a positive intention towards receiving the maternal influenza vaccination. Results show that young maternal age and low education level were associated with lower maternal vaccination acceptance.ConclusionVaccination campaigns focusing on the severity of diseases that are prevented, are needed to increase maternal vaccine acceptance in younger and low-educated pregnant women. We expect that differences in vaccination coverage between the three maternal vaccinations might partly be explained by existing recommendations, campaigns and whether the vaccination is part of the national immunisation program.

The association between maternal influenza vaccination during pregnancy and adverse birth outcomes in the United States: Pregnancy risk Assessment Monitoring System (PRAMS).

Influenza vaccination during pregnancy is highly recommended. We examined the association between maternal influenza vaccination and adverse birth outcomes. This cross-sectional study used data from the Pregnancy Risk Assessment Monitoring System (PRAMS) during 2012-2017. The primary exposure was the receipt of influenza vaccination during pregnancy. Low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA) were the primary outcomes. We conducted multivariable logistic regression models to estimate the adjusted odds ratios (AOR) and 95% confidence intervals (CI). Covariates used to adjust confounding included maternal age, marital status, education, race and ethnicity, insurance status before pregnancy, and smoking status. For a subgroup in 2012-2015, we analyzed the association between influenza vaccination in each trimester and adverse birth outcomes. During 2012-2017, compared with unvaccinated women, women vaccinated during pregnancy had a lower risk of LBW and PTB. During 2012-2015, maternal influenza vaccination in the 1st and 3rd trimesters was associated with a reduced risk of LBW and PTB, and vaccination in the 3rd trimester had a greater protective effect than in the 1st trimester. Influenza vaccination was not associated with SGA regardless of trimester. Our findings suggest that influenza vaccination during pregnancy is a safe and effective way to protect newborns.

Interventions to increase uptake of influenza vaccination in pregnancy: A systematic review and meta-analysis.

Maternal influenza vaccination has been introduced in several countries to prevent influenza-related morbidity and mortality in pregnant women, fetuses, and infants too young to be vaccinated. To analyze the available randomized controlled trials (RCTs) on the effectiveness of pregnant women-focused interventions to increase influenza vaccination uptake during pregnancy. Medline, CINAHL, Scopus, Web of Science, and Cochrane Trial were searched on August 25, 2021. RCTs assessing the effectiveness of pregnant women-focused interventions in increasing influenza vaccination among pregnant women were included. Two independent reviewers extracted data. A random-effects meta-analysis was conducted to estimate pooled odds ratios (ORs). Seven RCTs were selected. Overall, the interventions had a significant effect in increasing influenza vaccination during pregnancy compared with standard care (OR 1.78, 95% confidence interval [CI] 1.25-2.54; P= 0.001; I2 = 67%). However, subgroup analysis suggested that influenza vaccination uptake only was associated with educational interventions (OR 2.71, 95% CI 1.93-3.81; P< 0.001; I2 = 0%). We found that several educational interventions for pregnant women can effectively increase influenza vaccination uptake in this population. Specifically, pamphlets, websites, and brief one-to-one education can be effective tools. CRD42021269478.

The Pregnancy, Arsenic, and Immune Response (PAIR) Study in rural northern Bangladesh.

Arsenic exposure and micronutrient deficiencies may alter immune reactivity to influenza vaccination in pregnant women, transplacental transfer of maternal antibodies to the foetus, and maternal and infant acute morbidity. The Pregnancy, Arsenic, and Immune Response (PAIR) Study was designed to assess whether arsenic exposure and micronutrient deficiencies alter maternal and newborn immunity and acute morbidity following maternal seasonal influenza vaccination during pregnancy. The PAIR Study recruited pregnant women across a large rural study area in Gaibandha District, northern Bangladesh, 2018-2019. Prospective, longitudinal pregnancy and birth cohort. We conducted home visits to enrol pregnant women in the late first or early second trimester (11-17 weeks of gestational age). Women received a quadrivalent seasonal inactivated influenza vaccine at enrolment. Follow-up included up to 13 visits between enrolment and 3 months postpartum. Arsenic was measured in drinking water and maternal urine. Micronutrient deficiencies were assessed using plasma biomarkers. Vaccine-specific antibody titres were measured in maternal and infant serum. Weekly telephone surveillance ascertained acute morbidity symptoms in women and infants. We enrolled 784 pregnant women between October 2018 and March 2019. Of 784 women who enrolled, 736 (93.9%) delivered live births and 551 (70.3%) completed follow-up visits to 3 months postpartum. Arsenic was detected (≥0.02 μg/L) in 99.7% of water specimens collected from participants at enrolment. The medians (interquartile ranges) of water and urinary arsenic at enrolment were 5.1 (0.5, 25.1)μg/L and 33.1 (19.6, 56.5)μg/L, respectively. Water and urinary arsenic were strongly correlated (Spearman's ⍴=0.72) among women with water arsenic ≥ median but weakly correlated (⍴=0.17) among women with water arsenic < median. The PAIR Study is well positioned to examine the effects of low-moderate arsenic exposure and micronutrient deficiencies on immune outcomes in women and infants. NCT03930017.