Cross-sectional study on factors associated with influenza vaccine uptake and pertussis vaccination status among pregnant women in Germany

Pregnant women and their newborns are at increased risk for influenza-related complications; the latter also have an increased risk for pertussis-related complications. In Germany, seasonal influenza vaccination is recommended for pregnant women since 2010. A dose of pertussis-containing vaccine has been recommended since 2004 for women of childbearing age if they have not been vaccinated within the past 10 years. We conducted a nationwide cross-sectional survey among pregnant women in February/March 2013 to assess knowledge, attitudes, and practices related to influenza vaccination during pregnancy and to identify factors associated with their pertussis vaccination status. In total, 1025 pregnant women participated and provided information through a self-administered questionnaire. Of these, 23.2% were vaccinated against seasonal influenza during the 2012/13 season; 15.9% during their pregnancy. Major reasons for being unvaccinated (n = 686 respondents) were lack of confidence in the vaccine (60.4%) and the perception that vaccination was not necessary (40.3%). Influenza vaccination during pregnancy was independently associated with having received influenza vaccine in the previous season, having received a recommendation from a physician, a high level of vaccine-related knowledge and of perceived disease severity. In contrast, knowledge of the recommendation for regular hand-washing to prevent influenza and the perception that vaccine-related side effects were likely to occur or likely to be severe were negatively associated with vaccine uptake. Receipt of a pertussis vaccine in the past 10 years was reported by 22.5% of participants. Pertussis vaccine uptake was independently associated with living in the Eastern federal states and receiving seasonal influenza vaccination annually, while a migration background was associated with a lower uptake. To enhance vaccine uptake in pregnant women and women of childbearing age, special efforts must be undertaken to improve knowledge of both recommendations and the benefits of vaccination. Gynecologists could serve as important facilitators.     

Tetanus and diphtheria toxoids and acellular pertussis vaccine uptake during pregnancy in a metropolitan tertiary care center

ObjectivesTetanus, diphtheria and acellular pertussis (Tdap) vaccine is recommended during each pregnancy, but national uptake is poor. We assessed Tdap uptake in a tertiary referral hospital served by university-affiliated and private obstetrical offices.MethodsReview of women delivering at Texas Children's Hospital Pavilion for Women, Houston, Texas, during April 2013–June 2014.Results6577 deliveries occurred during the study period. Mean maternal age was 29.8 years (range 13–49); race/ethnicity was 43.6% White, 27% Hispanic, 21% Black, 7.1% Asian, and 1.3% other. 252 were multiple gestations; 229 sets of twins, 21 triplets and 2 quadruplets. 3678 (56%) women received Tdap during pregnancy, 249 (3.8%) postpartum and 100 (1.5%) received Tdap pre-conception only. Tdap uptake during pregnancy increased from 36% in April 2013 to a sustained uptake of greater than 61% since November 2013, with increases noted coincidental with presentations highlighting Tdap maternal immunization recommendations at faculty and staff meetings, and the release of the ACOG “toolkit”. When antenatal Tdap vaccine was administered, mean gestation at receipt of Tdap was 31.4 weeks and 95% of vaccinated women received Tdap at the recommended gestation interval of 27–36 weeks, 71.6% during the 28–32 week window believed optimal for placental transport and 98.5% at least 7 days before delivery. Of 19 women with two pregnancies during the study period, four (21%) had Tdap during both. Black women were less likely to receive antenatal Tdap than women of other race/ethnicity (41% versus 60%; P < 0.001).ConclusionsSustained antenatal Tdap uptake rates exceeding 61% were achieved after strategies to increase awareness of recommendations were introduced and 95% of women were immunized at a gestation optimal for efficient maternal antibody placental transport. Further increases in uptake will require system changes such as best practice alerts in electronic medical records.     

Determinants of influenza and pertussis vaccine uptake in pregnant women in Ireland: A cross-sectional survey in 2017/18 influenza season

In Ireland seasonal influenza and pertussis vaccination during pregnancy is recommended and every year national campaigns are organised to raise awareness and improve uptake. We estimated influenza and pertussis vaccine uptake and identified factors associated with vaccination status in pregnant women in 2017/18.We conducted a face-to-face omnibus survey, with quota sampling, among women aged 18–55 years and collected socio-demographic characteristics, self-reported vaccination status, awareness of vaccine campaigns, and attitudes towards vaccination. Sample was weighted to ensure representativeness with the target population. We performed univariate and multivariable logistic regression analyses on survey data.Overall, 241 pregnant women were enrolled. Influenza and pertussis vaccine uptake was 61.7% and 49.9%, respectively. Awareness of vaccine campaign and socio-economic status (SES) were associated with both influenza and pertussis vaccine uptake. The association between SES and uptake of vaccines differed by awareness. Women aware of the influenza vaccine campaign and with mid and low SES were less likely to be vaccinated, compared to those with high SES (aOR = 0.46; 95%CI: 0.22–0.97; aOR = 0.27; 95%CI: 0.12–0.60, respectively); women not aware of the pertussis vaccine campaign and with mid and low SES were less likely to be vaccinated, compared to those aware and with high SES (aOR = 0.15; 95%CI: 0.04–0.48; aOR = 0.05; 95%CI: 0.01–0.24, respectively).General practitioner (GP) recommendation was the main reason for receiving influenza vaccine (39.2%), and 71.8% of women were recommended pertussis vaccination from their GPs.The survey reports moderate uptake of vaccines among pregnant women, inequalities in uptake by SES and identifies GPs as primary source for vaccine recommendation. We recommend multifaceted campaigns, by engaging GPs, to target all socio-economic groups.     

Intention to accept pertussis vaccine among pregnant women in Karachi,Pakistan

BackgroundMaternal immunization against pertussis is a potential strategy to protect young infants from severe disease. We assessed factors associated with intention to accept pertussis vaccination among pregnant women in Karachi, Pakistan.MethodsWe conducted a cross-sectional survey between May and August 2013 in pregnant women who visited healthcare centers in urban slums of Karachi city. Women completed a survey examining socio-demographic factors, vaccination history, knowledge on pertussis disease, perception of vaccine recommendation sources, and potential influences on vaccine decision-making.ResultsOf the 283 participants, 259 (92%) provided their intention to either accept or decline pertussis vaccination. Eighty-three percent women were willing to accept the pertussis vaccine if offered during pregnancy. About half (53%) of the participants had ever heard of pertussis disease. Perceptions of pertussis vaccine efficacy, safety, and disease susceptibility were strongly associated with intention to accept pertussis vaccine (p < 0.01). Healthcare providers, Ministry of Health, and mass media were considered as highly reliable sources of vaccine recommendation and associated with intention to accept antenatal pertussis vaccination (p < 0.001). Healthcare provider recommendation was a common reason cited by respondents for pregnant women to accept antenatal pertussis vaccination (p = 0.0005). However, opinion of primary decision-makers in the family (husbands and in-laws) was a crucial reason cited by respondents for pregnant women to reject pertussis vaccination in pregnancy (p = 0.003).ConclusionAntenatal pertussis vaccination initiatives in South Asia should strongly consider inclusion of family members, healthcare providers, national health ministries, and mass media to help implement new vaccination programs.     

Evaluation of two vaccine education interventions to improve pertussis vaccination among pregnant African American women: A randomized controlled trial

BackgroundVaccination coverage with tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine in pregnancy or immediately postpartum has been low. Limited data exist on rigorously evaluated interventions to increase maternal vaccination, including Tdap. Tailored messaging based on the Elaboration Likelihood Model (ELM) framework has been successful in improving uptake of some public health interventions. We evaluated the effect of two ELM-based vaccine educational interventions on Tdap vaccination among pregnant African American women, a group of women who tend to have lower vaccine uptake compared with other groups.MethodsWe conducted a prospective randomized controlled trial to pilot test two interventions – an affective messaging video and a cognitive messaging iBook – among pregnant African American women recruited during routine prenatal care visits. We measured Tdap vaccination during the perinatal period (during pregnancy and immediately postpartum), reasons for non-vaccination, and intention to receive Tdap in the next pregnancy.ResultsAmong the enrolled women (n = 106), 90% completed follow-up. Tdap vaccination in the perinatal period was 18% in the control group; 50% in the iBook group (Risk Ratio [vs. control group]: 2.83; 95% CI, 1.26–6.37), and 29% in the video group (RR: 1.65; 95% CI, 0.66–4.09). From baseline to follow-up, women’s reported intention to receive Tdap during the next pregnancy improved in all three groups. Among unvaccinated women, the most common reason reported for non-vaccination was lack of a recommendation for Tdap by the woman’s physician.ConclusionsEducation interventions that provide targeted information for pregnant women in an interactive manner may be useful to improve Tdap vaccination during the perinatal period. However, larger studies including multiple racial and ethnic groups are needed to evaluate robustness of our findings.Trial Registration: clinicaltrials.gov Identifier: NCT01740310.     

Safety and immunogenicity of seasonal trivalent inactivated influenza vaccines in pregnant women

BackgroundIn the United States, seasonal inactivated influenza vaccine (IIV) is recommended for pregnant women; however, in early 2009, immunization rates were low, partly due to limited prospective data and concerns about vaccine safety.ObjectiveWe conducted a randomized study of two licensed seasonal trivalent IIVs (IIV3) to assess their safety and immunogenicity in pregnant women.Study DesignIn this prospective, randomized clinical study, 100 pregnant women, 18–39 years of age and ≥14 weeks gestation received a single intramuscular dose of 2008–2009 Fluzone® or Fluarix®. Injection site and systemic reactions were recorded for 7 days after vaccination and serious adverse events (SAEs) and pregnancy outcomes were documented. Serum samples collected before and 28 days after vaccination were tested for hemagglutination inhibition (HAI) antibody levels.ResultsThe majority of the injection site and systemic reactions were mild and self-limited after both vaccines. No fever ≥100 °F was reported. There were no vaccine-associated SAEs. Immune responses to influenza vaccine antigens were similar for the two study vaccines, with robust HAI responses against influenza A strains, and relatively lower responses for influenza B strains.ConclusionSeasonal inactivated influenza vaccines were well tolerated and immunogenic in pregnant women.

• ClinicalTrials.gov identifier NCT00905125.

Synopsis: In this prospective clinical trial, we demonstrated that immunization with seasonal trivalent, inactivated influenza vaccine in the second and third trimester of pregnancy is immunogenic and safe.     

A phase 2 randomized controlled dose-ranging trial of recombinant pertussis booster vaccines containing genetically inactivated pertussis toxin in pregnant women

IntroductionDespite a decrease in infections caused by Bordetella pertussis due to COVID-19 pandemic, booster vaccination of pregnant women is still recommended to protect newborns. Highly immunogenic vaccines containing genetically inactivated pertussis toxin (PT_gen) and filamentous hemagglutinin (FHA) may generate comparable anti-PT antibody concentrations, even at lower doses, to chemically inactivated acellular pertussis vaccines (Tdap_chem) shown effective for maternal immunization.MethodsThis phase 2 randomized, observer-blind, active-controlled non-inferiority trial was conducted in healthy Thai pregnant women randomly assigned to receive one dose of low-dose recombinant pertussis-only vaccine containing 1 µg PT_gen and 1 µg FHA (ap1_gen), or tetanus, reduced-dose diphtheria combined with ap1_gen (Tdap1_gen), or combined with 2 µg PT_gen and 5 µg FHA (Tdap2_gen), or with 5 µg PT_gen and 5 µg FHA (TdaP5_gen, Boostagen®) or comparator containing 8 µg of chemically inactivated pertussis toxoid, 8 µg FHA, and 2.5 µg pertactin (Boostrix™, Tdap8_chem). Blood was collected at Day 0 and Day 28 post-vaccination. The non-inferiority of the study vaccines was assessed based on anti-PT IgG antibody levels on Day 28 pooled with results from a similarly structured previous trial in non-pregnant women.Results400 healthy pregnant women received one dose of vaccine. Combined with data from 250 non-pregnant women, all study vaccines containing PT_gen were non-inferior to comparator vaccine (Tdap8_chem). Both ap1_gen and TdaP5_gen vaccines could be considered to have superior immunogenicity to Tdap8_chem. Local and systemic solicited reactions were similar among all vaccine groups.ConclusionsVaccine formulations containing PT_gen were safe and immunogenic in pregnant women. The ap1_gen vaccine, with the lowest cost and reactogenicity, may be suitable for use in pregnant women when diphtheria and tetanus toxoids are not needed.This study is registered in the Thai Clinical Trial Registry (www.clinicaltrials.in.th), number TCTR20180725004.     

Infant pertussis and maternal immunity: The curious case of Canada

BackgroundThe United Kingdom (UK) and Canada use the same acellular pertussis vaccine and both experienced large pertussis outbreaks in the past, occurring in the 1980s in the UK and 1990s in Canada, yet current epidemiology differs. A national outbreak with infant deaths occurred in the UK in 2012, yet outbreaks remain localized and death from pertussis rare in Canada.AimWe explored whether past outbreaks in children may influence future risk when those children become parents.MethodsWe conducted an ecological within-country birth cohort analysis in women of childbearing age of the relative risk of ever having pertussis infection by two points in time, 2002 and 2012, comparing with 1992 as the baseline. We used notified cases of pertussis in England and Wales and Canada to compare trends in relative risk. We projected forward to 2022 in Canada assuming incidence remained stable.ResultsIn Canada, the cumulative risk of previous pertussis was similar in 2002 and 2012 and, in both periods, was higher than in 1992. In England and Wales, the cumulative risk of pertussis fell stepwise from 1992 to 2012. Projecting forwards, the pattern of risk in Canada becomes similar to England and Wales in 2022.ConclusionsWidespread pertussis outbreaks in children may reduce the risk of pertussis in infants when those children become parents. Further research is needed to determine the mechanism. As birth cohorts that experienced outbreaks grow past childbearing age, pertussis burden in infants in Canada may increase, following trends observed in England and Wales.     

Improving influenza and Tdap vaccination during pregnancy: A cluster-randomized trial of a multi-component antenatal vaccine promotion package in late influenza season

BackgroundEvidence-based interventions to improve influenza vaccine coverage among pregnant women are needed, particularly among those who remain unvaccinated late into the influenza season. Improving rates of antenatal tetanus, diphtheria and acellular pertussis (Tdap) vaccination is also needed.PurposeTo test the effectiveness of a practice-, provider-, and patient-focused influenza and Tdap vaccine promotion package on improving antenatal influenza and Tdap vaccination in the obstetric setting.MethodsA cluster-randomized trial among 11 obstetric practices in Georgia was conducted in 2012–2013. Intervention practices adopted the intervention package that included identification of a vaccine champion, provider-to-patient talking points, educational brochures, posters, lapel buttons, and iPads loaded with a patient-centered tutorial. Participants were recruited from December 2012–April 2013 and included 325 unvaccinated pregnant women in Georgia. Random effects regression models were used to evaluate primary and secondary outcomes.ResultsData on antenatal influenza and Tdap vaccine receipt were obtained for 300 (92.3%) and 291 (89.5%) women, respectively. Although antenatal influenza and Tdap vaccination rates were higher in the intervention group than the control group, improvements were not significant (For influenza: risk difference (RD) = 3.6%, 95% confidence interval (CI): −4.0%, 11.2%; for Tdap: RD = 1.3%, 95% CI: −10.7%, 13.2%). While the majority of intervention package components were positively associated with antenatal vaccine receipt, a provider's recommendation was the factor most strongly associated with actual receipt, regardless of study group or vaccine.ConclusionsThe intervention package did not significantly improve antenatal influenza or Tdap vaccine coverage. More research is needed to determine what motivates women remaining unvaccinated against influenza late into the influenza season to get vaccinated. Future research should quantify the extent to which clinical interventions can bolster a provider's recommendation for vaccination. This study is registered with clinicaltrials.gov, study ID NCT01761799.     

Impact of a maternal immunization program against pertussis in a developing country

BackgroundPertussis disease is a growing concern for developing countries. In Argentina, rates of illness and death peaked in 2011. More than 50% of fatalities due to pertussis occurred in infants younger than two months of age, too young for vaccination. In 2012, the government offered immunization with a vaccine containing Tdap to all pregnant women after 20 weeks of gestation with the intent of reducing morbidity and mortality in young infants.MethodsMaternal acellular pertussis vaccine impact on reducing infant disease burden was estimated based on data from the Argentinean Health Surveillance System. We divided Argentinean states in two groups experiencing high (>50) and low (⩽50) Tdap vaccine coverage and compared these two groups using a Bayesian structural time-series model. Low coverage regions were used as a control group, and the time series were compared before and after the implementation of the Tdap program.FindingsWe observed a relative reduction of 51% (95% CI [−67%, −35%]; p = 0.001) in pertussis cases in high coverage states in comparison with the low coverage areas. Analysis of infants between two and six months showed a 44% (95% CI [−66%, −24%]; p = 0.001) reduction in illness. Number of deaths was highest in 2011 with 76 fatalities, for an incidence rate of 2.9 per 100,000. Comparing with 2011, rates decreased by 87% to 10 subjects, or 0.9 per 100,000 in 2013.InterpretationWe show an age-dependent protective effect of maternal Tdap immunization in a developing country for infants younger than six months.     

Cost-effectiveness analysis of universal maternal immunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in Brazil

BackgroundPertussis incidence has increased significantly in Brazil since 2011, despite high coverage of whole-cell pertussis containing vaccines in childhood. Infants <4 months are most affected. This study aimed to evaluate the cost-effectiveness of introducing universal maternal vaccination with tetanus-diphtheria-acellular pertussis vaccine (Tdap) into the National Immunization Program in Brazil.MethodsEconomic evaluation using a decision tree model comparing two strategies: (1) universal vaccination with one dose of Tdap in the third trimester of pregnancy and (2) current practice (no pertussis maternal vaccination), from the perspective of the health system and society. An annual cohort of newborns representing the number of vaccinated pregnant women were followed for one year. Vaccine efficacy were based on literature review. Epidemiological, healthcare resource utilization and cost estimates were based on local data retrieved from Brazilian Health Information Systems. Costs of epidemiological investigation and treatment of contacts of cases were included in the analysis. No discount rate was applied to costs and benefits, as the temporal horizon was one year. Primary outcome was cost per life year saved (LYS). Univariate and best- and worst-case scenarios sensitivity analysis were performed.ResultsMaternal vaccination of one annual cohort, with vaccine effectiveness of 78%, and vaccine cost of USD$12.39 per dose, would avoid 661 cases and 24 infant deaths of pertussis, save 1800 years of life and cost USD$28,942,808 and USD$29,002,947, respectively, from the health system and societal perspective. The universal immunization would result in ICERs of USD$15,608 and USD$15,590 per LYS, from the health system and societal perspective, respectively. In sensitivity analysis, the ICER was most sensitive to discounting of life years saved, variation in case-fatality, disease incidence, vaccine cost, and vaccine effectiveness.ConclusionThe results indicate that universal maternal immunization with Tdap is a cost-effective intervention for preventing pertussis cases and deaths in infants in Brazil.     

Modeling the cost-effectiveness of maternal acellular pertussis immunization (aP) in different socioeconomic settings: A dynamic transmission model of pertussis in three Brazilian states

ObjectivesUsing dynamic transmission models we evaluated the health and cost outcomes of adding acellular pertussis (aP) vaccination of pregnant women to infant vaccination in three Brazilian states that represent different socioeconomic conditions. The primary objective was to determine whether the same model structure could be used to represent pertussis disease dynamics in differing socioeconomic conditions.MethodsWe tested three model structures (SIR, SIRS, SIRSIs) to represent population-level transmission in three socio-demographically distinct Brazilian states: São Paulo, Paraná and Bahia. Two strategies were evaluated: infant wP vaccination alone versus maternal aP immunization plus infant wP vaccination. Model projections for 2014–2029 include outpatient and inpatient pertussis cases, pertussis deaths, years of life lost, disability-adjusted life-years (DALYs) lost, and costs (in 2014 USD) of maternal aP vaccination, infant vaccination, and pertussis medical treatment. Incremental cost per DALY averted is presented from the perspective of the Brazilian National Health System.ResultsBased on goodness-of-fit statistics, the SIRSIs model fit best, although it had only a modest improvement in statistical quantitative assessments relative to the SIRS model. For all three Brazilian states, maternal aP immunization led to higher costs but also saved infant lives and averted DALYs. The 2014 USD cost/DALY averted was $3068 in Sao Paulo, $2962 in Parana, and $2022 in Bahia. These results were robust in sensitivity analyses with the incremental cost-effectiveness ratios exceeding per capita gross regional product only when the probability that a pertussis case is reported was assumed higher than base case implying more overt cases and deaths and therefore more medical costs.ConclusionsThe same model structure fit all three states best, supporting the idea that the disease behaves similarly across different socioeconomic conditions. We also found that immunization of pregnant women with aP is cost-effective in diverse Brazilian states.     

Immunization of pregnant women against pertussis: The effect of timing on antibody avidity

BackgroundThe Centers for Disease Control and Prevention recommend tetanus–diphteria–acellular pertussis (Tdap) immunization during pregnancy, preferably at 27–36 weeks gestation.AimsFirst, to assess the relative avidity index (RAI) of umbilical cord immunoglobulin G (IgG) to pertussis toxin (PT) for newborns of women immunized with Tdap during late pregnancy as compared to unimmunized women. Second, to assess whether there is a preferential period of gestational Tdap immunization that provides the highest RAI of umbilical cord IgG to PT.MethodsRAI of IgG to PT was assessed via an adapted ELISA using NH₄SCN as a dissociating agent.ResultsWe found that newborns of women immunized with Tdap during late pregnancy (n = 52) had higher mean RAI of umbilical cord IgG to PT than those of unimmunized women (n = 8), 73.77% ± 12.08 (95% CI, 70.41–77.13) vs. 50.23% ± 21.32 (95% CI, 32.41–68.06), p < 0.001. Further, the RAI of umbilical cord IgG to PT was significantly higher in newborns of women immunized at 27–30⁺⁶ weeks gestation (n = 20) when compared with newborns of women immunized at 31–36 weeks (n = 22) and >36 weeks (n = 7), 79.53% ± 5.61 (95% CI, 76.91–82.16) vs. 71.56% ± 12.58 (95% CI, 65.98–77.14) vs. 63.93% ± 17.98 (95% CI, 47.31–80.56), p < 0.03.ConclusionGestational Tdap immunization between 27 and 30⁺⁶ weeks resulted in the highest avidity of IgG to PT conveyed at delivery as compared with immunization beyond 31 weeks gestation. Future studies should be conducted to confirm our findings to optimize pertussis-controlling strategies.     

Safety of maternal pertussis vaccination on pregnancy and birth outcomes: A prospective cohort study

ObjectiveTo evaluate the safety of maternal pertussis vaccination on pregnancy and birth outcomes.MethodsThe study population comprised 1272 healthy nulliparous pregnant women who participated in Screening Tests to identify poor Outcomes in Pregnancy (STOP) study at two obstetric hospitals in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination (confirmed by medical records), extensive amounts of pregnancy and birth outcome data collected by research midwives. Adjusted relative risks (aRRs) and hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and the temporal nature of each outcome.ResultsOf the 1272 women included in this study, 80.1% (n = 1019) received maternal pertussis vaccination. Vaccinated women had an average 0.22 weeks (95% CI 0.001, 0.44) longer gestation at delivery compared to unvaccinated women. Maternal pertussis vaccination was not associated with chorioamnionitis (aRR 0.71, 95% CI 0.27,1.82), gestational hypertension (aHR 1.24, 95% CI, 0.66, 2.30), preeclampsia (aHR 0.75, 95% CI 0.47, 1.18) nor preterm birth (aHR 0.99, 95% CI 0.47, 2.07). Neither risk of low birth weight (aHR 0.72, 95% CI 0.41, 1.27) nor small for gestational age infants (aHR 0.67,95% CI 0.29, 1.55) were increased following maternal pertussis vaccination. No associations between pertussis vaccination during pregnancy and adverse birth outcomes including admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for maternal influenza vaccination.ConclusionOur study provides reassuring evidence of the safety of maternal pertussis vaccination with no increased risk of adverse pregnancy and birth outcomes. These findings support recommendations for pertussis vaccination during pregnancy to prevent morbidity and mortality associated with early-infant pertussis disease.     

Influenza vaccine use to protect healthy children: A debated topic

At the beginning of this century, a number of studies suggested that in healthy children, particularly those <2 years of age, influenza could have a serious and complicated course, as it frequently led to hospitalization and sometimes, albeit rarely, to death. Moreover, pre-schoolers and school-age children were found to be among the most important causes of influenza transmission to the community, as they shed the virus for a longer time than adults and had frequent contact with greater numbers of individuals through day-care and school. These findings led a number of health authorities to modify the official recommendations regarding the use of influenza vaccine in healthy children. Several factors seem to indicate that vaccination against influenza in healthy children of any age and in pregnant women could be effective in preventing the disease in the entire paediatric population and in providing herd immunity in adults and old people as well. The direct advantages of the vaccine seem greater in younger subjects, particularly those <2–3 years of age. Vaccination of older children is considered effective by most experts, but high vaccination coverage of these subjects has been difficult to attain. Similar difficulties have been identified for the vaccination of pregnant women. These challenges can be overcome, at least in part, by appropriate information and accurate evaluations of available data. In addition, further studies specifically designed to clarify unresolved problems regarding vaccine use in paediatric and pregnant populations are needed to convince reluctant health authorities. More effective vaccines for younger children as well as improved availability of data regarding the optimal time period for vaccine administration in pregnant women appear relevant in this regard.     

Flu and pertussis vaccination during pregnancy in Geneva during the COVID-19 pandemic: A multicentric,prospective, survey-based study

ObjectiveTo determine pertussis and influenza vaccination coverage during pregnancy among women delivering in all the maternities of Geneva (Switzerland), during the COVID-19 pandemic.MethodsAll women delivering in all the maternity centres of the canton of Geneva from 1st November 2020 to 30th November 2020 (beginning of the flu vaccination season) and from 8th March 2021 to 7th April 2021 (end of the flu vaccination season) had their records checked upon admission to the labour ward regarding pertussis and influenza vaccination during pregnancy. Reasons for non-vaccination were recorded. Univariate and multivariate analyses were done to identify predictors of vaccine uptake.Results951 women delivered in Geneva during the two study periods, of which 950 were included in the study. 86.2% were vaccinated against pertussis, with no significant difference between the study periods (87.5% vs 85% at the beginning and end of the flu vaccination season respectively). 49.8% were vaccinated against influenza, with no significant difference between the study periods (48.8% vs 50.7% beginning and end of the flu vaccination season respectively). The influenza vaccine was 5 times more likely not to be proposed (8.9% vs. 1.7%) and 3 times more likely to be refused (26.6% vs. 8%) than the pertussis vaccine. Main reason for refusal was a lack of maternal desire for both vaccines, but not vaccine fear. Maternal parity ≥ 1 was significantly associated with pertussis vaccine uptake at univariate analysis. Women were significantly more likely to accept the influenza vaccine if they had a university degree or if they did not deliver in a midwife-only run delivery unit in both univariate and multivariate analysis.ConclusionsIn Geneva, most gynaecologists offer pertussis immunization during antenatal care and uptake is high, but more efforts must be done to increase influenza vaccination coverage. Education level impacts maternal flu vaccination uptake, but other social disparities did not.     

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.     

Safety and immunogenicity of three seasonal inactivated influenza vaccines among pregnant women and antibody persistence in their infants

ObjectiveInactivated influenza virus vaccines (IIVs) are recommended for all pregnant women in the United States. We conducted a prospective, randomized, double blind study of three licensed seasonal trivalent IIVs (IIV3s) to assess their safety and immunogenicity in pregnant women and determine the level and persistence of passively transferred maternal antibody in infants.Study design139 pregnant women ages 18–39 years and 14–33 weeks’ gestation, and 44 non-pregnant women, were randomized 1:1:1 to receive a single intramuscular dose of one of three licensed IIV3s (Agriflu®, Fluzone®, or Fluarix®) prior to the 2010–2011 influenza season. Reactogenicity, adverse events (AEs) and pregnancy outcomes were documented. Serum samples for hemagglutination inhibition (HAI) and neutralization antibody assays were collected prior to and 28 and 180 days after immunization. Maternal sera and cord blood were collected at the time of delivery and sera were obtained from 44 infants at 6 weeks of age.ResultsPregnant and non-pregnant women experienced similar frequency of injection site (92% and 86%, respectively) and systemic (95% and 87%, respectively) reactions, the majority of which were mild. There were no vaccine-associated maternal or infant serious AEs. Antibody responses to the three vaccine antigens were not different between pregnant and non-pregnant women. The ratios of cord blood (infant) to maternal HAI antibody titers at delivery ranged between 1.1 and 1.7 for each of the vaccine antigens. Influenza antibody concentrations in infants were 70–40% of the birth titer by 6 weeks of age.ConclusionsThe three IIV3s were well tolerated in pregnant women. Antibody responses were comparable in pregnant and non-pregnant women, and after second or third trimester vaccination. Transplacental transfer of maternal antibodies to the infant was efficient. However, antibody titers decline rapidly in the first 6 weeks of life.     

Identifying ways to increase seasonal influenza vaccine uptake among pregnant women in China: A qualitative investigation of pregnant women and their obstetricians

BackgroundPregnant women are at higher risk for complications from influenza infection. Nevertheless, seasonal influenza vaccination among pregnant women in China is low. A better understanding of perceptions of pregnant women and their physicians, and factors influencing decisions about receiving seasonal influenza vaccine could be used to develop effective strategies for improving seasonal influenza vaccine uptake during pregnancy.MethodsWe recruited pregnant women from 9 hospitals located in 5 cities across China to participate in focus group interviews. Obstetricians from the same hospitals were recruited for one on one in-depth interviews. We collected information about perceptions of barriers and motivating factors for utilizing seasonal influenza vaccine during pregnancy. We systematically analyzed the information using qualitative methods.ResultsWe conducted 18 focus groups with 108 pregnant women and interviewed 18 obstetricians. Awareness about the use of influenza vaccine during pregnancy was minimal in both subject groups. None of the pregnant women had received influenza vaccine during pregnancy and none of the obstetricians had recommended influenza vaccine for their patients. Both groups noted insufficient knowledge about influenza infection and benefits of the vaccine, concerns about vaccine safety, and lack of local data related to vaccine use in Chinese pregnant women. Obstetricians cited the lack of a national policy as a major barrier to recommending seasonal influenza vaccine to pregnant women. Pregnant women cited not receiving a recommendation for vaccination from healthcare workers as an additional barrier.ConclusionOur findings highlight the immediate need to increase awareness and knowledge about the risks of influenza infection and the benefits and safety of seasonal influenza vaccination among both pregnant women and obstetricians in China. Obstetricians interviewed stated that the development and implementation of a national policy prioritizing pregnant women for seasonal influenza vaccination would facilitate their willingness to recommend seasonal influenza vaccine to pregnant women.     

Implementation of maternal influenza immunization in El Salvador: Experiences and lessons learned from a mixed-methods study

IntroductionThe World Health Organization (WHO) recommends that countries prioritize pregnant women for influenza vaccination, yet few low- or middle-income countries (LMICs) have implemented maternal influenza immunization programs. To inform vaccine decision-making and operational planning in LMICs, there is a need to document and share experiences from countries that provide seasonal influenza vaccine to pregnant women, particularly those with high coverage, like El Salvador.MethodsIn 2015 and 2016, PATH and country researchers conducted a mixed-methods study to document the experience and lessons learned from maternal influenza immunization delivery and acceptance in El Salvador as part of a collaborative effort between WHO and PATH. Researchers conducted focus group discussions, semi-structured interviews, antenatal clinic exit interviews, and key informant interviews with 326 participants from two municipalities in each of the country’s three regions. Respondents included pregnant and recently pregnant women, family members, community leaders, health personnel, public health managers and partners, and policymakers.ResultsFactors perceived as positively influencing maternal influenza immunization delivery and acceptance in El Salvador include the use of multiple vaccine delivery strategies, targeted education and community engagement efforts, and a high degree of trust between the community and health care providers. Influenza vaccine acceptance by pregnant women is high and has improved over time, largely attributed to education targeting health care advisors. Perceived challenges to pregnant women receiving health care and vaccination include the need for permission to attend services and limited access to health services in insecure areas related to the presence of criminal gang activity.ConclusionsWe identified approaches and barriers perceived to affect maternal influenza vaccine delivery in El Salvador. This information will be useful to public health decision-makers and implementers in El Salvador and other countries considering introduction of new maternal vaccines or striving to increase coverage of vaccines currently provided.