Vaccinating pregnant women against influenza needs to be a priority for all countries: An expert commentary

Pathogenesis of viral infections during pregnancy

SUMMARYViral infections during pregnancy are associated with significant adverse perinatal and fetal outcomes. Pregnancy is a unique immunologic and physiologic state, which can influence control of virus replication, severity of disease, and vertical transmission. The placenta is the organ of the maternal-fetal interface and provides defense against microbial infection while supporting the semi-allogeneic fetus via tolerogenic immune responses. Some viruses, such as cytomegalovirus, Zika virus, and rubella virus, can breach these defenses, directly infecting the fetus and having long-lasting consequences. Even without direct placental infection, other viruses, including respiratory viruses like influenza viruses and severe acute respiratory syndrome coronavirus 2, still cause placental damage and inflammation. Concentrations of progesterone and estrogens rise during pregnancy and contribute to immunological adaptations, placentation, and placental development and play a pivotal role in creating a tolerogenic environment at the maternal-fetal interface. Animal models, including mice, nonhuman primates, rabbits, and guinea pigs, are instrumental for mechanistic insights into the pathogenesis of viral infections during pregnancy and identification of targetable treatments to improve health outcomes of pregnant individuals and offspring.

RSV Prefusion F Protein-Based Maternal Vaccine - Preterm Birth and Other Outcomes

BACKGROUND

Vaccination against respiratory syncytial virus (RSV) during pregnancy may protect infants from RSV disease. Efficacy and safety data on a candidate RSV prefusion F protein-based maternal vaccine (RSVPreF3-Mat) are needed.

METHODS

We conducted a phase 3 trial involving pregnant women 18 to 49 years of age to assess the efficacy and safety of RSVPreF3-Mat. The women were randomly assigned in a 2:1 ratio to receive RSVPreF3-Mat or placebo between 24 weeks 0 days and 34 weeks 0 days of gestation. The primary outcomes were any or severe medically assessed RSV-associated lower respiratory tract disease in infants from birth to 6 months of age and safety in infants from birth to 12 months of age. After the observation of a higher risk of preterm birth in the vaccine group than in the placebo group, enrollment and vaccination were stopped early, and exploratory analyses of the safety signal of preterm birth were performed.

RESULTS

The analyses included 5328 pregnant women and 5233 infants; the target enrollment of approximately 10,000 pregnant women and their infants was not reached because enrollment was stopped early. A total of 3426 infants in the vaccine group and 1711 infants in the placebo group were followed from birth to 6 months of age; 16 and 24 infants, respectively, had any medically assessed RSV-associated lower respiratory tract disease (vaccine efficacy, 65.5%; 95% credible interval, 37.5 to 82.0), and 8 and 14, respectively, had severe medically assessed RSV-associated lower respiratory tract disease (vaccine efficacy, 69.0%; 95% credible interval, 33.0 to 87.6). Preterm birth occurred in 6.8% of the infants (237 of 3494) in the vaccine group and in 4.9% of those (86 of 1739) in the placebo group (relative risk, 1.37; 95% confidence interval [CI], 1.08 to 1.74; P = 0.01); neonatal death occurred in 0.4% (13 of 3494) and 0.2% (3 of 1739), respectively (relative risk, 2.16; 95% CI, 0.62 to 7.56; P = 0.23), an imbalance probably attributable to the greater percentage of preterm births in the vaccine group. No other safety signal was observed.

CONCLUSIONS

The results of this trial, in which enrollment was stopped early because of safety concerns, suggest that the risks of any and severe medically assessed RSV-associated lower respiratory tract disease among infants were lower with the candidate maternal RSV vaccine than with placebo but that the risk of preterm birth was higher with the candidate vaccine. (Funded by GlaxoSmithKline Biologicals; ClinicalTrials.gov number, NCT04605159.).

Midwives' experiences of discussing health behaviour change within routine maternity care: A qualitative systematic review and meta-synthesis

PROBLEM

Behaviours, such as smoking, alcohol use, unhealthy diet, lack of physical activity and vaccination non-adherence may lead to adverse pregnancy outcomes.

BACKGROUND

Pregnancy has been identified as an opportune time for midwives to support women to make health behaviour changes.

AIM

To synthesise existing qualitative research exploring midwives' experiences of discussing health behaviour change with women within routine care.

METHODS

A systematic search was conducted across: Maternity and Infant Care, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, and Applied Social Sciences Index and Abstracts. Thematic analysis was used to synthesise the data. A professional and public advisory group provided feedback during the synthesis stage.

FINDINGS

Twenty-two studies, published between 2005 and 2023, which represented findings from eight countries, were included in the review. The meta-synthesis revealed three themes: The midwife-woman relationship; Reflective and tailored behaviour change communication; Practical barriers to behaviour change conversations. This led to one overarching theme: Although midwives recognised the importance of behaviour change discussions, these conversations were not prioritised in clinical practice.

CONCLUSION

Health behaviour change discussions were de-prioritised in midwives' clinical practice. Future research should explore intervention development to support midwives with their health behaviour change communication.

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

BACKGROUND

Maternal 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).

OBJECTIVES

The purpose of this article was to summarize evidence from published literature on the effect of key interventions targeting maternal infections on adverse birth outcomes.

METHODS

We 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.

RESULTS

Of 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.

CONCLUSIONS

At present, there is limited evidence from RCTs available for some potentially relevant interventions targeting maternal infections, which could be prioritized for future research.

Vaccination against influenza in pregnant women in a maternity hospital in the Czech Republic in the season 2020-2021

OBJECTIVES

Pregnant women are among the priority groups to receive influenza vaccines in the Czech Republic since 2011, data on vaccination coverage are not yet available. The aim of the study was to determine the influenza vaccination coverage (IVC) and provide source data for further activities.

METHODS

A prospective observational study was performed in a large maternity hospital in Prague. The self-completed questionnaire was distributed to 5,475 pregnant women between September 1, 2020 and August 31, 2021. Questions included maternal sociodemographic characteristics, influenza vaccination status and sources of maternal vaccination recommendations during pregnancy.

RESULTS

A total of 4,617 completed questionnaires have been analysed. The median age of study participants (N = 4,592) was 33 years (range: 18-51 years). The majority (69.7%) of women had completed their university education, most women were childless (58.5%) or had one child (32.5%) before the start of the study. Less than 2% of women reported being vaccinated against influenza during their pregnancy (1.5%; 95% CI, 1.1-1.9%). Only 21% of women knew that it's possible to get vaccinated against influenza during pregnancy. Participants considered influenza vaccination in pregnancy as important (3.3%), useful (41.1%) and useless (44.4%). Out of 959 pregnant women who had information about influenza vaccination during pregnancy, only 6.9% were vaccinated, while among those who did not have this information, 0.1% were vaccinated during pregnancy (p < 0.001). The most frequent source of information was Internet, then media and a general practitioner.

CONCLUSIONS

The IVC during pregnancy in our study was extremely low. In order to improve IVC among pregnant women, it is necessary to increase awareness of recommendations and vaccination options among the public and professionals and incorporating vaccination recommendation in routine antenatal practice.

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

OBJECTIVE

Influenza vaccination during pregnancy is highly recommended. We examined the association between maternal influenza vaccination and adverse birth outcomes.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Our findings suggest that influenza vaccination during pregnancy is a safe and effective way to protect newborns.

Biological Sex and Pregnancy Affect Influenza Pathogenesis and Vaccination

Males and females differ in the outcome of influenza A virus (IAV) infections, which depends significantly on age. During seasonal influenza epidemics, young children (< 5 years of age) and aged adults (65+ years of age) are at greatest risk for severe disease, and among these age groups, males tend to suffer a worse outcome from IAV infection than females. Following infection with pandemic strains of IAVs, females of reproductive ages (i.e., 15-49 years of age) experience a worse outcome than their male counterparts. Although females of reproductive ages experience worse outcomes from IAV infection, females typically have greater immune responses to influenza vaccination as compared with males. Among females of reproductive ages, pregnancy is one factor linked to an increased risk of severe outcome of influenza. Small animal models of influenza virus infection and vaccination illustrate that immune responses and repair of damaged tissue following IAV infection also differ between the sexes and impact the outcome of infection. There is growing evidence that sex steroid hormones, including estrogens, progesterone, and testosterone, directly impact immune responses during IAV infection and vaccination. Greater consideration of the combined effects of sex and age as biological variables in epidemiological, clinical, and animal studies of influenza pathogenesis is needed.

Best practices in prenatal health promotion: Perceptions, experiences, and recommendations of Ottawa, Canada, prenatal key informants

BACKGROUND

Prenatal health promotion includes the provision of evidence-based information and practical skills to optimize maternal-fetal outcomes. Increasingly, prenatal education is delivered by both healthcare professionals and allied childbirth educators, in community- or hospital-based group classes, targeted outreach programs, and online modules.

OBJECTIVES

To better understand how prenatal health promotion relates to a diverse urban community, we assessed the perspectives of Ottawa, Canada prenatal key informants.

DESIGN

This is a qualitative research with key informant interviews.

METHODS

Semi-structured interviews were conducted with 11 prenatal key informants, responsible for the design, delivery, or promotion of publicly available prenatal health services. Interviews explored concepts and delivery of prenatal health promotion, strategies to address existing and emerging prenatal topics, identification of barriers to prenatal health services, and recommendations.

RESULTS

Key informants recommended a lifespan approach to prenatal health promotion, with an emphasis on healthy behaviors, emotional health, labor and delivery, and postpartum/early parenting. Recognizing community health disparities, key informants used community outreach, and intersectoral collaborations for Indigenous and other at-risk communities to mitigate barriers to prenatal service uptake.

CONCLUSIONS

Ottawa key informants conceptualized prenatal health promotion as inclusive, comprehensive, and as an extension of preconception, school-based sexual education. Respondents recommended the design and delivery of prenatal interventions as culturally safe and trauma informed, using online modalities to complement in-person activities. The experience and intersectoral networks of community-based prenatal health promotion programs represent potential capacity to address emergent public health risks to pregnancy, particularly among at-risk populations.

PLAIN LANGUAGE SUMMARY

A broad and diverse community of professionals deliver prenatal education to help people have healthy babies. We interviewed Ottawa, Canada experts in prenatal care/education to learn about the design and delivery of reproductive health promotion. We found that Ottawa experts emphasized healthy behaviors beginning before conception and through pregnancy. Community outreach was identified as a successful strategy to promote prenatal education to marginalized groups.

Nonrespiratory sites of influenza-associated disease: mechanisms and experimental systems for continued study

The productive replication of human influenza viruses is almost exclusively restricted to cells in the respiratory tract. However, a key aspect of the host response to viral infection is the production of inflammatory cytokines and chemokines that are not similarly tissue restricted. As such, circulating inflammatory mediators, as well as the resulting activated immune cells, can induce damage throughout the body, particularly in individuals with underlying conditions. As a result, more holistic experimental approaches are required to fully understand the pathogenesis and scope of influenza virus-induced disease. This review summarizes what is known about some of the most well-appreciated nonrespiratory tract sites of influenza virus-induced disease, including neurological, cardiovascular, gastrointestinal, muscular and fetal developmental phenotypes. In the context of this discussion, we describe the in vivo experimental systems currently being used to study nonrespiratory symptoms. Finally, we highlight important future questions and potential models that can be used for a more complete understanding of influenza virus-induced disease.

RSV disease in infants and young children: Can we see a brighter future?

Respiratory syncytial virus (RSV) is a highly contagious seasonal virus and the leading cause of Lower Respiratory Tract Infections (LRTI), including pneumonia and bronchiolitis in children. RSV-related LRTI cause approximately 3 million hospitalizations and 120,000 deaths annually among children <5 years of age. The majority of the burden of RSV occurs in previously healthy infants. Only a monoclonal antibody (mAb) has been approved against RSV infections in a restricted group, leaving an urgent unmet need for a large number of children potentially benefiting from preventive measures. Approaches under development include maternal vaccines to protect newborns, extended half-life monoclonal antibodies to provide rapid long-lasting protection, and pediatric vaccines. RSV has been identified as a major global priority but a solution to tackle this unmet need for all children has yet to be implemented. New technologies represent the avenue for effectively addressing the leading-cause of hospitalization in children <1 years old.

Respiratory Syncytial Virus in Pregnant Women: Systematic Review and Meta-Analysis

Human Respiratory Syncytial Virus (RSV) is a highly contagious viral pathogen. In infants, it is usually listed among the main causes of medical referrals and hospitalizations, particularly among newborns. While waiting for the results of early randomized controlled trials on maternal vaccination against RSV, the present systematic review and meta-analysis aimed to collect available evidence on maternal RSV infections. According to the PRISMA statement, Pubmed, Embase, and pre-print archive medRxiv.og were searched for eligible studies published up to 1 April 2022. Raw data included the incidence of RSV infection among sampled pregnant women, and the occurrence of complications. Data were then pooled in a random-effects model. Heterogeneity was assessed using the I2 measure, while reporting bias was assessed by means of funnel plots and regression analysis. A total of 5 studies for 282,918 pregnancies were retrieved, with a pooled prevalence of 0.2 per 100 pregnancies and 2.5 per 100 pregnancies with respiratory tract infections. Neither maternal deaths nor miscarriages were reported. Even though detailed data were available only for 6309 pregnancies and 33 RSV cases, infant outcomes such as low birth weight and preterm delivery were rare (in both cases 0.04%), but up to 9.1% in cases where RSV diagnosis was confirmed. No substantially increased risk for preterm delivery (RR 1.395; 95%CI 0.566 to 3.434) and giving birth to a low-birth-weight infant (RR 0.509; 95%CI 0.134 to 1.924) was eventually identified. Conclusions. Although RSV is uncommonly detected among pregnant women, incident cases were associated with a relatively high share of complications. However, heterogeneous design and the quality of retrieved reports stress the need for specifically designed studies.

Knowledge attitudes and practices toward seasonal influenza vaccine among pregnant women during the 2018/2019 influenza season in Tunisia

Background

The uptake and acceptance of the influenza vaccine (IV) among pregnant women remain unknown in Tunisia despite the increased influenza-related complications and death. The present study aimed to assess the IV uptake and acceptability and to describe related knowledge and attitudes among pregnant women in Tunisia.

Methods

A cross-sectional study was conducted in 84 Tunisian healthcare facilities over a period of three months (from March to May 2019). All pregnant women aged ≥18 years who sought antenatal care in related health structures were included in this study based on a multistage self-weighted sampling. We measured knowledge and attitudes towards the IV and assessed factors related to willingness for its uptake.

Results

The questionnaire was completed by 1157 pregnant women. More than half of the participants (60.2%; 95% confidence interval [CI] [57.3%–63.0%]) reported awareness about the IV. Among included PW, only 4.6%; 95% CI [3.5%–6.1%] received it during their current pregnancy. However, (36.8%; 95% CI [34.0%–39.6%]) declared their willingness to receive the vaccine in the next pregnancy. Recommendation by healthcare providers, identified to be the most trustful source of information, was the main reason for acceptance. However, the intention to accept the IV by pregnant women was significantly associated with such recommendation and perceived safety and effectiveness of this vaccine.

Conclusion

Antenatal care visits are a precious opportunity that should not be missed by health care providers and especially gynecologists to promote the IV uptake by pregnant women in Tunisia.

Maternal vaccination: a review of current evidence and recommendations

Maternal vaccination is an effective means of protecting pregnant women, their fetuses, and infants from vaccine-preventable infections. Despite the availability of sufficient safety data to support the use of vaccines during pregnancy, maternal immunization remains an underutilized method of disease prevention, often because of concerns from both healthcare providers and pregnant women about vaccine safety. Such concerns have been reflected in the low uptake of the COVID-19 vaccine among pregnant women seen in many parts of the world. Here, we present an update of the current recommendations for the use of vaccines during pregnancy, including the evidence supporting the use of novel vaccine platforms. We also provide an overview of the data supporting the use of COVID-19 vaccines in pregnancy and an update of the status of vaccines that are currently under development for use in pregnant women.

Knowledge, Attitude, Perceptions, and Concerns of Pregnant Women Regarding the Influenza Vaccination in Kocaeli, Turkey

Introduction In order to better understand the barriers to influenza vaccination, we have designed a study to investigate pregnant women's knowledge, attitude, perceptions, and concerns towards the inactivated influenza vaccine. Materials and methods In this prospective study, carried out between July 1, 2019, and December 31, 2019, 252 pregnant women (≥12 weeks of gestational age), who had consented to be enrolled in the study, were asked to complete an interviewer-administered questionnaire during their stay in the hospital ward. Results The lack of information about influenza vaccines (59.4%) was in the first rank among the reasons for personal and parental vaccine rejection. Most (65.1%) pregnant women either did not believe in or had doubts about the efficiency of the influenza vaccine during gestation. Most of them (80.9%) either were not sure about or did not have much confidence in the prenatally inoculated vaccine's ability to protect their babies postnatally. Some (25.6%) participants attributed their vaccinal unwillingness to fear of adverse effects, and some (11.5%) deemed gestational influenza immunization unnecessary because of their tendency to underestimate the grave consequences of influenza contracted by infants within the first six months of life. The higher the education level, the higher was the knowledge of and the willingness to be immunized against influenza. Discussion It is known that about one-third of pregnant women in Turkey have never heard of the influenza vaccine. Unawareness of influenza vaccination in pregnancy is significantly related to vaccine uptake in Japan. Patient education on knowledge of influenza and influenza vaccination has a booster effect on vaccination rates. Had the influenza vaccine been routinely administered to pregnant women in Turkey, the lives of the majority of the women who died of influenza in the influenza A (H1N1) pandemic in 2009 would have been saved. Low-risk perception is quoted as one of the main reasons for influenza vaccine refusal during pregnancy, which was also the case in our study. Concordant with the current literature, the education level and household income were correlated with the level of influenza vaccination uptake. Pregnant women's fear of adverse effects of the influenza vaccine might extend to the fear of birth defects. Conclusion The acceptance of influenza vaccines by pregnant women is a consequence of complex interactions of various factors. Giving necessary information to pregnant women is one of the most important factors that can increase influenza vaccine uptake. For this reason, it should be ensured that the efficacy and safety data of the influenza vaccine are more widely included in vocational training activities of health personnel and in prenatal care textbooks and guidelines.

Views and experiences of maternal healthcare providers regarding influenza vaccine during pregnancy globally: A systematic review and qualitative evidence synthesis

BACKGROUND

The World Health Organization (WHO) recommends that pregnant women receive influenza vaccination; however, uptake of the vaccine remains low. Maternity health care professionals (MHCPs) play an important role in motivating pregnant women to receive the influenza vaccine. However, factors such as MHCPs' views and knowledge about the vaccine, and time constraints due to workload may influence MHCPs' practices and opinions about women receiving the influenza vaccine during pregnancy. To date, the qualitative evidence exploring MHCPs' views and experiences around influenza vaccine uptake in pregnant women has not been synthesised.

AIM

To systematically review and thematically synthesise qualitative evidence that explores the views and experiences of MHCPs involved in the provision of the maternal influenza vaccine worldwide.

METHODS

Five databases (MEDLINE, EMBASE, PsycINFO, CINAHL, Web of Science) were searched, supplemented with searches of included paper reference lists and grey literature. Study selection was conducted by up to three researchers applying pre-specified inclusion/exclusion criteria. Quality assessment was undertaken, data were extracted, coded and synthesised to develop descriptive and analytical themes.

RESULTS

Eight studies involving 277 participants were included. Seventeen descriptive themes were interpreted, embedded within six analytical themes. MHCPs perceived that maternal influenza vaccination delivery can be facilitated by trusting relationships, good communication, knowledge about the vaccine leading to confidence in recommending vaccine, electronic vaccination prompts, and presence of national guidelines. However, workload, time constraints, MHCP's perception of pregnant women's concerns, and social/cultural/environmental influences could prevent the likelihood of delivery of influenza vaccine. Knowledgeable MHCPs who were regularly updated about vaccination based on scientific evidence were more confident when discussing and recommending the influenza vaccine to pregnant women. In addition, the presence of national policies and guidelines and electronic prompts for maternal influenza vaccination would enhance the delivery of the vaccine.

CONCLUSION

Our findings suggest that approaches to enhance the vaccination uptake rate in pregnant women include addressing MHCPs barriers to discussing influenza vaccination through education, sufficient time for discussions, and electronic prompts about vaccination, as well as evidence based local and national guidelines.

Determinants of maternal influenza vaccination in the context of low- and middle-income countries: A systematic review

BACKGROUND

Pregnancy and early infancy are considered to be the vulnerable phases for severe influenza infection causing morbidity and mortality. Despite WHO recommendations, influenza is not included in the immunization programs of many low- and middle-income countries. This systematic review is aimed at identifying barriers and facilitators for maternal influenza vaccination amongst the perinatal women and their health care providers in low- and middle-income countries.

METHODS

We selected 11 studies from the 1669 records identified from PubMed, CABI, EMBASE and Global Health databases. Studies related to both pandemic and routine influenza vaccination and studies conducted amongst women in the antenatal as well as postnatal period were included. Both qualitative, quantitative, cross-sectional and interventional studies were included.

RESULTS

Knowledge about influenza disease, perception of the disease severity during pregnancy and risk to the foetus/newborn and perceived benefits of influenza vaccination during pregnancy were associated with increased uptake of influenza vaccination during pregnancy. Recommendation by health care provider, vaccination in previous pregnancy and availability of vaccine in public health system facilitated vaccine uptake. High parity, higher education, vaccination in the later months of pregnancy, less than 4 antenatal visits, concerns about vaccine safety and negative publicity in media were identified as barriers for influenza vaccination. Lack of government recommendation, concerns about safety and effectiveness and distrust in manufacturer were the barriers for the healthcare providers to recommend vaccination.

CONCLUSION

While availability of influenza vaccine in public health system can be a key to the success of vaccine implementation program, increasing the awareness about need and benefits of maternal influenza vaccination amongst pregnant women as well as their health care providers is crucial to improve the acceptance of maternal influenza vaccination in low and middle-income countries.

Exposure to quadrivalent influenza vaccine during pregnancy: Results from a global pregnancy registry

BACKGROUND

The Fluzone® Quadrivalent (IIV4, Sanofi Pasteur) Pregnancy Registry was created to monitor vaccine safety during pregnancy (clinicaltrials.gov, NCT01945424). Here, we describe maternal, pregnancy, obstetrical and neonatal outcomes after vaccine exposure in pregnant women between August 2013 and September 2019.

METHODS

All women exposed to IIV4 during their pregnancy were eligible for inclusion. Outcomes were prospective (reported following vaccine exposure but before knowledge of pregnancy outcome ascertained through prenatal tests) or retrospective (prenatal tests were undertaken before the exposure was reported).

RESULTS

Among 239 IIV4 vaccine exposure reports received, there were 105 prospective and 10 retrospective reports of maternal adverse events (AEs). The most frequent prospectively reported maternal AEs were medication errors (expired product [n = 8, 3.8%]; extra dose [n = 7, 3.3%]) and injection site pain (n = 7, 3.3%). Among 62 prospectively reported pregnancy and obstetrical events with available follow-up information, seven AEs were reported, four (6.4%) of which were spontaneous abortions. A further seven AEs were reported among the 29 retrospective pregnancy and obstetrical events with available follow-up information. Among neonatal outcomes (15 prospective; 28 retrospective), >85% were reported as full-term births. One premature birth was reported prospectively. Four other neonatal AEs were reported, all retrospectively: two cases of talipes (club foot), one central nervous system anomaly and one atrial septal defect. All infants with available information had normal APGAR scores at 5 minutes.

CONCLUSIONS

The frequency of AEs following exposure to IIV4 during pregnancy did not indicate new safety concerns.

Vaccination in pregnancy against pertussis and seasonal influenza: key learnings and components from high-performing vaccine programmes in three countries: the United Kingdom, the United States and Spain

BACKGROUND

Pertussis and seasonal influenza are responsible for significant maternal, neonatal, and infant morbidity and mortality, but vaccine coverage rates (VCR) for both pertussis (administered as a tetanus, diphtheria, acellular pertussis [Tdap] vaccination) and seasonal influenza in pregnancy remain generally low. Only a small number of countries, including Spain, the United Kingdom (UK), and the United States (US), have high Tdap and seasonal influenza VCRs in pregnancy. The purpose of this study was to identify the key factors that contributed to the high VCRs observed in these countries.

METHODS

The experience from both Tdap and seasonal influenza vaccination programmes during pregnancy were documented in Spain, the UK, and the US using a three-step approach. A literature review yielded 157 publications, and a further 117 documents were selected through desk research. A published five-pillar VCR framework for influenza was amended to evaluate the specific contributing factors leading to high Tdap and seasonal influenza VCRs among pregnant women.

RESULTS

The analysis identified components that contributed to higher VCR in pregnant women across three different healthcare systems in Spain, UK, and US. The combination of several key interventions in each country led to a rapid increase in VCR that reached near-optimal levels (i.e. 75% for seasonal influenza) within a few years. As well as inclusion in national immunisation programme and vaccine reimbursement, key components that were identified included the mobilisation of health authorities, prenatal care Healthcare Professionals (HCP) and scientific societies, the inclusion of vaccination in antenatal medical guidance, the provision of educational material to HCPs, and a strong disease awareness driven by recent pertussis outbreaks in each country.

CONCLUSIONS

Although there is no simple, universal solution to improving sub-optimal VCRs, the list of components identified in this study from three countries with high-performing Tdap and seasonal influenza vaccination programmes provides a basis for public health and medical stakeholders in other countries to define strategies to successfully implement national vaccination programmes for pregnant women.

Acceptance of seasonal influenza vaccination and associated factors among pregnant women in the context of COVID-19 pandemic in China: a multi-center cross-sectional study based on health belief model

Background

Seasonal influenza can circulate in parallel with coronavirus disease (COVID-19) in winter. In the context of COVID-19 pandemic, the risk of co-infection and the burden it poses on healthcare system calls for timely influenza vaccination among pregnant women, who are the priority population recommended for vaccination. We aimed to evaluate the acceptance of influenza vaccination and associated factors among pregnant women during COVID-19 pandemic, provide evidence to improve influenza vaccination among pregnant women, help reduce the risk of infection and alleviate the burden of healthcare system for co-infected patients.

Methods

We conducted a multi-center cross-sectional study among pregnant women in China. Sociodemographic characteristics, health status, knowledge on influenza, attitude towards vaccination, and health beliefs were collected. Locally weighted scatterplot smoothing regression analysis was used to evaluate the trends in the acceptance of influenza vaccine. Logistic regression was applied to identify factors associated with vaccination acceptance.

Results

The total acceptance rate was 76.5% (95%CI: 74.8–78.1%) among 2568 pregnant women enrolled. Only 8.3% of the participants had a history of seasonal influenza vaccination. In the logistic regression model, factors associated with the acceptance of influenza vaccine were western region, history of influenza vaccination, high knowledge of influenza infection and vaccination, high level of perceived susceptibility, perceived benefit, cues to action and low level of perceived barriers. Among 23.5% of the participants who had vaccine hesitancy, 48.0% of them were worried about side effect, 35.6% of them lacked confidence of vaccine safety.

Conclusions

Our findings highlighted that tailored strategies and publicity for influenza vaccination in the context of COVID-19 pandemic are warranted to reduce pregnant women’s concerns, improve their knowledge, expand vaccine uptake and alleviate pressure for healthcare system.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04224-3.

Maternal immunization: trends in South and Southeast Asian countries

Maternal immunization has the potential to reduce neonatal deaths caused by vaccine-preventable infectious diseases. Elimination of maternal and neonatal tetanus from many countries illustrates the potential benefits of maternal immunization as a strategy to decrease neonatal mortality caused by vaccine-preventable infections. Many countries in South and Southeast Asia have high cases of neonatal deaths, which were historically attributed to vaccine-preventable infections. Still, these countries vary in recommendations regarding immunization of pregnant women. We reviewed the current recommendations for the use of tetanus toxoid, tetanus-diphtheria, or tetanus-diphtheria-acellular pertussis (Tdap) vaccines for immunization of pregnant women. In addition to protection against tetanus and diphtheria, administration of the Tdap vaccine to pregnant women could help protect neonates against pertussis until they can receive the first two vaccine doses of their primary course. Vaccination against seasonal influenza is also recommended in many countries worldwide for pregnant women as influenza can pose health risks for the mother-fetus unit and the infant. Despite the recognized benefit of influenza vaccination for pregnant women, only some South and Southeast Asian countries have implemented its recommendation. The success of maternal tetanus vaccination has kindled the interest in vaccines that can be safely administered during pregnancy. Future availability of vaccines against respiratory syncytial virus and group B streptococcus, for use in pregnant women, could help prevent neonatal infections, especially in regions where diseases are less controlled. Communicating the body of evidence that supports maternal immunization to obstetricians is key for achieving optimal vaccination coverage to ensure protection of neonates. The current review aims to create awareness about the existing and potential benefits of maternal immunization in South and Southeast Asia.

Pregnant women voice their concerns and birth expectations during the COVID-19 pandemic in Italy

BACKGROUND

In March 2020, COVID-19 was declared to be a pandemic. While data suggests that COVID-19 is not associated with significant adverse health outcomes for pregnant women and newborns, the psychological impact on pregnant women is likely to be high.

AIM

The aim was to explore the psychological impact of the COVID-19 pandemic on Italian pregnant women, especially regarding concerns and birth expectations.

METHODS

A cross-sectional online survey of pregnant women in Italy was conducted. Responses were analysed for all women and segregated into two groups depending on previous experience of pregnancy loss. Analysis of open text responses examined expectations and concerns before and after the onset of the pandemic.

FINDINGS

Two hundred pregnant women responded to the first wave of the survey. Most (n=157, 78.5%) had other children and 100 (50.0%) had a previous history of perinatal loss. 'Joy' was the most prevalent emotion expressed before COVID-19 (126, 63.0% before vs 34, 17.0% after; p<0.05); fear was the most prevalent after (15, 7.5% before vs 98, 49.0% after; p<0.05). Positive constructs were prevalent before COVID-19, while negative ones were dominant after (p<0.05). Across the country, women were concerned about COVID-19 and a history of psychological disorders was significantly associated with higher concerns (p<0.05). A previous pregnancy loss did not influence women's concerns.

CONCLUSIONS

Women's expectations and concerns regarding childbirth changed significantly as a result of the COVID-19 pandemic in Italy. Women with a history of psychological disorders need particular attention as they seem to experience higher levels of concern.

Antibody responses induced by trivalent inactivated influenza vaccine among pregnant and non-pregnant women in Thailand: A matched cohort study

BACKGROUND

We compared influenza antibody titers among vaccinated and unvaccinated pregnant and non-pregnant women.

METHODS

During 1st June- 30th September 2018, four groups of cohort participants-vaccinated pregnant, unvaccinated pregnant, vaccinated non-pregnant, and unvaccinated non-pregnant women were selected by matching age, gestational age, and the week of vaccination. Serum antibody titers against each strain of 2018 Southern Hemisphere inactivated trivalent influenza vaccine (IIV3) were assessed by hemagglutination inhibition (HI) assay on Day 0 (pre-vaccination) and Day 28 (one month post-vaccination) serum samples. Geometric mean titer (GMT), GMT ratio (GMR), seroconversion (defined as ≥4 fold increase in HI titer), and seroprotection (i.e. HI titer ≥1:40) were compared across the study groups using multilevel regression analyses, controlling for previous year vaccination from medical records and baseline antibody levels.

RESULTS

A total of 132 participants were enrolled in the study (33 in each of the four study groups). The baseline GMTs for influenza A(H1N1), A(H3N2), and B vaccine strains were not significantly different among all four groups (all p-values >0.05). After one month, both vaccinated groups had significantly higher GMT, GMR, seroconversion, and seroprotection than their unvaccinated controls (all p-values <0.05). The seroconversion rate was over 60% for any strain among the vaccinated groups, with the highest (88.8%) observed against A(H1N1) in the vaccinated pregnant group. Similarly, at least 75% of the vaccinated participants developed seroprotective antibody levels against all three strains; the highest seroprotection was found against A(H3N2) at 92.6% among vaccinated non-pregnant participants. Antibody responses (post-vaccination GMT, GMR, seroconversion, and seroprotection) were not significantly different between pregnant and non-pregnant women for all three strains of IIV3 (all p>0.05).

CONCLUSIONS

The 2018 seasonal IIV3 was immunogenic against all three vaccine strains and pregnancy did not seem to alter the immune response to IIV3. These findings support the current influenza vaccination recommendations for pregnant women.

Seasonal influenza vaccine exposure in pregnancy: 5-year results from a pregnancy registry

The World Health Organization recommends that all pregnant women receive seasonal influenza vaccine. Under a post-authorization safety study protocol (NCT02148211), a pregnancy exposure registry was established in the United States to monitor spontaneously reported pregnancy outcomes in women vaccinated with GSK’s seasonal inactivated influenza vaccines (IIVs). From 1 June 2014 to 31 May 2019, 507 pregnancies were prospectively reported: 352 (69.4%) were lost to follow-up and 40 (7.9%) were ongoing. Reported outcomes for the remaining 115 were: 101 (87.8%) live births without congenital anomalies; 3 (2.6%) live births with congenital anomalies; 2 (1.7%) spontaneous abortions with no congenital anomalies; 1 (0.9%) spontaneous abortion with a congenital anomaly; 1 stillbirth with no apparent congenital anomaly; 7 (6.1%) ‘Unknown’. Results from 493 prospective reports received via worldwide spontaneous, passive surveillance showed similar outcomes. All cases with congenital anomaly were assessed as not likely/unlikely/unrelated to vaccination. Despite the limited number of cases and outcomes, no safety signal was identified. The study findings are aligned with previously published data and should be confirmed with other robust data sources.

What is the context?

The pneumococcus bacterium can cause infections of the meninges, blood, lung, middle ear and sinuses.

Two vaccins, Synflorix (GSK) and Prevnar 13 (Pfizer Inc.), are widely used to protect young children against these infections.

The vaccines’ compositions differ: Synflorix includes antigens from 10 pneumococcus strains (or “serotypes”) and Prevnar 13 from 13 serotypes.

However, both have a similar effect on the total pneumococcal disease burden in children.

What does this commentary highlight?

This commentary summarizes the evidence beihnd the two vaccines’ comparable impact on pneumococcal disase.

It also looks at why the vaccines have a similar effect on the total pneumococcal disease burden despite their different compositions.

What is the impact on current thinking?

Given that Synflorix and Prevnar 13 have a comparable impact on pneumococcal disease, a country’s choice between the two vaccines will depend on vaccine supply, cost, logistical factors (e.g., transport, storage, training requirements of health workers) and the local pneumococcal epidemiology.

Expert opinion on the way forward for improving maternal influenza vaccination in India

INTRODUCTION

: Rates of maternal vaccination against influenza are extremely low in India. An expert panel of obstetric-gynecologists and pediatricians met to develop consensus-based recommendations for improving awareness of the benefits of influenza vaccination during pregnancy in India.

AREAS COVERED

: The group discussed experiences of influenza infection in pregnancy and infancy before focusing on maternal vaccination practices in India, including the degree of communication between obstetric-gynecologists and pediatricians and opinions on optimal timing for vaccination. The impact of inconsistent vaccine prescription practices by healthcare providers was discussed, as well as current clinical recommendations on maternal influenza vaccination.

EXPERT OPINION

: Although clinical evidence demonstrates the benefit of maternal influenza vaccination in any trimester, influenza vaccination is not widely accepted in India as an integral part of antenatal care. There is a lack of familiarity among obstetricians of clinical guidelines on maternal influenza vaccination. This can be addressed with an education campaign targeting obstetricians and other providers of maternal healthcare. With variable influenza seasons between regions in India, common vaccine stock shortages, and data suggesting influenza vaccination is feasible anytime in pregnancy, all opportunities to offer vaccination to this high-risk group for severe influenza disease should be considered.

Reduced Placental Transfer of Antibodies Against a Wide Range of Microbial and Vaccine Antigens in HIV-Infected Women in Mozambique

Transplacental transfer of antibodies is essential for conferring protection in newborns against infectious diseases. We assessed the impact of different factors, including gestational age and maternal infections such as HIV and malaria, on the efficiency of cord blood levels and placental transfer of IgG subclasses. We measured total IgG and IgG subclasses by quantitative suspension array technology against 14 pathogens and vaccine antigens, including targets of maternal immunization, in 341 delivering HIV-uninfected and HIV-infected mother-infant pairs from southern Mozambique. We analyzed the association of maternal HIV infection, Plasmodium falciparum exposure, maternal variables and pregnancy outcomes on cord antibody levels and transplacental transfer. Our results show that maternal antibody levels were the main determinant of cord antibody levels. Univariable and multivariable analysis showed that HIV reduced the placental transfer and cord levels of IgG and IgG1 principally, but also IgG2 to half of the antigens tested. P. falciparum exposure and prematurity were negatively associated with cord antibody levels and placental transfer, but this was antigen-subclass dependent. Our findings suggest that lower maternally transferred antibodies may underlie increased susceptibility to infections of HIV-exposed infants. This could affect efficacy of maternal vaccination, especially in sub-Saharan Africa, where there is a high prevalence of HIV, malaria and unfavorable environmental factors.

Is the Host Viral Response and the Immunogenicity of Vaccines Altered in Pregnancy?

The intricacy of the maternal immune system arises from its ability to prevent a maternal immune response against a semi-allogenic fetus, while protecting the mother against harmful pathogens. However, these immunological adaptations may also make pregnant women vulnerable to developing adverse complications from respiratory viral infections. While the influenza and SARS pandemics support this theory, there is less certainty regarding the clinical impact of SARS-CoV-2 in pregnancy. In the current COVID-19 pandemic, vaccine development is key to public preventative strategies. Whilst most viral vaccines are able to induce a seroprotective antibody response, in some high-risk individuals this may not correlate with clinical protection. Some studies have shown that factors such as age, gender, and chronic illnesses can reduce their effectiveness and in this review, we discuss how pregnancy may affect the efficacy and immunogenicity of vaccines. We present literature to support the hypothesis that pregnant women are more susceptible to respiratory viral infections and may not respond to vaccines as effectively. In particular, we focus on the clinical implications of important respiratory viral infections such as influenza during pregnancy, and the pregnancy induced alterations in important leukocytes such as TFH, cTFH and B cells, which play an important role in generating long-lasting and high-affinity antibodies. Finally, we review how this may affect the efficacy of vaccines against influenza in pregnancy and highlight areas that require further research.

Preventive Allergen-Specific Vaccination Against Allergy: Mission Possible?

Vaccines for infectious diseases have improved the life of the human species in a tremendous manner. The principle of vaccination is to establish de novo adaptive immune response consisting of antibody and T cell responses against pathogens which should defend the vaccinated person against future challenge with the culprit pathogen. The situation is completely different for immunoglobulin E (IgE)-associated allergy, an immunologically-mediated hypersensitivity which is already characterized by increased IgE antibody levels and T cell responses against per se innocuous antigens (i.e., allergens). Thus, allergic patients suffer from a deviated hyper-immunity against allergens leading to inflammation upon allergen contact. Paradoxically, vaccination with allergens, termed allergen-specific immunotherapy (AIT), induces a counter immune response based on the production of high levels of allergen-specific IgG antibodies and alterations of the adaptive cellular response, which reduce allergen-induced symptoms of allergic inflammation. AIT was even shown to prevent the progression of mild to severe forms of allergy. Consequently, AIT can be considered as a form of therapeutic vaccination. In this article we describe a strategy and possible road map for the use of an AIT approach for prophylactic vaccination against allergy which is based on new molecular allergy vaccines. This road map includes the use of AIT for secondary preventive vaccination to stop the progression of clinically silent allergic sensitization toward symptomatic allergy and ultimately the prevention of allergic sensitization by maternal vaccination and/or early primary preventive vaccination of children. Prophylactic allergy vaccination with molecular allergy vaccines may allow halting the allergy epidemics affecting almost 30% of the population as it has been achieved for vaccination against infectious diseases.

Influenza Vaccination Experiences of Pregnant Women as a Predictor of the Intention to Become Vaccinated in Future Pregnancies in Spain

A good perception of the vaccines administered during pregnancy favors immunization coverage, which is still not optimal for the influenza vaccine. To understand the predisposition towards vaccination in future pregnancies, a study was performed that evaluated the experiences of women with the vaccine or influenza. A cross-sectional study was conducted through telephone interviews given to a total of 683 postpartum women in two health departments from the Valencia Community (Spain). This interview asked about their intention of becoming vaccinated in future pregnancies and whether they were favor or against vaccination. Most of them, 98.5% (n = 673 [95% CI: 97.6–99.4]) (p < 0.001) declared having received the systematic vaccines throughout their lives. The ones who were vaccinated against influenza, 91.9% (n = 387 [95% CI: 89.2–94.6]) (p < 0.001) manifested they would do so in future pregnancies. The probability of future non-vaccination was modeled, which was related to an unfavorable opinion towards vaccines (OR = 4.07 [95% CI: 2.01–8.24]) (p < 0.001), having suffered from influenza during pregnancy (OR = 3.84 [95% CI: 1.41–10.42]) (p < 0.05), and not having been vaccinated during previous pregnancies (OR = 38.47 [95% CI: 23.58–62.76]) (p < 0.001). Vaccination during pregnancy increases the intent of vaccination in the future.