Safety of immunization during pregnancy: a review of the evidence of selected inactivated and live attenuated vaccines

Pregnancy outcomes following unintentional exposure to TAK-003, a live-attenuated tetravalent dengue vaccine

BACKGROUND

The tetravalent dengue vaccine TAK-003 is contraindicated during pregnancy. Pregnant women were excluded from TAK-003 clinical studies; however, some pregnancies occurred unintentionally.

RESEARCH DESIGN AND METHODS

This post-hoc analysis of phase 2 and 3 studies, evaluated pregnancy outcomes and neonatal adverse events (AEs) following unintentional vaccination during the time period ('exposure window') when women could be pregnant (within 44 days before last menstrual period until the outcome of pregnancy).

RESULTS

Of the 557 reported pregnancies, 38 (TAK-003, n = 28/375; placebo, n = 10/182) occurred inside the exposure window. Of these, 28 (TAK-003, n = 23; placebo, n = 5) resulted in live births, four resulted in elective terminations (TAK-003, n = 2; placebo, n = 2), five in spontaneous abortions (TAK-003, n = 3; placebo, n = 2) and one unknown outcome (placebo).Of the spontaneous abortions, there was no significant difference between TAK-003 and placebo recipients, or between those occurring within or outside the exposure window. Six participants who received TAK-003 in the exposure window and two neonates experienced serious AEs; none were considered TAK-003 related.

CONCLUSIONS

This post-hoc analysis found no evidence of increased adverse pregnancy outcomes following unintentional TAK-003 vaccination occurring inside the exposure window compared with placebo.

CLINICAL TRIAL REGISTRATION

The clinical trials from which data were extracted are registered at www.clinicaltrials.gov (identifiers are NCT02193087, NCT01511250, NCT02302066, NCT02425098, NCT03746015, NCT02747927, NCT03999996, NCT03423173, NCT03342898, NCT03771963, NCT04313244, NCT02948829, NCT035252119, NCT03341637).

Maternal Immunization

Pregnant individuals and infants are at risk from vaccine-preventable diseases like severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza. Maternal vaccination during pregnancy can protect both the mother and child. Recent progress in developing these vaccines is notable, but vaccine hesitancy and the exclusion of pregnant individuals from clinical trials limit their use. Maternal immunization safeguards mothers from severe illness and adverse pregnancy outcomes while providing infants with antibodies through the placenta and breast milk. Inactivated vaccines are generally effective and safe during pregnancy. Limited safety and efficacy data due to exclusion from trials hinder vaccine uptake; however, vaccines like tetanus-diphtheria-acellular pertussis (Tdap), influenza, and SARS-CoV-2 have proven effective, and are recommended vaccines during pregnancy. New vaccines for group B Streptococcus (GBS) and cytomegalovirus are in development, with the GBS vaccine being the most advanced. Combating vaccine hesitancy through strong health care provider recommendations is vital to enhance uptake and protect pregnant individuals and their infants.

Research Priorities for Maternal Immunization

BACKGROUND

The maternal immunization platform has multiple vaccines already being utilized with more vaccines being considered.

METHODS

We describe areas with knowledge gaps regarding maternal immunization including (1) pathogen, (2) vaccine product, (3) vaccine strategy, (4) implementation research and (5) Regulatory and Public Health Policy.

RESULTS

Despite advances in clinical research during pregnancy, many questions remain regarding vaccine administration, products, coadministration of vaccines and vaccine acceptance. Issues regarding maternal antibody transfer in high-risk pregnancies need further study.

CONCLUSIONS

Moving new maternal vaccines forward will take support from a broad array of experts.

Pharmacovigilance for Vaccines Used in Pregnancy: A Gap Analysis From Uganda

BACKGROUND

Despite the effectiveness of maternal vaccines, low- and middle-income countries grapple with inadequate safety monitoring systems. Robust safety surveillance is crucial to increasing vaccine confidence and timely identifying any potential safety signal that could put pregnant women and children at risk following vaccination. This study assessed the pharmacovigilance (PV) systems for vaccines used in pregnancy in Uganda.

METHODS

A qualitative study involves 13 key informant interviews and 8 focus group discussions among key stakeholders. Purposive sampling was used to select study participants. Data analysis was done using Miles and Huberman's matrices approach and conducted in Atlas.ti software.

FINDINGS

A passive system involving multistakeholders at various levels of the healthcare structure existed but was inadequate for monitoring adverse events following maternal immunization. The existence of parallel reporting systems for vaccines was noted. Heavy workload, lack of feedback, inadequate knowledge to recognize and report adverse events following maternal immunizations and logistical challenges impeding reporting and follow-up were among the barriers to reporting. Electronic medical records, though underutilized for safety surveillance, offer promising potential.

CONCLUSIONS

To address the specific needs of maternal vaccination, the PV system in Uganda needs improvement. A multipronged approach, including policy coherence, embracing active surveillance and leveraging existing birth outcome surveillance and electronic medical records, is essential. Harnessing healthcare provider knowledge and advisory committee capacity in causality assessment is also necessary. The study findings can inform priority interventions to enhance PV for existing and new maternal vaccines.

Vaccine Acceptance Among Pregnant Women in Israel During COVID-19: Influences and Decision-Making Factors

Background and Objectives: In response to the COVID-19 pandemic, Israel prioritized pregnant women for vaccination, recognizing them as a high-risk group. This study aims to explore factors influencing the acceptance of Influenza, Pertussis (T-dap), and COVID-19 vaccines among pregnant women, focusing on attitudes, social norms, perceived control, and risk perceptions. Additionally, the study compares acceptance patterns between traditional vaccines and the newer COVID-19 vaccine. Methods: A prospective cohort study was conducted between December 2019 and December 2021 involving 449 predominantly Israeli pregnant women. A survey was administered to gather data on demographics, obstetric history, vaccination history, and factors influencing vaccination decisions. Results: COVID-19 vaccine uptake was the highest at 64% (202/314), followed by T-dap at 49% (221/449) and Influenza at 32% (146/449). Multivariable logistic regression showed that non-religious women and those with academic education were more likely to accept vaccines, especially the COVID-19 vaccine. Physician recommendations were the most influential factor in vaccine acceptance, while internet and media sources played a significant role in shaping COVID-19 vaccine decisions. Perceived risks varied: Whooping Cough was seen as the greatest threat to newborns, while COVID-19 posed the highest risk to mothers. Analyzing maternal and neonatal disease perception using multivariable linear regression, we found that information on maternal and neonatal Flu, Whooping Cough, and COVID-19 was significantly positively correlated with disease perception for each condition. Conclusions: Healthcare providers play a crucial role in influencing vaccine decisions, especially through personalized communication. Strategies targeting religious communities and leveraging media can help address vaccine hesitancy, ultimately improving maternal and neonatal health outcomes.

Impact of the US Maternal Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis (Tdap) Vaccination Program on Preventing Pertussis in Infants 2 to <6 Months of Age: A Case-Control Evaluation

Background

To protect infants aged <2 months against pertussis, the United States recommends Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) vaccination during each pregnancy. Data are limited on the strategy's effectiveness against pertussis in infants aged ≥2 months.

Methods

Pertussis case infants aged 2 to <6 months with cough onset between 1 January 2011 and 31 December 2014 were identified in 6 US states. Controls were 2 to <6 months of age, hospital matched, and selected by birth certificate. Mothers were interviewed to collect demographic and healthcare information. Provider-verified vaccination history was obtained for infants and mothers. Adjusted odds ratios (aORs) were calculated using conditional logistic regression; overall vaccine effectiveness (VE) was estimated as (1 - aOR)×100. To describe maternal Tdap VE modified by infant DTaP (diphtheria and tetanus toxoids and acellular pertussis) doses, case-control sets were unmatched, and a time-to-event analysis was conducted through a generalized linear mixed model.

Results

A total of 335 cases and 927 controls were enrolled. The overall adjusted VE estimate for Tdap during pregnancy was 45.6% (95% confidence interval [CI], 5.8%-68.5%) and increased slightly, but not significantly, against infant hospitalization (55.7% [-116.8% to 90.9%]). Although point estimates were not significant, VE was modified by infant DTaP doses (58.8% [95% CI, -6.0% to 84.0%] for 0 DTaP doses, 30.5% [-21.4% to 60.2%] for 1 dose, and 3.2% [-170.8% to 65.4%] for 2 doses).

Conclusions

Our study suggests that there is some benefit of maternal Tdap vaccination beyond the first 2 months of life, however, on-time vaccination of infants remains critical to maintain protection from pertussis.

Knowledge, attitudes, and practices (KAP) towards seasonal influenza and influenza vaccine among pregnant women in Kyrgyzstan: A cross-sectional study

Influenza is an acute respiratory disease of global importance due to its pandemic potential. Pregnant women are more susceptible to severe illness and adverse outcomes of influenza, and vaccination is the most effective preventive measure for mother and infant. The coverage rate of influenza immunization in Kyrgyzstan is below national targets, despite the World Health Organization's (WHO) recommendation to prioritize pregnant women for vaccination. This study sought to understand drivers and barriers to influenza vaccine uptake in pregnant women in Kyrgyzstan. A knowledge, attitudes, and practices (KAP) survey was administered from December 2018 to March 2019 to 1,193 pregnant women aged 18 and older attending public health institutions in Kyrgyzstan. Multivariate regression analysis was used to determine the association between variables and outcomes of interest.Nearly half (56.2 %) of the 1,193 participants expressed willingness to be vaccinated during their current pregnancy. Participants with only a high school education had a significantly greater intention for vaccination (95 % CI: 1.4-3.2, p < 0.005) in the multivariate analysis compared to participants with university degrees. Participants with underlying health conditions had a higher intention of being vaccinated (95 % CI: 1.2-1.9, p < 0.005). The main reason for vaccine refusal was the belief that influenza vaccines could have adverse effects on the fetus (28.4 %); belief that vaccines could harm their pregnancy (24.3 %); and concern about vaccine effectiveness (10.6 %).These findings are important as they can inform targeted strategies and policy updates to facilitate influenza vaccine implementation and improve uptake among pregnant women in Kyrgystan, and may support strengthening of national influenza vaccine programs in other countries in Central Asia.

Successful Elimination of Endemic Rubella in the WHO European Region. Is It Proper to Remove the Recommendation for Preconceptional Immunization?

BACKGROUND

Rubella is a contagious viral infection that has garnered significant attention in the field of public health due to its potential consequences, especially during pregnancy. In recent decades, it has been recommended that non-immune women receive immunization during the preconceptional and/or postpartum periods. The goal of this strategy is to prevent primary rubella infection in order to protect pregnant women against congenital rubella syndrome. In November 2022, the WHO's Regional Verification Commission declared the elimination of rubella infection in Italy. In recent years, the main migration flows to Italy have originated from regions where rubella has not yet been eliminated and where no program is in place to achieve this goal.

OBJECTIVE

The aim of this study was to retrospectively assess rubella immunity in pregnant women who have attended three delivery centers in Rome over the past three years, from January 2021 to May 2023.

METHODS

Data about the rubella serological status of 7937 non-consecutive pregnant women were collected. Univariate analysis was performed to verify any difference between the study groups in terms of age distribution.

RESULTS

Anti-rubella IgG antibodies were found in 7224 (91%) women while 713 (9%) were susceptible to rubella (IgG negative), without differences in terms of immunity rate between Italian and non-Italian women. Age analysis showed a statistically significant older age of immune women than receptive women and of Italian immune women than non-Italian immune women.

CONCLUSIONS

The National Plan for the Elimination of Measles and Congenital Rubella aimed to achieve a percentage of susceptible women of childbearing age below 5%. These data indicate the relevance of maintaining the recommendation for preconceptional rubella vaccination in Italy.

Attitude to Co-Administration of Influenza and COVID-19 Vaccines among Pregnant Women Exploring the Health Action Process Approach Model

Respiratory tract diseases caused by influenza virus and SARS-CoV-2 can represent a serious threat to the health of pregnant women. Immunological remodulation for fetus tolerance and physiological changes in the gestational chamber expose both mother and child to fearful complications and a high risk of hospitalization. Vaccines to protect pregnant women from influenza and COVID-19 are strongly recommended and vaccine co-administration could be advantageous to increase coverage of both vaccines. The attitude to accept both vaccines is affected by several factors: social, cultural, and cognitive-behavioral. In Palermo, Italy, during the 2021-2022 influenza season, a cross-sectional study was conducted to evaluate pregnant women's intention to adhere to co-administration of influenza and COVID-19 vaccines. The determinants of vaccination attitude were investigated through the administration of a questionnaire and the Health Action Process Approach theory was adopted to explore the cognitive behavioral aspects. Overall, 120 pregnant women were enrolled; mean age 32 years, 98.2% (n = 118) of Italian nationality and 25.2% (n = 30) with obstetric or pathological conditions of pregnancy at risk. Factors significantly associated with the attitude to co-administration of influenza and COVID-19 vaccines among pregnant women were: high level of education (OR = 13.96; p < 0.001), positive outcome expectations (OR = 2.84; p < 0.001), and self-efficacy (OR = 3.1; p < 0.001). Effective strategies to promote the co-administration of the influenza vaccine and the COVID-19 vaccine should be based on the communication of the benefits and positive outcomes of vaccine co-administration and on the adequate information of pregnant women.

Facilitators and barriers to vaccination uptake in pregnancy: A qualitative systematic review

INTRODUCTION

Vaccination during pregnancy protects both the mother and the foetus from vaccine-preventable diseases. However, uptake of the recommended vaccines (influenza, pertussis, COVID-19) by pregnant women remains low in Europe and the USA. Understanding the reasons for this is crucial to inform strategies to increase vaccination rates in pregnant women. This qualitative systematic review aimed to identify the barriers and facilitators to vaccination against influenza, pertussis/whooping cough and COVID-19 during pregnancy and identify possible strategies to increase vaccination rates.

METHODS

We conducted a comprehensive search of electronic databases, including Medline, PsycINFO, CINAHL, Web of Science, WHO database, Embase and grey literature to identify qualitative studies that explored barriers and facilitators to vaccine uptake among pregnant women (PROSPERO CRD42023399488). The search was limited to studies published between 2012 and 2022 conducted in high-income countries with established vaccination programmes during pregnancy. Studies were thematically analysed and underwent quality assessment using the Joanna Briggs Institute validated critical appraisal tool for qualitative research.

RESULTS

Out of 2681 articles screened, 28 studies (n = 1573 participants) were eligible for inclusion. Five overarching themes emerged relating to personal, provider and systemic factors. Barriers to vaccine uptake included concerns about vaccine safety and efficacy, lack of knowledge about vaccines' benefits and necessity, fear of adverse effects on the foetus or mother and low perception of disease severity. Facilitators included recommendations from trusted healthcare providers, easy access to vaccination, clear communication on the benefits and safety of vaccination, and positive social influences from family and friends. Strategies for increasing vaccination uptake included strong and proactive vaccine recommendations by trusted healthcare professionals, provision of vaccines during routine antenatal care, and clear and consistent communication about vaccines addressing pregnant women's concerns.

CONCLUSION

This review highlights the need for interventions that address the identified barriers to vaccine uptake among pregnant women. Recommendation from a healthcare provider can play a significant role in promoting vaccine uptake, as can clear risk/benefit communication and convenient access to vaccination. Addressing concerns about vaccine safety and providing accurate information about vaccines is also important.

Pregnancy Outcomes among Pregnant Persons after COVID-19 Vaccination: Assessing Vaccine Safety in Retrospective Cohort Analysis of U.S. National COVID Cohort Collaborative (N3C)

COVID-19 vaccines have been shown to be effective in preventing severe illness, including among pregnant persons. The vaccines appear to be safe in pregnancy, supporting a continuously favorable overall risk/benefit profile, though supportive data for the U.S. over different periods of variant predominance are lacking. We sought to analyze the association of adverse pregnancy outcomes with COVID-19 vaccinations in the pre-Delta, Delta, and Omicron SARS-CoV-2 variants' dominant periods (constituting 50% or more of each pregnancy) for pregnant persons in a large, nationally sampled electronic health record repository in the U.S. Our overall analysis included 311,057 pregnant persons from December 2020 to October 2023 at a time when there were approximately 3.6 million births per year. We compared rates of preterm births and stillbirths among pregnant persons who were vaccinated before or during pregnancy to persons vaccinated after pregnancy or those who were not vaccinated. We performed a multivariable Poisson regression with generalized estimated equations to address data site heterogeneity for preterm births and unadjusted exact models for stillbirths, stratified by the dominant variant period. We found lower rates of preterm birth in the majority of modeled periods (adjusted incidence rate ratio [aIRR] range: 0.42 to 0.85; p-value range: <0.001 to 0.06) and lower rates of stillbirth (IRR range: 0.53 to 1.82; p-value range: <0.001 to 0.976) in most periods among those who were vaccinated before or during pregnancy compared to those who were vaccinated after pregnancy or not vaccinated. We largely found no adverse associations between COVID-19 vaccination and preterm birth or stillbirth; these findings reinforce the safety of COVID-19 vaccination during pregnancy and bolster confidence for pregnant persons, providers, and policymakers in the importance of COVID-19 vaccination for this group despite the end of the public health emergency.

Prenatal Maternal Immunization for Infant Protection: A Review of the Vaccines Recommended, Infant Immunity and Future Research Directions

Prenatal maternal immunization is an effective tool to protect mothers and infants from poor health outcomes due to infectious diseases. We provide an overview of the rationale for the use of prenatal vaccines, discuss the immunologic environment of the maternal-fetal interface including the impact of maternal vaccines prenatally and subsequently on the infant's immune response, and review vaccines currently recommended in pregnancy and landscape for the future of maternal vaccination. This review aims to provide an understanding of the recent history and progress made in the field and highlight the importance of continued research and development into new vaccines for pregnant populations.

MA, Tovar-Rosero YY, Oñate AA, O'Ryan M. Two centuries of vaccination: historical and conceptual approach and future perspectives

Over the past two centuries, vaccines have been critical for the prevention of infectious diseases and are considered milestones in the medical and public health history. The World Health Organization estimates that vaccination currently prevents approximately 3.5-5 million deaths annually, attributed to diseases such as diphtheria, tetanus, pertussis, influenza, and measles. Vaccination has been instrumental in eradicating important pathogens, including the smallpox virus and wild poliovirus types 2 and 3. This narrative review offers a detailed journey through the history and advancements in vaccinology, tailored for healthcare workers. It traces pivotal milestones, beginning with the variolation practices in the early 17th century, the development of the first smallpox vaccine, and the continuous evolution and innovation in vaccine development up to the present day. We also briefly review immunological principles underlying vaccination, as well as the main vaccine types, with a special mention of the recently introduced mRNA vaccine technology. Additionally, we discuss the broad benefits of vaccines, including their role in reducing morbidity and mortality, and in fostering socioeconomic development in communities. Finally, we address the issue of vaccine hesitancy and discuss effective strategies to promote vaccine acceptance. Research, collaboration, and the widespread acceptance and use of vaccines are imperative for the continued success of vaccination programs in controlling and ultimately eradicating infectious diseases.

SARS-CoV-2 neutralizing antibody titers in maternal blood, umbilical cord blood, and breast milk

OBJECTIVE

We quantified neutralizing SARS-CoV-2 antibody against spike protein (nAb) levels after vaccination and SARS-CoV-2 infection in maternal serum, cord blood, and breast milk and determined whether they correlate with levels of spike protein binding antibody.

STUDY DESIGN

Women (n = 100) were enrolled on admission for delivery. Previous SARS-CoV-2 infection was defined by anti-nucleocapsid antibodies. Levels of nAb and binding antibodies against spike receptor binding domain were measured in maternal blood, cord blood, and milk.

RESULTS

Maternal nAb levels were higher after vaccine and infection than vaccine alone but waned rapidly. Levels of nAb in cord blood and milk correlated with maternal levels and were higher in cord blood than maternal. Spike protein binding antibody levels correlated with nAb.

CONCLUSION

SARS-CoV-2 vaccination near delivery may boost antibody-mediated immunity in the peripartum period. Neutralizing antibodies are passed transplacentally and into milk. Spike protein binding antibody may be a feasible proxy for nAb.

Maternal immune factors involved in the prevention or facilitation of neonatal bacterial infections

Newborns, whether born prematurely or at term, have a fully formed but naive immune system that must adapt to the extra-uterine environment to prevent infections. Maternal immunity, transmitted through the placenta and breast milk, protects newborns against infections, primarily via immunoglobulins (IgG and IgA) and certain maternal immune cells also known as microchimeric cells. Recently, it also appeared that the maternal gut microbiota played a vital role in neonatal immune maturation via microbial compounds impacting immune development and the establishment of immune tolerance. In this context, maternal vaccination is a powerful tool to enhance even more maternal and neonatal health. It involves the transfer of vaccine-induced antibodies to protect both mother and child from infectious diseases. In this work we review the state of the art on maternal immune factors involved in the prevention of neonatal bacterial infections, with particular emphasis on the role of maternal vaccination in protecting neonates against bacterial disease.

Interventions to increase vaccination against COVID-19, influenza and pertussis during pregnancy: a systematic review and meta-analysis

BACKGROUND

Pregnant women and their babies face significant risks from three vaccine-preventable diseases: COVID-19, influenza and pertussis. However, despite these vaccines' proven safety and effectiveness, uptake during pregnancy remains low.

METHODS

We conducted a systematic review (PROSPERO CRD42023399488; January 2012-December 2022 following PRISMA guidelines) of interventions to increase COVID-19/influenza/pertussis vaccination in pregnancy. We searched nine databases, including grey literature. Two independent investigators extracted data; discrepancies were resolved by consensus. Meta-analyses were conducted using random-effects models to estimate pooled effect sizes. Heterogeneity was assessed using the I2 statistics.

RESULTS

From 2681 articles, we identified 39 relevant studies (n = 168 262 participants) across nine countries. Fifteen studies (39%) were randomized controlled trials (RCTs); the remainder were observational cohort, quality-improvement or cross-sectional studies. The quality of 18% (7/39) was strong. Pooled results of interventions to increase influenza vaccine uptake (18 effect estimates from 12 RCTs) showed the interventions were effective but had a small effect (risk ratio = 1.07, 95% CI 1.03, 1.13). However, pooled results of interventions to increase pertussis vaccine uptake (10 effect estimates from six RCTs) showed no clear benefit (risk ratio = 0.98, 95% CI 0.94, 1.03). There were no relevant RCTs for COVID-19. Interventions addressed the 'three Ps': patient-, provider- and policy-level strategies. At the patient level, clear recommendations from healthcare professionals backed by text reminders/written information were strongly associated with increased vaccine uptake, especially tailored face-to-face interventions, which addressed women's concerns, dispelled myths and highlighted benefits. Provider-level interventions included educating healthcare professionals about vaccines' safety and effectiveness and reminders to offer vaccinations routinely. Policy-level interventions included financial incentives, mandatory vaccination data fields in electronic health records and ensuring easy availability of vaccinations.

CONCLUSIONS

Interventions had a small effect on increasing influenza vaccination. Training healthcare providers to promote vaccinations during pregnancy is crucial and could be enhanced by utilizing mobile health technologies.

Vaccine value profile for Group B streptococcus

Group B streptococcus (GBS) is a major global cause of neonatal meningitis, sepsis and pneumonia, with an estimated 91,000 infant deaths per year and an additional 46,000 stillbirths. GBS infection in pregnancy is also associated with adverse maternal outcomes and preterm births. As such, the World Health Organization (WHO) prioritised the development of a GBS vaccine suitable for use in pregnant women and use in LMICs, where the burden of disease is highest. Several GBS vaccines are in clinical development. The WHO Defeating Meningitis by 2030 has set a target of 2026 for vaccine licensure. This 'Vaccine Value Profile' (VVP) for GBS is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships and multi-lateral organizations, and in collaboration with stakeholders from the WHO regions of AFR, AMR, EUR, WPR. All contributors have extensive expertise on various elements of the GBS VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.

Vaccine safety surveillance in Kenya using GAIA standards: A feasibility assessment of existing national and subnational research and program systems

BACKGROUND

Active surveillance systems for monitoring vaccine safety among pregnant women address some of the limitations of a current passive surveillance approach utilized in low- and middle-income countries (LMIC). However, few active surveillance systems in LMIC exist. Our study assessed the feasibility of utilizing three existing data collection systems in Kenya for active surveillance of maternal immunization and to assess the applicability of Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) case definitions that were initially developed for clinical trials within these systems.

METHODS

We assessed applicability of GAIA case definition for maternal Tetanus Toxoid exposure, stillbirth, low birth weight, small for gestational age, Neonatal Invasive Blood Stream Infection (NIBSI), prematurity and neonatal death in two routine web-based health information systems (Kenya EMR and DHIS-2), and a web-based population-based pregnancy research platform (ANCOV1) in Kenya.

RESULTS

All three HIS were capable of reporting selected outcomes to varying degrees of GAIA certainty. The ANCOV platform was the most robust in collecting and collating clinical data for effective maternal pharmacovigilance. The utilization of facility- and district-aggregated data limits the usefulness of DHIS-2 in pharmacovigilance as currently operationalized. While the Kenya EMR contained individual level data and meets the key considerations for effective pharmacovigilance, it was used primarily for HIV care and treatment records in a small proportion of health facilities and would require additional resources to expand to all antenatal care facilities and to link maternal and infant records.

DISCUSSION

Population-based research studies may offer a responsive short-term option for implementing maternal vaccine pharmacovigilance in LMICs. However, the foundation exists for long-term capacity building within the national health electronic data systems to provide this critical service as well as ensure participation of the country in international studies on maternal vaccine safety.

A safe replication-defective Zika virus vaccine protects mice from viral infection and vertical transmission

With the explosive emergence of Zika virus (ZIKV) and the consequent devastating fetal malformations in infected expectant women, a safe and effective vaccine is urgently needed. Here, using our established NS1 trans-complementation system, we generated high titer of replication-defective ZIKV with NS1 deletion (ZIKV-ΔNS1) in the BHK-21 cell line stably expressing NS1 (BHK_NS1). NS1 deletion of ZIKV-ΔNS1 was stably maintained as no replicative virus was found in naïve BHK-21 cells after continuous passaging of ZIKV-ΔNS1 in BHK_NS1 cells. The safety of ZIKV-ΔNS1 was demonstrated when a high dose of ZIKV-ΔNS1 (10⁷ IU) was used to infect the highly susceptible type I and type II interferon (IFN) receptor-deficient mice. ZIKV-ΔNS1 could induce antibody responses in both immunocompetent (BALB/c) and immunodeficient mice and a single dose of ZIKV-ΔNS1 vaccine protected the immunodeficient mice from a highly lethal dosage of challenge with WT ZIKV. ZIKV-ΔNS1 immunization also attenuated vertical transmission during pregnancy of type I IFN receptor-deficient IFNAR^-/- mice and protected fetuses from ZIKV infection. Our data reported here not only provide a promising ZIKV vaccine candidate with a satisfied balance between safety and efficacy, but also demonstrate the potential of the NS1 trans-complementation system as a platform for flavivirus vaccine development, especially for highly pathogenic flaviviruses.

Strategies to Prevent Early and Late-Onset Group B Streptococcal Infection via Interventions in Pregnancy

Group B Streptococcus is a Gram-positive bacterium that typically colonizes 10-30% of pregnant women, causing chorioamnionitis, preterm birth, and stillbirth, as well as neonatal sepsis and meningitis with early-onset disease (EOD) or late-onset disease (LOD) due to ascending infection or transmission during delivery. While there are some differences between EOD and LOD in terms of route of transmission, risk factors, and serotypes, the only preventive approach currently is maternal intrapartum antibiotic prophylaxis (IAP) which will not be able to fully address the burden of the disease since this has no impact on LOD. Probiotics and immunization in pregnancy may be more effective than IAP for both EOD and LOD. There is mixed evidence of probiotic effects on the prevention of GBS colonization, and the data from completed and ongoing clinical trials investigating different GBS vaccines are promising. Current vaccine candidates target bacterial proteins or the polysaccharide capsule and include trivalent, tetravalent, and hexavalent protein-polysaccharide conjugate vaccines. Some challenges in developing novel GBS vaccines include the lack of a correlate of protection, the potential for serotype switching, a need to understand interactions with other vaccines, and optimal timing of administration in pregnancy to maximize protection for both term and preterm infants.

Factors associated with COVID-19 vaccination likelihood during pregnancy

OBJECTIVE

To identify maternal background, medical and gynecological characteristics associated with COVID-19 vaccination likelihood, in the context where COVID-19 vaccination rates among pregnant women are significantly lower than the general population.

METHODS

In a retrospective cohort study, including all women who delivered between January and September 2021, background and medical history, including current and previous pregnancies diagnoses, were compared between vaccinated and unvaccinated women. Multivariable logistic models were used to identify factors associated with vaccination for the entire population, and for the two distinctive populations included in the study (Bedouin Arabs and Jewish women).

RESULTS

The study population included 7017 women, of whom 1925 (27.4%) were vaccinated during pregnancy. According to the multivariable analysis, unvaccinated mothers were younger with lower socioeconomic score. They were more likely to be Bedouin Arabs, have a poor obstetrical history or recurrent pregnancy loss, and insufficient prenatal care. Additional risk factors were inconsistent between the two ethnicities included in the study.

CONCLUSIONS

Ethnicity, insufficient prenatal care, and having a poor obstetric history were consistently associated with lower vaccination among pregnant women. These factors should be considered in future plans aimed at increasing vaccination among pregnant women.

Detection of SARS-CoV-2 Neutralizing Antibodies in Vaccinated Pregnant Women and Neonates by Using a Lateral Flow Immunoassay Coupled with a Spectrum-Based Reader

The focus of this study was to investigate the detection of neutralizing antibodies (Nabs) in maternal serum and cord blood as the targeted samples by employing a lateral flow immunoassay combined with a spectrum reader (LFI-SR) and the correlation of Nab protection against different types of SARS-CoV-2. We enrolled 20 pregnant women who were vaccinated with the Moderna (mRNA-1273) vaccine during pregnancy and collected 40 samples during delivery. We used an LFI-SR for the level of spike protein receptor binding domain antibody (SRBD IgG) as Nabs and examined the correlation of the SRBD IgG concentration and Nab inhibition rates (NabIR) via enzyme-linked immunosorbent assays (ELISA). The LFI-SR had high confidence for the SRBD IgG level (p < 0.0001). Better NabIR were found in wild-type SARS-CoV-2 (WT) compared to Delta-type (DT) and Omicron-type (OT). Women with two-dose vaccinations demonstrated greater NabIR than those with a single dose. The cut-off value of the SRBD IgG level by the LFI-SR for NabIR to DT (≥30%; ≥70%) was 60.15 and 150.21 ng/mL for mothers (both p = 0.005), and 156.31 (p = 0.011) and 230.20 ng/mL (p = 0.006) for babies, respectively. An additional vaccine booster may be considered for those mothers with SRBD IgG levels < 60.15 ng/mL, and close protection should be given for those neonates with SRBD IgG levels < 150.21 ng/mL, since there is no available vaccine for them.

The effects of inactivated SARS-CoV-2 vaccination and subsequent infection of pregnant mice on the behaviors of offspring

The mass inoculation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines to induce herd immunity is one of the most effective measures we can deploy in the fight against coronavirus disease 2019 (COVID-19). Pregnant women are prone to a higher risk of COVID-19, and maternal infection is a risk factor for a range of neurological disorders leading to abnormal behavior in adulthood. However, there are limited clinical data to support whether vaccination or infection post-immunization in pregnant women can affect the behavioral cognition of fetuses in adulthood. In this study, human angiotensin-converting enzyme 2 pregnant mice (F0 generation) were immunized with CoronaVac and then infected with SARS-CoV-2. Subsequently, we analyzed the behavioral cognition of their adult offspring (F1 generation) using the open-field test and Morris water maze test. The adult F1 generation did not exhibit any impairments in spontaneous locomotor activity or spatial reference memory.

Antibodies against SARS-CoV-2 Alpha, Beta, and Gamma Variants in Pregnant Women and Their Neonates under Antenatal Vaccination with Moderna (mRNA-1273) Vaccine

The aim of the study was to examine the impact of COVID-19 vaccination on the anti-SARS-CoV-2 spike receptor binding domain IgG antibody (SRBD IgG) binding ratio (SBR) from Alpha, Beta, and Gamma variants of SARS-CoV-2 in pregnant women and neonates. The impact of antenatal influenza (flu) and pertussis (Tdap) vaccines was also studied. We enrolled pregnant women vaccinated with the Moderna (mRNA-1273) vaccine during pregnancy and collected maternal plasma (MP) and neonatal cord blood (CB) during delivery to determine the SBR via enzyme-linked immunosorbent assays (ELISA). A total of 78 samples were collected from 39 pregnant women. The SBR was higher for Alpha variants compared to Beta/Gamma variants (MP: 63.95% vs. 47.91% vs. 43.48%, p = 0.0001; CB: 72.14% vs. 56.78% vs. 53.66%, p = 0.006). Pregnant women receiving two doses of the COVID-19 vaccine demonstrated a better SBR against SARS-CoV-2 Alpha, Beta, and Gamma variants than women receiving just a single dose. Women who received the Tdap/flu vaccines demonstrated a better SBR when two COVID-19 vaccine doses were < 6 weeks apart. A better SBR was detected among women who had more recently received their second COVID-19 vaccine dose. Two doses of the COVID-19 vaccine provided recipients with a better SBR for Alpha/Beta/Gamma variants. Although Tdap/flu vaccines may affect the efficacy of the COVID-19 vaccine, different vaccination timings can improve the SBR.

Operational lessons learned in conducting an international study on pharmacovigilance in pregnancy in resource-constrained settings: The WHO Global Vaccine safety Multi-Country collaboration project

The WHO Global Vaccine Safety Multi-Country Collaboration study on safety in pregnancy aims to estimate the minimum detectable risk for selected perinatal and neonatal outcomes and assess the applicability of standardized case definitions for study outcomes and maternal immunization in low- and middle-income countries (LMICs). This paper documents the operational lessons learned from the study. A prospective observational study was conducted across 21 hospitals in seven countries. All births occurring at sites were screened to identify select perinatal and neonatal outcomes from May 2019 to August 2020. Up to 100 cases per outcome were recruited to assess the applicability of standardized case definitions. A multi-pronged study quality assurance plan was implemented. The impact of the COVID-19 pandemic on site functioning and project implementation was also assessed. Multi-layered ethics and administrative approvals, limited clinical documentation, difficulty in identifying outcomes requiring in-hospital follow-up, and poor quality internet connectivity emerged as important barriers to study implementation. Use of electronic platforms, application of a rigorous quality assurance plan with frequent interaction between the central and site teams helped improve data quality. The COVID-19 pandemic disrupted data collection for up to 6 weeks in some sites. Our study succeeded in establishing an international hospital-based surveillance network for evaluating perinatal and neonatal outcomes using common study protocol and procedures in geographically diverse sites with differing levels of infrastructure, clinical and health-utilization practices. The enhanced surveillance capacity of participating sites shall help support future pharmacovigilance efforts for pregnancy interventions.

Risk Measurement of Perinatal and Neonatal Morbidity Characteristics and Applicability of GAIA Case Definitions: Results and Lessons Learnt of a Hospital-Based Prospective Cohort Study in the Valencia Region (2019-2020)

Post-marketing safety surveillance of new vaccines aimed to be administered during pregnancy is crucial to orchestrate efficient adverse events evaluation. This is of special relevance in the current landscape of new vaccines being introduced in the pregnant women population, and particularly due to the recent administration of COVID-19 vaccines in pregnant women. This multi-center prospective cohort study, nested within the WHO-Global Vaccine Safety-MCC study, involved two hospitals in the Valencia region. Hereby, the incidence rates of seven perinatal and neonatal outcomes in the Valencia region are presented. The pooled data analysis of the two Valencian hospitals allowed the estimation of incidence rates in the Valencia Region (per 1000 live births): 86.7 for low birth weight, 78.2 for preterm birth, 58.8 for small for gestational age, 13 for congenital microcephaly, 0.4 for stillbirth, 1.2 for neonatal death and 6.5 for neonatal infection. These figures are in line with what is expected from a high-income country and the previously reported rates for Spain and Europe, except for the significantly increased rate for congenital microcephaly. Regarding the data for maternal immunization, the vaccination status was collected for 94.4% of the screened pregnant women, highlighting the high quality of the Valencian Vaccine Registry. The study also assessed the Valencian hospitals’ capacity for identifying and collecting data on maternal immunization status, as well as the applicability of the GAIA definitions to the identified outcomes.

Suboptimal Vaccination Administration in Mothers With Inflammatory Bowel Disease and Their Biologic-Exposed Infants

BACKGROUND

Pregnant women with inflammatory bowel disease (IBD) are at increased risk of developing complications from vaccine-preventable infections. We investigated the factors influencing vaccine administration in pregnant women with IBD and their infants, in addition to the safety of vaccination in the infants.

METHODS

This retrospective cohort study identified individuals from a tertiary referral clinic whose records were linked to a provincial vaccine database. We conducted χ 2 tests, Fisher exact tests, and logistic regression adjusting for age and disease duration to compare vaccine administration by medication class. Potential rotavirus vaccine adverse events were determined in infants of women with IBD.

RESULTS

We included 303 pregnant women and 262 infants. Vaccines were administered to women on biologic therapy as follows: hepatitis B virus (82.9%), diphtheria-tetanus-pertussis (82.1%), and hepatitis A virus (49.3%). The influenza vaccination was provided peripartum in 50.7% of patients. The measles-mumps-rubella-varicella vaccine was provided to 89.3% of women before biologic initiation. Women treated with a biologic (adjusted odds ratio, 2.50; 95% confidence interval, 1.39-4.35) or immunomodulator (adjusted odds ratio, 4.00; 95% confidence interval, 2.22-7.69) were more likely to receive the Prevnar 13 and Pneumovax 23 vaccines than were unexposed individuals, but the overall proportion vaccinated was low (Prevnar 13, 35.7%; Pneumovax 23, 39.3%). At least 90% of infants received the measles-mumps-rubella-varicella vaccine and inactivated vaccines. Fourteen biologic-exposed children (19.2%) received the live rotavirus vaccine with no significant differences in adverse events compared with biologic-unexposed infants (7.1% vs 8.2%, P = 0.99).

CONCLUSIONS

Better education surrounding vaccine recommendations is required for both health care providers and individuals with IBD given poor pneumococcal, hepatitis A virus, and influenza vaccination rates. Inadvertent administration of the rotavirus vaccine in biologic-exposed infants did not result in more adverse events, raising the possibility of safety.

WHO global vaccine safety multi-country collaboration project on safety in pregnancy: Assessing the level of diagnostic certainty using standardized case definitions for perinatal and neonatal outcomes and maternal immunization

Standardized case definitions strengthen post-marketing safety surveillance of new vaccines by improving generated data, interpretation and comparability across surveillance systems. The Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) project developed standardized case definitions for 21 key obstetric and neonatal terms following the Brighton Collaboration (BC) methodology. In this prospective cohort study, we assessed the applicability of GAIA definitions for maternal immunization exposure and for low birth weight (LBW), preterm birth, small for gestational age (SGA), stillbirth, neonatal death, neonatal infection, and congenital microcephaly. We identified the missing data elements that prevented identified cases and exposures from meeting the case definition (level 1-3 of BC diagnostic certainty). Over a one-year period (2019-2020), all births occurring in 21 sites (mostly secondary and tertiary hospitals) in 6 Low Middle Income Countries and 1 High Income Country were recorded and the 7 perinatal and neonatal outcome cases were identified from routine medical records. Up to 100 cases per outcome were recruited sequentially from each site. Most cases recruited for LBW, preterm birth and neonatal death met the GAIA case definitions. Birth weight, a key parameter for all three outcomes, was routinely recorded at all sites. The definitions for SGA, stillbirth, neonatal infection (particularly meningitis and respiratory infection) and congenital microcephaly were found to be less applicable. The main barrier to obtaining higher levels of diagnostic certainty was the lack of sonographic documentation of gestational age in first or second trimester. The definition for maternal immunization exposure was applicable, however, the highest level of diagnostic certainty was only reached at two sites. Improved documentation of maternal immunization will be important for vaccine safety studies. Following the field-testing of these 8 GAIA definitions, several improvements are suggested that may lead to their easier implementation, increased standardization and hence comparison across studies.

Feasibility of age- and gestation-based routine universal influenza vaccines schedules for children aged 6 months - 2 years and pregnant women

BACKGROUND

Hong Kong's seasonal influenza schedule follows the World Health Organization's northern hemisphere vaccine composition recommendations but with year-round influenza activity there is the potential to implement routine age- and gestation-based schedules utilising both northern and southern hemisphere vaccines for children aged 6 months to 2 years and for pregnant women. This study assessed the potential feasibility of such schedules.

METHODS

A literature review was conducted and in-depth interviews with vaccine experts, policy makers and nurses were undertaken.

RESULTS

The following schedules were proposed and assessed for perceived feasibility: 1) a four-dose schedule in the first two years of life requiring an additional unscheduled clinic visit at 7 months; 2) a three-dose schedule excluding the 4-week booster after the first dose; 3) a two-dose schedule for pregnant women involving a dose at the booking visit and a dose with pertussis vaccine at 7 months gestation; and 4) a one-dose schedule at 7 months gestation.

CONCLUSIONS

Age- and gestation-based routine influenza vaccination schedules are theoretically feasible for both young children and pregnant women. The three-dose paediatric and one-dose obstetric schedules were assessed in interviews with vaccine experts, policy makers and nurses to be most acceptable. Further clinical studies are required to determine whether such schedules are non-inferior to current seasonal-based schedules in terms of vaccine effectiveness and vaccine uptake.

Transplacental Antibody Transfer of Respiratory Syncytial Virus Specific IgG in Non-Human Primate Mother-Infant Pairs

One approach to protect new-borns against respiratory syncytial virus (RSV) is to vaccinate pregnant women in the last trimester of pregnancy. The boosting of circulating antibodies which can be transferred to the foetus would offer immune protection against the virus and ultimately the disease. Since non-human primates (NHPs) have similar reproductive anatomy, physiology, and antibody architecture and kinetics to humans, we utilized this preclinical species to evaluate maternal immunization (MI) using an RSV F subunit vaccine. Three species of NHPs known for their ability to be infected with human RSV in experimental challenge studies were tested for RSV-specific antibodies. African green monkeys had the highest overall antibody levels of the old-world monkeys evaluated and they gave birth to offspring with anti-RSV titers that were proportional to their mother. These higher overall antibody levels are associated with greater durability found in their offspring. Immunization of RSV seropositive AGMs during late pregnancy boosts RSV titers, which consequentially results in significantly higher titers in the vaccinated new-borns compared to the new-borns of unvaccinated mothers. These findings, accomplished in small treatment group sizes, demonstrate a model that provides an efficient, resource sparing and translatable preclinical in vivo system for evaluating vaccine candidates for maternal immunization.

Chimeric Vaccines Based on Novel Insect-Specific Flaviviruses

Vector-borne flaviviruses are responsible for nearly half a billion human infections worldwide each year, resulting in millions of cases of debilitating and severe diseases and approximately 115,000 deaths. While approved vaccines are available for some of these viruses, the ongoing efficacy, safety and supply of these vaccines are still a significant problem. New technologies that address these issues and ideally allow for the safe and economical manufacture of vaccines in resource-poor countries where flavivirus vaccines are in most demand are urgently required. Preferably a new vaccine platform would be broadly applicable to all flavivirus diseases and provide new candidate vaccines for those diseases not yet covered, as well as the flexibility to rapidly pivot to respond to newly emerged flavivirus diseases. Here, we review studies conducted on novel chimeric vaccines derived from insect-specific flaviviruses that provide a potentially safe and simple system to produce highly effective vaccines against a broad spectrum of flavivirus diseases.

The impact of COVID-19 in pregnancy: Part II. Vaccination to pregnant women

Effective strategies are urgently needed to decrease the risk of untoward outcomes of pregnant women with severe acute respiratory syndrome coronavirus 2 (coronavirus disease 2019 [COVID-19]) infection. Pregnant women are a vulnerable population to infectious disease pandemics with dramatically increased infectious diseases-related serious complications, such as the need of hospitalizations, the need of admission to intensive care unit, and the final disease-related death compared with those nonpregnant counterparts or those pregnant women without infection. Several studies have shown that vaccinations in pregnancy are a safe and highly effective strategy, not only for pregnant women but also for fetus and/or newborn because of the passive transplacental transfer of antibodies to the offspring. Active and passive prevention of infectious diseases is approved as effective strategies for women who attempt to become pregnant or during pregnancy. Despite the large and proven scientific evidence, pregnant women still puzzle over whether they should get vaccinated. The question therefore arises: Why are pregnant women so reluctant to receive vaccination? The explanation is more likely in the way that the benefits of vaccination have been communicated "confusedly." In fact, like virtually all clinical trials, all the COVID-19 vaccine trials have excluded pregnant and lactating women from participating, contributing to uncertainty of safety and efficacy in COVID-19 vaccines that have been well prepared and available for the general adult population worldwide. Moreover, messenger RNA vaccine is a relatively brand-new vaccine, and experience with this type of vaccine is still scarce. It is hard to overcome this innovation deadlock. The knowledge and awareness of pregnant women who are at risk, and full information on the knowledge of vaccines and related preventable diseases in pregnant women may avoid hesitancy and increase vaccine acceptance. The current review is a part two addressing the impact of COVID-19 on pregnant women. We focus on the up-to-date information about the application of vaccination on pregnant women, especially during this COVID-19 pandemic.

Vaccination programs for pregnant women in Europe, 2021

Vaccination during pregnancy is increasingly adopted worldwide in order to protect the mother and her offspring. We studied the current vaccination programs specifically for pregnant women in 42 European countries. Vaccination programs for pregnant women are in place in 37 countries, as follows: influenza (36 countries), pertussis (28), hepatitis B (12), tetanus (10), pneumococcal disease (10), meningococcal disease (10), rabies (8), tick-borne encephalitis (6), hepatitis A (5), poliomyelitis (4), diphtheria (3), Haemophilus influenzae (2), and human papilloma virus (1). Recommendations for vaccination against influenza and pertussis concern almost exclusively pregnant women regardless of high-risk conditions, however differences between vaccination recommendations are noted in terms of timing. Vaccinations against hepatitis B, hepatitis A, pneumococcal disease, meningococcal disease, poliomyelitis, H. influenzae, rabies, and tick-born encephalitis mainly concern pregnant women at high-risk for exposure or serious illness and post-exposure vaccinations. Overall, five European countries have no vaccination recommendations specifically for pregnant women. In conclusion, there are significant differences in vaccination programs for pregnant women in Europe. Vaccination programs for pregnant women should expand in order to protect maternal and infant health. A consensus-based vaccination program is needed.

Attitudes toward Rubella and Varicella Vaccination during Preconception Care

Introduction

Studies of anti-vaccine attitudes in the perinatal time period previously have not paid special attention to the MMR and varicella vaccines. Because both contain live attenuated virus, a contraindication during pregnancy, it is important to assess barriers to vaccination clinically during preconception to avoid the known fetal morbidity associated with congenital rubella or varicella infection.

Methods

The primary outcome of this study was to determine prevalence of patients with nonimmune status for rubella and varicella in the setting of advanced reproductive care. Secondary outcomes of interest included further understanding nonimmune reproductive-aged women's attitudes toward MMR and varicella vaccination during preconception. Patient records with laboratory orders for rubella or varicella immunoglobulin titers, placed at the KU Advanced Reproductive Care clinic between January 2017 and June 2020, were reviewed (n = 2,217). A cross-sectional survey was administered to patients with a laboratory reported negative titer result.

Results

Prevalence of nonimmunity to either rubella or varicella represented 6.0% (n = 134) and 3.8% (n = 85) of records, respectively; nineteen records (0.6%) demonstrated nonimmunity to both. The women who did not receive recommended vaccines following a non-immune titer result (n = 19) most commonly cited their rationale was to not delay fertility treatment further (n = 8), a requirement when receiving live attenuated virus vaccines.

Conclusions

The prevalence of nonimmune persons in the study population fell within the range recognized to be sufficient for herd immunity. The majority of survey respondents indicated that CDC recommended vaccinations were of high personal importance, with strong congruence of thought among those who answered in favor of vaccines when posed with several true or false statements about personal beliefs and vaccine efficacy. The risk/benefit analysis of postponing fertility treatment to achieve adequate levels of immunity should be a focused discussion when establishing fertility treatment goals with patients in the setting of advanced reproductive care.

A retrospective analysis of incident pregnancy in phase 1 and 2a HIV-1 vaccine study participants does not support concern for adverse pregnancy or birth outcomes

Background

Pregnancies occur during HIV-1 vaccine clinical trials, despite requirements for women of reproductive potential to use effective contraception. Deployment of an effective HIV-1 vaccine regimen will likely target adolescents and young adults and therefore safety for pregnant and breastfeeding women will need to be addressed.

Methods

We performed a retrospective, cross-protocol analysis to identify and compare pregnancy outcomes reported in 53 Phase 1 and Phase 2a HIV-1 vaccine clinical trials conducted by the HIV Vaccine Trials Network (HVTN).

Results

Two thousand six hundred seventy-three women of reproductive potential were identified and 193 pregnancies were reported. 39 of 53 (74%) studies had at least one pregnancy reported with an overall pregnancy rate of 3.15 per 100 woman-years (w-yr). While active contraception use was required during study participation, 13 of the 53 studies also contained a long-term follow up period during which pregnancy was no longer discouraged. The pregnancy rate during main study participation was 3.09 per 100 w-yr, while pregnancies occurred at a slightly greater rate in the long-term follow up period (3.22 per 100 w-yr). Adverse pregnancy outcomes were reported at similar rates between vaccinees and placebo recipients when vaccine vectors, adjuvant used, or geographic region were examined.

Conclusion

Although there is considerable heterogeneity amongst the different vaccine trials, there appears to be no obvious indication of increased risk of adverse pregnancy or birth outcomes in these early phase HIV-1 vaccine studies. More complete data on pregnancy outcomes should be collected in early phase HIV-1 vaccine clinical trials to better inform subsequent efficacy trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06431-x.

Methodological frontiers in vaccine safety: qualifying available evidence for rare events, use of distributed data networks to monitor vaccine safety issues, and monitoring the safety of pregnancy interventions

While vaccines are rigorously tested for safety and efficacy in clinical trials, these trials do not include enough subjects to detect rare adverse events, and they generally exclude special populations such as pregnant women. It is therefore necessary to conduct postmarketing vaccine safety assessments using observational data sources. The study of rare events has been enabled in through large linked databases and distributed data networks, in combination with development of case-centred methods. Distributed data networks necessitate common protocols, definitions, data models and analytics and the processes of developing and employing these tools are rapidly evolving. Assessment of vaccine safety in pregnancy is complicated by physiological changes, the challenges of mother-child linkage and the need for long-term infant follow-up. Potential sources of bias including differential access to and utilisation of antenatal care, immortal time bias, seasonal timing of pregnancy and unmeasured determinants of pregnancy outcomes have yet to be fully explored. Available tools for assessment of evidence generated in postmarketing studies may downgrade evidence from observational data and prioritise evidence from randomised controlled trials. However, real-world evidence based on real-world data is increasingly being used for safety assessments, and new tools for evaluating real-world evidence have been developed. The future of vaccine safety surveillance, particularly for rare events and in special populations, comprises the use of big data in single countries as well as in collaborative networks. This move towards the use of real-world data requires continued development of methodologies to generate and assess real world evidence.

Association of Maternal Influenza Vaccination During Pregnancy With Early Childhood Health Outcomes

IMPORTANCE

Seasonal influenza vaccination in pregnancy can reduce influenza illness among pregnant women and newborns. Evidence is limited on whether seasonal influenza vaccination in pregnancy is associated with adverse childhood health outcomes.

OBJECTIVE

To assess the association between maternal influenza vaccination during pregnancy and early childhood health outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study, using a birth registry linked with health administrative data. All live births in Nova Scotia, Canada, between October 1, 2010, and March 31, 2014, were included, with follow-up until March 31, 2016. Adjusted hazard ratios (HRs) and incidence rate ratios (IRRs) with 95% confidence intervals were estimated while controlling for maternal medical history and other potential confounders using inverse probability of treatment weighting.

EXPOSURES

Seasonal influenza vaccination during pregnancy.

MAIN OUTCOMES AND MEASURES

Childhood outcomes studied were immune-related (eg, asthma, infections), non-immune-related (eg, neoplasms, sensory impairment), and nonspecific (eg, urgent or inpatient health care utilization), measured from emergency department and hospitalization databases.

RESULTS

Among 28 255 children (49% female, 92% born at ≥37 weeks' gestation), 10 227 (36.2%) were born to women who received seasonal influenza vaccination during pregnancy. During a mean follow-up of 3.6 years, there was no significant association between maternal influenza vaccination and childhood asthma (incidence rate, 3.0 vs 2.5 per 1000 person-years; difference, 0.53 per 1000 person-years [95% CI, -0.15 to 1.21]; adjusted HR, 1.22 [95% CI, 0.94 to 1.59]), neoplasms (0.32 vs 0.26 per 1000 person-years; difference, 0.06 per 1000 person-years [95% CI, -0.16 to 0.28]; adjusted HR, 1.26 [95% CI, 0.57 to 2.78]), or sensory impairment (0.80 vs 0.97 per 1000 person-years; difference, -0.17 per 1000 person-years [95% CI, -0.54 to 0.21]; adjusted HR, 0.82 [95% CI, 0.49 to 1.37]). Maternal influenza vaccination in pregnancy was not significantly associated with infections in early childhood (incidence rate, 184.6 vs 179.1 per 1000 person-years; difference, 5.44 per 1000 person-years [95% CI, 0.01 to 10.9]; adjusted IRR, 1.07 [95% CI, 0.99 to 1.15]) or with urgent and inpatient health services utilization (511.7 vs 477.8 per 1000 person-years; difference, 33.9 per 1000 person-years [95% CI, 24.9 to 42.9]; adjusted IRR, 1.05 [95% CI, 0.99 to 1.16]).

CONCLUSIONS AND RELEVANCE

In this population-based cohort study with mean follow-up duration of 3.6 years, maternal influenza vaccination during pregnancy was not significantly associated with an increased risk of adverse early childhood health outcomes.

The coronavirus disease 2019 vaccine in pregnancy: risks, benefits, and recommendations

The coronavirus disease 2019 has caused over 2 million deaths worldwide, with over 412,000 deaths reported in Unites States. To date, at least 57,786 pregnant women in the United States have been infected, and 71 pregnant women have died. Although pregnant women are at higher risk of severe coronavirus disease 2019-related illness, clinical trials for the available vaccines excluded pregnant and lactating women. The safety and efficacy of the vaccines for pregnant women, the fetus, and the newborn remain unknown. A review of maternal and neonatal coronavirus disease 2019 morbidity and mortality data along with perinatal vaccine safety considerations are presented to assist providers with shared decision-making regarding vaccine administration for this group, including the healthcare worker who is pregnant, lactating, or considering pregnancy. The coronavirus disease 2019 vaccine should be offered to pregnant women after discussing the lack of safety data, with preferential administration for those at highest risk of severe infection, until safety and efficacy of these novel vaccines are validated.

Barriers and Facilitators Associated With Vaccine Acceptance and Uptake Among Pregnant Women in High Income Countries: A Mini-Review

Vaccination during pregnancy is a safe and effective intervention to protect women from potentially severe consequences of influenza and reduce risk of influenza and pertussis in their infants. However, coverage remains variable. In this mini-review we update findings from a 2015 systematic review to describe results from recent studies in high income countries on the uptake of influenza and pertussis vaccination in pregnancy, reasons for vaccine hesitancy and barriers to increasing uptake, from maternal and healthcare provider (HCP) perspectives. Studies reported highly variable uptake (from 0% to 78%). A main facilitator for uptake among pregnant women was receiving a recommendation from their HCP. However, studies showed that HCP awareness of guidelines did not consistently translate into them recommending vaccines to pregnant women. Safety concerns are a well-established barrier to uptake/coverage of maternal immunization; 7%-52% of unvaccinated women gave safety concerns as a reason but these were also present in vaccinated women. Knowledge/awareness gaps among pregnant women and lack of confidence among HCPs to discuss vaccination were both important barriers. Several studies indicated that midwives were more likely to express safety concerns than other HCPs, and less likely to recommend vaccination to pregnant women. Women who perceived the risk of infection to be low were less likely to accept vaccination in several studies, along with women with prior vaccine refusal. Findings highlight the importance of further research to explore context-specific barriers to vaccination in pregnancy, which may include lack of vaccine confidence among pregnant woman and HCPs, and policy and structural factors.

Vaccination in Pregnancy

BACKGROUND

Vaccination during pregnancy can protect both the expecting mother and the unborn and newborn child from infectious diseases.

METHODS

This review is based on publications retrieved by a selective literature search on the immunological particularities of infectious diseases affecting pregnant women, unborn children, and neonates, with particular attention to the guidelines of the German Standing Committee on Vaccinations (Ständige Impfkommission, STIKO) and the pertinent guidelines.

RESULTS

Vaccination during pregnancy protects the expecting mother from a severe course of a number of different infectious diseases. Vaccination with inactivated vaccines against influenza, tetanus, and pertussis is effective, safe, and well tolerated. Women who are pregnant or of child-bearing age should be immunized against tetanus according to the STIKO recommendations. All pregnant women from the second trimester onward should receive an inactivated quadrivalent influenza vaccine. The immunity acquired after vaccination with an acellular pertussis vaccine is present only for a limited time. In a cohort study involving 72,781 pregnant women, pertussis vaccination during pregnancy was found to yield 91% protection against pertussis for their subsequently born children in the first three months of life. Further types of vaccine can also be given during pregnancy if indicated. Additional reasonable measures to protect the health of mother and child include the vaccination of other persons in close contact as well as the closure of relevant vaccination gaps among young adults, particularly women of child-bearing age. Treating physicians play a crucial role in encouraging vaccine acceptance by their patients.

CONCLUSION

Maternal immunization is a safe and effective strategy for giving neo - nates passive immune protection against life-threatening infections by the vertical transmission of maternal antibodies until they are able to build up their own adaptive immunity.

Uptake of vaccination in pregnancy

Maternal immunisation is a public health strategy that aims to provide protection against certain infections to both mother and her foetus or newborn child. Vaccination of pregnant women induces vaccine-specific antibodies that lead to the subsequent transfer of these antibodies across the placenta or through breastfeeding to the offspring. At present, vaccinations in pregnancy are limited to pertussis, tetanus, diphtheria, polio, and the seasonal Influenza vaccine. Recently, some countries have incorporated routine antenatal vaccinations in their national immunisation programmes. Future vaccines targeted at pregnant women such as respiratory syncytial virus (RSV) and Group B streptococcus (GBS) are under development. The recently approved Covid-19 vaccines have no safety data for use in pregnancy at present, but have been considered in the UK in extremely vulnerable pregnant women or pregnant frontline health and social care workers.

In this article, we review the evidence supporting maternal immunisation and discuss the uptake of vaccines in pregnant women, challenges of recording the data on vaccine coverage, and consider reasons behind the present levels of uptake and strategies for future improvements.

The Costs of Contradictory Messages About Live Vaccines in Pregnancy

The increased risk of harm from COVID-19 infection in pregnancy highlights the importance of including pregnant people in COVID-19 vaccine development and deployment. Promising vaccines being developed include replication-competent platforms, which are typically contraindicated during pregnancy because of theoretical risk. However, replicating vaccines are administered in and around pregnancy, either inadvertently because of unknown pregnancy status or when recommended.The historical cases of Ebola virus, yellow fever, and rubella demonstrate that contradictory messages around the safety of live vaccines in pregnancy have critical public health costs. First, restricting study or use of replicating vaccines in pregnancy may delay or deny access to the only available protection against deadly diseases. Additionally, not vaccinating pregnant people may slow epidemic control. Finally, uncertainty and worry around the safety of live vaccines may lead to terminations of otherwise desired pregnancies after inadvertent vaccination in pregnancy.If one of the vaccines deployed to combat the current global COVID-19 pandemic is replication competent, historical cases offer important lessons for ethical and effective protection for pregnant populations.

Vaccination of pregnant women against influenza: what is the optimal timing?

Pregnant women and young infants are at increased risk for severe influenza and its complications. Influenza vaccination during pregnancy is increasingly implemented as a strategy aiming to protect the pregnant woman, the fetus and the young infant. In clinical practice, the achievement of satisfactory protection for the pregnant woman without compromising the protection of her infant during the first months of life remains a challenge. Determinants that are implicated in the optimal timing of influenza vaccination in pregnancy include influenza season, trimester of pregnancy, maternal host factors and infant factors. This article addresses influenza vaccination in pregnancy and presents recent published evidence on issues that affect the optimization of the timing of maternal vaccination.

A genetically stable Zika virus vaccine candidate protects mice against virus infection and vertical transmission

Although live attenuated vaccines (LAVs) have been effective in the control of flavivirus infections, to date they have been excluded from Zika virus (ZIKV) vaccine trials due to safety concerns. We have previously reported two ZIKV mutants, each of which has a single substitution in either envelope (E) glycosylation or nonstructural (NS) 4B P36 and displays a modest reduction in mouse neurovirulence and neuroinvasiveness, respectively. Here, we generated a ZIKV mutant, ZE4B-36, which combines mutations in both E glycosylation and NS4B P36. The ZE4B-36 mutant is stable and attenuated in viral replication. Next-generation sequence analysis showed that the attenuating mutations in the E and NS4B proteins are retained during serial cell culture passages. The mutant exhibits a significant reduction in neuroinvasiveness and neurovirulence and low infectivity in mosquitoes. It induces robust ZIKV-specific memory B cell, antibody, and T cell-mediated immune responses in type I interferon receptor (IFNR) deficient mice. ZIKV-specific T cell immunity remains strong months post-vaccination in wild-type C57BL/6 (B6) mice. Vaccination with ZE4B-36 protects mice from ZIKV-induced diseases and vertical transmission. Our results suggest that combination mutations in E glycosylation and NS4B P36 contribute to a candidate LAV with significantly increased safety but retain strong immunogenicity for prevention and control of ZIKV infection.

Immune Regulation, Maternal Infection, Vaccination, and Pregnancy Outcome

About 12.5% of all maternal deaths in the United States are due to infectious causes. This proportion, although stable during the past three decades, represents an increase in infectious causes of mortality, as the overall mortality rate in U.S. pregnant women had increased steadily during that same period. During healthy pregnancies, a delicate immunological balance-in which a mother's immune system tolerates the semi-allogeneic fetus yet maintains immune competency against infectious agents-is achieved and maintained. This immunological paradigm, however, results in increased susceptibility to infectious diseases during pregnancy, particularly in later stages and during the early postpartum period. The inflammatory process induced by these infectious insults, as well as some noninfectious insults, occurring during pregnancy can disrupt this carefully achieved balance and, in turn, lead to a state of rampant inflammation, immune activation, and dysregulation with deleterious health outcomes for the mother and fetus. Elucidating mechanisms contributing to the disruption of this immunologic homeostasis, and its disruption by infectious pathogens, might offer opportunities for interventions to reduce maternal and fetal morbidity and mortality.

Study of the teratogenicity of the vaccine strain of the Rubella virus «Orlov-V» (Matonaviridae: Rubivirus: Rubella virus) in experience on rhesus macaques

INTRODUCTION

Rubella virus has pronounced teratogenic properties that can cause generalized and persistent intrauterine infection of the fetus. As a result, the control of the loss of teratogenicity inherent in «wild-type» virus strains is a necessary stage of a preclinical study of the vaccine strain for a live attenuated rubella vaccine.The purpose of the study is to comprehensively study the teratogenic properties of the vaccine strain of rubella virus «Orlov-V» in the experiment on rhesus macaques.

MATERIAL AND METHODS

Seronegative to rubella virus female rhesus macaques in early pregnancy at the age of 4-7 years (n = 13) were used in the experiment. Animals of the experimental group (n = 9) received single immunization intramuscularly with a preparation from the «Orlov-V» strain. The control group of the monkeys (n = 3) were immunized with a commercial vaccine containing Wistar RA27/3 strain. The female of the control group (n = 1) was injected with a solvent used in the rubella vaccine. Study of possible teratogenic properties of vaccine strains of rubella virus was carried out using a complex of clinical, immunological, pathomorphological and virological methods. Clinical observations were made within 3 months after the monkeys' birth. Determination of antibody titers in the blood serum of immunized monkeys was performed in HI test on the 28th-30th day after infection. The ELISA method was applied to determine IgM antibodies in the blood serum of newborns within the first month of life. Detection of rubella virus RNA was performed by PCR with electrophoretic detection of amplicons.

RESULTS

No markers of congenital rubella infection were found in infants born from monkeys vaccinated during the pregnancy. It is shown that PCR can be an informative method to confirm the absence of teratogenic properties of vaccine strains of rubella virus.

DISCUSSION

The obtained data demonstrated that vaccine strains of the «Orlov-V» rubella virus and Wistar RA27/3 have lost their teratogenic properties. The possibility of using an alternative strategy for preclinical assessment of specific safety of antiviral vaccines including a complex of clinical, immunological, pathologic and virological methods instead of the classical pathologic method is discussed.

CONCLUSION

The results obtained in this study showed the absence of teratogenic properties and high immunogenic activity of the vaccine strain of rubella virus «Orlov-V».

The Protective Role of Maternal Immunization in Early Life

With birth, the newborn is transferred from a quasi-sterile environment to the outside world. At this time, the neonatal immune system is inexperienced and continuously subject to a process of development as it encounters different antigenic stimuli after birth. It is initially characterized by a bias toward T helper 2 phenotype, reduced T helper 1, and cytotoxic responses to microbial stimuli, low levels of memory, and effector T and B cells and a high production of suppressive T regulatory cells. The aim of this setting, during fetal life, is to maintain an anti-inflammatory state and immune-tolerance. Maternal antibodies are transferred during pregnancy through the placenta and, in the first weeks of life of the newborn, they represent a powerful tool for protection. Thus, optimization of vaccination in pregnancy represents an important strategy to reduce the burden of neonatal infections and sepsis. Beneficial effects of maternal immunization are universally recognized, although the optimal timing of vaccination in pregnancy remains to be defined. Interestingly, the dynamic exchange that takes place at the fetal-maternal interface allows the transfer not only of antibodies, but also of maternal antigen presenting cells, probably in order to stimulate the developing fetal immune system in a harmless way. There are still controversial effects related to maternal immunization including the so called "immunology blunting," i.e., a dampened antibody production following infant's vaccination in those infants who received placentally transferred maternal immunity. However, clinical relevance of this phenomenon is still not clear. This review will provide an overview of the evolution of the immune system in early life and discuss the benefits of maternal vaccination. Current maternal vaccination policies and their rationale will be summarized on the road to promising approaches to enhance immunity in the neonate.

Maternal immunization country readiness: a checklist approach

Prior to the addition of a maternal vaccine onto the National Immunization Programme, it is important for a country to evaluate their capacity and readiness. This checklist has been developed that is deliberately not restricted to any particular vaccine so it can be applied by national-level stakeholders during the decision-making stage for the introduction of any additional or new maternal vaccine. It is suggested that a team consisting of representatives from the Ministry of Health, including the National Immunization Programme (NIP) and Maternal, Newborn and Child Health (MNCH) programs complete and review the checklist together. This checklist enables countries to assess their capacity, strengths and weaknesses and identify a list of priorities to allow for smooth implementation of maternal vaccines.

Ocular coloboma combined with cleft lip and palate: a case report

Background

Ocular coloboma is an excavation of ocular structures that occurs due to abnormal fusion of the embryonic optic fissure. Further, cleft lip/palate (CL/P), a congenital midline abnormality, is caused by a defect in the fusion of the frontonasal, maxillary, and mandibular prominences. No study has reported the association between these two phenotypes in the absence of other systemic abnormalities. We present a case of ocular coloboma along with CL/P and without other neurological abnormalities.

Case presentation

A 5-year-old Asian boy presented with decreased visual acuity in his right eye. Physical examination revealed no abnormal findings except CL/P, which was surgically corrected at the age of 9 months. Best-corrected visual acuity was 20/60 in the right eye and 20/25 in the left eye. Anterior segment examination revealed iris coloboma in the inferior quadrant of his right eye as well as a large inferonasal optic disc and chorioretinal coloboma in the same eye. He was prescribed glasses based on his cycloplegic refractive errors and part-time occlusion of the left eye was recommended. After 3 months, best-corrected visual acuity improved to 20/30 in the right eye.

Conclusion

The association of ocular coloboma should be kept in mind when encountering a patient with CL/P without other neurological or systemic abnormalities.

Pregnant women's perceptions of risks and benefits when considering participation in vaccine trials

INTRODUCTION

Despite historical exclusion, there has been recent recognition of the need to address the health of pregnant women in research on vaccines against emerging pathogens. However, pregnant women's views and decision-making processes about vaccine research participation during infectious disease outbreaks remain underexplored. This study aims to examine women's decision-making processes around vaccine research participation during infectious disease outbreaks.

METHODS

We conducted qualitative semi-structured in-depth interviews with pregnant and recently pregnant women (n = 13), eliciting their views on four hypothetical Zika Virus vaccine research scenarios and probing their decision-making processes around participation. After recorded interviews were transcribed, thematic analysis was conducted based on a priori and emergent themes.

RESULTS

Most women interviewed were accepting of vaccine research scenarios. Three broad themes-evidence, risk, and trust-characterized women's decision-making processes. Women varied in how different types and levels of evidence impacted their considerations, which risks were most salient to their decision-making processes, and from whom they trusted recommendations about vaccine research participation. Exemplary quotes from each theme are presented, and lessons for vaccine development during the current COVID-19 pandemic and future outbreaks are discussed.

CONCLUSION

Some pregnant women are accepting of participation in vaccine research during infectious disease outbreaks. Incorporating their priorities into trial design may facilitate their participation and generation of evidence for this important population.