Guideline for collection, analysis and presentation of safety data in clinical trials of vaccines in pregnant women

Infant Responses to Primary Immunization Following Vaccination in Pregnancy With Varying Doses of Recombinant Acellular Pertussis Vaccine Alone or Combined With Tetanus-Diphtheria

BACKGROUND

Vaccination in pregnancy with recombinant pertussis vaccine results in similar or higher antibody levels in infants compared with chemically detoxified acellular pertussis vaccine (Tdapchem). We evaluated antibody responses to primary childhood vaccination in infants born to mothers vaccinated in pregnancy with recombinant pertussis vaccine containing 1, 2 or 5 µg genetically detoxified pertussis toxin (ap1gen, Tdap1gen, Tdap2gen or TdaP5gen) or Tdapchem.

METHODS

Infants (393) received diphtheria-tetanus-whole cell pertussis (DTwP) at 2, 4 and 6 months (3+0) and 13-valent pneumococcal conjugate vaccine (PCV13) at 2, 4 and 12 months of age (2+1). Serum IgG levels against pertussis toxoid (PT), filamentous hemagglutinin (FHA), diphtheria toxoid (DT), tetanus toxoid (TT), PCV13 serotypes and PT-neutralizing antibody (PT-Nab) titers were assessed. PT-IgG ≥10 IU was used as a cutoff for potential protection in infants.

RESULTS

PT-IgG geometric mean concentrations (GMC) were ≥10 IU/mL at 5 and 7 months of age but waned below 10 IU/mL at 13 months in all groups. FHA-IgG GMCs and PT-Nab geometric mean titers were also below 10 IU/mL in all groups at 13 months of age. TT-IgG and DT-IgG seroprotection rates (≥0.1 IU/mL) ranged from 97.1% to 100% at 7 and 13 months. Postbooster PCV13-serotype-specific seroprotection rates (IgG ≥ 0.35 µg/mL) ranged between 87% and 100%. Antibody responses were comparable between groups after DTwP priming (7 months) and PCV13 priming (5 months) and booster vaccination (13 months).

CONCLUSIONS

Childhood vaccine responses are comparable after mothers receive genetically or chemically detoxified acellular pertussis vaccines in pregnancy.

Protecting mother and baby: Learnings from an Ebola vaccination campaign on the evolving landscape of vaccines and pregnancy

This Perspective article from Rebecca Grais and colleagues places a recently published study in PLOS Medicine in the context of the evolving landscape of vaccines and pregnancy.

Obstetric and neonatal outcomes in South Africa

BACKGROUND

Background epidemiologic population data from low- and middle-income countries (LMIC), on maternal, foetal and neonatal adverse outcomes are limited. We aimed to estimate the incidence of maternal, foetal and neonatal adverse outcomes at South African maternal vaccine trial sites as reported directly in the clinical notes as well as using the 'Global Alignment of Immunization Safety Assessment in Pregnancy' case definitions (GAIA-CDs). GAIA-CDs were utilized as a tool to standardise data collection and outcome assessment, and the applicability and utility of the GAIA-CDs was evaluated in a LMIC observational study.

METHODS

We conducted a retrospective record review of maternity and neonatal case records for births that occurred in Soweto, Inner City- Johannesburg and Metro-East Cape Town, South Africa, between 1st July 2017 and 30th June 2018. Study staff abstracted data from randomly selected medical charts onto standardized study-specific forms. Incidence (per 100,000 population) was calculated for adverse maternal, foetal and neonatal outcomes, which were identified as priority outcomes in vaccine safety studies by the Brighton Collaboration and World Health Organization. Outcomes reported directly in the clinical notes and outcomes which fulfilled GAIA-CDs were compared. Incidence of outcomes was calculated by combining cases which were either reported in clinical notes by attending physicians and/ or fulfilled GAIA-CDs.

FINDINGS

Of 9371 pregnant women enrolled, 27·6% were HIV-infected, 19·9% attended antenatal clinic in the 1st trimester of pregnancy and 55·3% had ≥1 ultrasound examination. Fourteen percent of women had hypertensive disease of pregnancy, 1·3% had gestational diabetes mellitus and 16% experienced preterm labour. There were 150 stillbirths (1·6%), 26·8% of infants were preterm and five percent had microcephaly. Data available in clinical notes for some adverse outcomes, including maternal- & neonatal death, severe pre-eclampsia/ eclampsia, were able to fulfil GAIA-CDs criteria for all of the clinically-reported cases, however, missing data required to fulfil other GAIA-CD criteria (including stillbirth, gestational diabetes mellitus and gestational hypertension) led to poor correlation between clinically-reported adverse outcomes and outcomes fulfilling GAIA-CDs. Challenges were also encountered in accurately ascertaining gestational age.

INTERPRETATION

This study contributes to the expanding body of data on background rates of adverse maternal and foetal/ neonatal outcomes in LMICs. Utilization of GAIA-CDs assists with alignment of data, however, some GAIA-CDs require amendment to improve the applicability in LMICs.

FUNDING

This study was funded by Pfizer (Inc).

Effective and safe transfer of maternal antibodies persisting two months postpartum following maternal immunization with different doses of recombinant pertussis-containing vaccines

INTRODUCTION

Recombinant acellular pertussis (ap) vaccines containing genetically inactivated pertussis toxin (PTgen) and filamentous hemagglutinin (FHA) with or without tetanus (TT) and diphtheria (DT) vaccines (Td) were found safe and immunogenic in non-pregnant and pregnant women. We report here maternal antibody transfer and safety data in mothers and neonates.

METHODS

This is the follow up of a phase 2 trial in 2019 among 400 pregnant women who randomly received one dose of recombinant pertussis-only vaccine containing 1 µg PTgen and 1 µg FHA (ap1gen), or Td combined with ap1gen (Tdap1gen), or with 2 µg PTgen and 5 µg FHA (Tdap2gen), or with 5 µg PTgen and 5 µg FHA (TdaP5gen, Boostagen®, BioNet, Thailand) or chemically-inactivated acellular pertussis comparator (Tdap8chem, Boostrix™, GSK, Belgium), either in the second or third trimester of gestation. IgG against PT, FHA, TT and DT were assessed by ELISA, PT-neutralizing antibodies (PTNA) by Chinese Hamster Ovary cell assay and safety outcomes at delivery in mothers and at birth.

RESULTS

Anti-PT and anti-FHA geometric mean concentration (GMC) ratio between infants at birth and mothers at delivery was above 1 in all groups. PT GMC in infants at birth were ≥30 IU/mL in all groups with the highest titers in infants found in TdaP5gen group at birth (118.8 [95% CI 93.9-150.4]). At 2 months, PT GMC ratio to Tdap8chem (98.75% CI) was significantly higher for TdaP5gen (2.6 [1.7-4.0]) and comparable for other recombinant vaccines. No difference in PTNA titers at birth was observed between all groups nor between time of vaccination. Adverse events were comparable in all vaccine groups.

CONCLUSIONS

BioNet licensed (TdaP5gen and Tdap2gen) and candidate vaccines (Tdap1gen and ap1gen) when given to pregnant women in the second or third trimester of gestation are safe and have induced passive pertussis immunity to infants.

Exclusion of pregnant people from emergency vaccine clinical trials: A systematic review of clinical trial protocols and reporting from 2009 to 2019

BACKGROUND

Existing ethics guidance and regulatory requirements emphasize the need for pregnancy-specific safety and efficacy data during the development of vaccines in health emergencies. Our objective was to conduct a systematic review of vaccine clinical trials during active epidemic periods.

METHODS

We searched for Phase II and Phase III vaccine clinical trials initiated during the H1N1 influenza, Middle East Respiratory Syndrome Coronavirus (MERS-CoV), Zika, and Ebola virus disease (EVD) outbreaks from 2009 to 2019. Data were extracted from clinical trial protocols identified in the following registries: ClinicalTrials.gov, Pan African Clinical Trial Registry (PACTR), and all primary registries indicated by the World Health Organization's International Clinical Trials Registry Platform (ICTRP). Published studies from registered clinical trials were located through PubMed. Data was extracted on eligibility criteria and pregnancy outcomes. Data from this study is available in the Center for Open Science Data Repository: https://osf.io/nfk2p/?view_only=47deb3b206724af9b46c9c0c0083a267.

RESULTS

We identified 96 vaccine clinical trial protocols and included 84 in analysis. 5 records were excluded in screening for irrelevant abstracts, 7 were excluded in full-text assessment (1 for a therapeutic drug trial, 3 for enrolling elderly adults only, 3 for enrolling children/adolescents only). There were no eligible trials for MERS-CoV or Zika virus vaccines. Overall, 8 protocols explicitly included pregnant people; of these, 3 were completed trials with published results. Incidental pregnancies and outcomes of pregnant participants were reported in 2 studies, 10 studies reported serious adverse events related to pregnancy without mentioning total incidental pregnancies. A total of 411 recorded pregnancy outcomes were reported, with 293 from the 3 pregnancy-eligible studies with results. 71 serious adverse events pertaining to pregnancy were reported from all clinical trials with results.

CONCLUSION

Pregnant people are underrepresented in vaccine clinical trials conducted during outbreaks, resulting in underreporting of pregnancy-related outcomes and a lack of protection for pregnant people and neonates from infectious diseases.

Data collection systems for active safety surveillance of vaccines during pregnancy in low- and middle-income countries: developing and piloting an assessment tool (VPASS)

BACKGROUND

There is an urgent need for active safety surveillance to monitor vaccine exposure during pregnancy in low- and middle-income countries (LMICs). Existing maternal, newborn, and child health (MNCH) data collection systems could serve as platforms for post-marketing active surveillance of maternal immunization safety. To identify sites using existing systems, a thorough assessment should be conducted. Therefore, this study had the objectives to first develop an assessment tool and then to pilot this tool in sites using MNCH data collection systems through virtual informant interviews.

METHODS

We conducted a rapid review of the literature to identify frameworks on population health or post-marketing drug surveillance. Four frameworks that met the eligibility criteria were identified and served to develop an assessment tool capable of evaluating sites that could support active monitoring of vaccine safety during pregnancy. We conducted semi-structured interviews in six geographical sites using MNCH data collection systems (DHIS2, INDEPTH, and GNMNHR) to pilot domains included in the assessment tool.

RESULTS

We developed and piloted the "VPASS (Vaccines during Pregnancy - sites supporting Active Safety Surveillance) assessment tool" through interviews with nine stakeholders, including central-level systems key informants and site-level managers from DHIS2 and GNMNHR; DHIS2 in Kampala (Uganda) and Kigali (Rwanda); GNMNHR from Belagavi (India) and Lusaka (Zambia); and INDEPTH from Nanoro (Burkina Faso) and Manhica (Mozambique). The tool includes different domains such as the system's purpose, the scale of implementation, data capture and confidentiality, type of data collected, the capability of integration with other platforms, data management policies and data quality monitoring. Similarities among sites were found regarding some domains, such as data confidentiality, data management policies, and data quality monitoring. Four of the six sites met some domains to be eligible as potential sites for active surveillance of vaccinations during pregnancy, such as a routine collection of MNCH individual data and the capability of electronically integrating individual MNCH outcomes with information related to vaccine exposure during pregnancy. Those sites were: Rwanda (DHIS2), Manhica (IN-DEPTH), Lusaka (GNMNHR), and Belagavi (GNMNHR).

CONCLUSION

This study's findings should inform the successful implementation of active safety surveillance of vaccines during pregnancy by identifying and using active individual MNCH data collection systems in LMICs.

The COVID-19 Vaccines International Pregnancy Exposure Registry (C-VIPER): Protocol and Methodological Considerations

INTRODUCTION

The advent of the coronavirus disease 2019 (COVID-19) pandemic has led to the development of vaccines against severe acute respiratory syndrome coronavirus 2. Prospective evidence regarding safety for pregnant people and their developing fetuses is lacking. The aim of the COVID-19 Vaccines International Pregnancy Exposure Registry (C-VIPER) is to estimate the relative risk of obstetric, neonatal, and infant outcomes by comparing participants vaccinated against COVID-19 during pregnancy to a reference group of people enrolled in the Pregistry International Pregnancy Exposure Registry (PIPER) who remained unvaccinated during pregnancy.

METHODS

The C-VIPER and the PIPER are international, non-interventional, real-world cohort studies. Participants receiving a COVID-19 vaccine during pregnancy will be matched in the analyses by country and gestational age at enrollment to unvaccinated individuals. Self-enrolled and self-consented participants complete online questionnaires at enrollment, during pregnancy, and for 12 months after the delivery of a live infant. Where possible, outcomes are verified by medical records. The study aims to recruit at least 500 pregnancies for each approved or authorized vaccine and will last for 5 years for each product.

CONCLUSIONS

By collecting data for each vaccine brand, the C-VIPER will be able to determine individual safety profiles. The study design allows for analysis of the effects of exposure to COVID-19 vaccines during specific etiologically relevant periods of gestation. Although the sample size may be too small to detect associations with rare outcomes, the study will be used to generate hypotheses for future research. Ultimately, the C-VIPER should provide data that will allow pregnant people and their healthcare providers to make informed decisions about COVID-19 vaccination.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT04705116. Registered on 12 January, 2021. EU PAS EUPAS39096. Registered on 20 January, 2021.

Preparing for Disease X: Ensuring Vaccine Equity for Pregnant Women in Future Pandemics

Disease X represents a yet unknown human pathogen which has potential to cause a serious international epidemic or pandemic. The COVID-19 pandemic has illustrated that despite being at increased risk of severe disease compared with the general population, pregnant women were left behind in the development and implementation of vaccination, resulting in conflicting communications and changing guidance about vaccine receipt in pregnancy. Based on the COVID-19 experience, the COVAX Maternal Immunization Working Group have identified three key factors and five broad focus topics for consideration when proactively planning for a disease X pandemic, including 10 criteria for evaluating pandemic vaccines for potential use in pregnant women. Prior to any disease X pandemic, collaboration and coordination are needed to close the pregnancy data gap which is currently a barrier to gender equity in health innovation, which will aid in allowing timely access to life-saving interventions including vaccines for pregnant women and their infants.

Validating Claims-Based Algorithms Determining Pregnancy Outcomes and Gestational Age Using a Linked Claims-Electronic Medical Record Database

INTRODUCTION

Pregnancy outcome identification and precise estimates of gestational age (GA) are critical in drug safety studies of pregnant women. Validated pregnancy outcome algorithms based on the International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS) have not previously been published.

METHODS

We developed algorithms to classify pregnancy outcomes and estimate GA using ICD-10-CM/PCS and service codes on claims in the 2016-2018 IBM® MarketScan® Explorys® Claims-EMR Data Set and compared the results with ob-gyn adjudication of electronic medical records (EMRs). Obstetric services were grouped into episodes using hierarchical and spacing requirements. GA was based on evidence with the highest clinical accuracy. Among pregnancies with obstetric EMRs, 100 full-term live births (FTBs), 100 preterm live births (PTBs), 100 spontaneous abortions (SAs), and 24 stillbirths were selected for review. Physicians adjudicated cases using Global Alignment of Immunization safety Assessment in pregnancy (GAIA) definitions applied to structured EMRs.

RESULTS

The claims-based algorithms identified 34,204 pregnancies, of which 9.9% had obstetric EMRs. Of sampled pregnancies, 92 FTBs, 93 PTBs, 75 SAs, and 24 stillbirths were adjudicated. Among these pregnancies, the percent agreement was 97.8%, 62.4%, 100.0%, and 70.8% for FTBs, PTBs, SAs, and stillbirths, respectively. The percent agreement on GA within 7 and 28 days, respectively, was 85.9% and 100.0% for FTBs, 81.7% and 98.9% for PTBs, 61.3% and 94.7% for SAs, and 66.7% and 79.2% for stillbirths.

CONCLUSIONS

The pregnancy outcome algorithms had high agreement with physician adjudication of EMRs and may inform post-market maternal safety surveillance.

A reasoned approach towards administering COVID-19 vaccines to pregnant women

There are over 50 SARS-CoV-2 candidate vaccines undergoing Phase II and III clinical trials. Several vaccines have been approved by regulatory authorities and rolled out for use in different countries. Due to concerns of potential teratogenicity or adverse effect on maternal physiology, pregnancy has been a specific exclusion criterion for most vaccine trials with only two trials not excluding pregnant women. Thus, other than limited animal studies, gradually emerging development and reproductive toxicity data, and observational data from vaccine registries, there is a paucity of reliable information to guide recommendations for the safe vaccination of pregnant women. Pregnancy is a risk factor for severe COVID-19, especially in women with comorbidities, resulting in increased rates of preterm birth and maternal morbidity. We discuss the major SARS-CoV-2 vaccines, their mechanisms of action, efficacy, safety profile and possible benefits to the maternal-fetal dyad to create a rational approach towards maternal vaccination while anticipating and mitigating vaccine-related complications. Pregnant women with high exposure risks or co-morbidities predisposing to severe COVID-19 infection should be prioritised for vaccination. Those with risk factors for adverse effects should be counselled accordingly. It is essential to support patient autonomy by shared decision-making involving a risk-benefit discussion with the pregnant woman.

Optimising the Timing of whooping cough Immunisation in MUMs: a randomised controlled trial investigating the timing of pertussis vaccination in pregnancy (OpTIMUM): a protocol paper

Background: Pertussis is a highly infectious respiratory illness caused by the bacteria Bordetella pertussis. A resurgence of pertussis, even in countries with good vaccine coverage, has led to an increase in infant deaths. In response to this, many countries have introduced pertussis vaccination in pregnancy. This strategy is effective at preventing infant disease, but there remains uncertainty about what gestational timing is best to ensure maximal protection of the infant. These uncertainties are the rationale for this randomised controlled trial and a sub-study investigating pertussis-specific antibody in breastmilk.   Protocol: We will recruit 354 pregnant women and will randomise them to receive their pertussis vaccination in one of three gestational age windows: ≤23+6, 24-27+6 and 28-31+6 weeks of gestation.  Vaccination will be with Boostrix-IPV® and participants will be asked to complete a symptom diary for seven days following vaccination. Blood sampling will be performed prior to vaccination, two weeks following vaccination and at the time of delivery. A cord blood sample will be collected at delivery and a blood sample collected from the infant 4-10 weeks after completion of the primary immunisations. Individuals participating in the breastmilk sub-study will provide a sample of colostrum within 48 hours of delivery and samples of breastmilk at two weeks and around five-six months. Blood samples will be analysed using enzyme linked immunosorbent assay (ELISA) techniques for pertussis toxin, filamentous haemagglutinin and pertactin. A subset of serum samples will also be analysed using a functional assay. Colostrum and breastmilk samples will be analysed using functional assays. Discussion: Although pertussis vaccination has been shown to be safe and effective in pregnancy there remains debate about the optimal timing for the administration during pregnancy. This study will investigate antibody responses in serum and breastmilk when vaccination is performed in three different time periods. Clinicaltrials.gov registration: NCT03908164 (09/04/2019)

Maternal and neonatal data collection systems in low- and middle-income countries for maternal vaccines active safety surveillance systems: A scoping review

BACKGROUND

Most post-licensure vaccine pharmacovigilance in low- and middle-income countries (LMICs) are passive reporting systems. These have limited utility for maternal immunization pharmacovigilance in LMIC settings and need to be supplemented with active surveillance. Our study's main objective was to identify existing perinatal data collection systems in LMICs that collect individual information on maternal and neonatal health outcomes and could be developed to inform active safety surveillance of novel vaccines for use during pregnancy.

METHODS

A scoping review was performed following the Arksey and O'Malley six-stage approach. We included studies describing electronic or mixed paper-electronic data collection systems in LMICs, including research networks, electronic medical records, and custom software platforms for health information systems. Medline PubMed, EMBASE, Global Health, Cochrane Library, LILACS, Bibliography of Asian Studies (BAS), and CINAHL were searched through August 2019. We also searched grey literature including through Google and websites of existing relevant perinatal data collection systems, as well as contacted authors of key studies and experts in the field to validate the information and identify additional sources of relevant unpublished information.

RESULTS

A total of 11,817 records were identified. The full texts of 264 records describing 96 data collection systems were assessed for eligibility. Eight perinatal data collection systems met our inclusion criteria: Global Network's Maternal Newborn Health Registry, International Network for the Demographic Evaluation of Populations and their Health; Perinatal Informatic System; Pregnancy Exposure Registry & Birth Defects Surveillance; SmartCare; Open Medical Record System; Open Smart Register Platform and District Health Information Software 2. These selected systems were qualitatively characterized according to seven different domains: governance; system design; system management; data management; data sources, outcomes and data quality.

CONCLUSION

This review provides a list of active maternal and neonatal data collection systems in LMICs and their characteristics as well as their outreach, strengths, and limitations. Findings could potentially help further understand where to obtain population-based high-quality information on outcomes to inform the conduct of maternal immunization active vaccine safety surveillance activities and research in LMICs.

"Vaccines for pregnant women…?! Absurd" - Mapping maternal vaccination discourse and stance on social media over six months

OBJECTIVE

To understand the predominant topics of discussion, stance and associated language used on social media platforms relating to maternal vaccines in 15 countries over a six-month period.

BACKGROUND

In 2019, the World Health Organisation prioritised vaccine hesitancy as a top ten global health threat and recognized the role of viral misinformation on social media as propagating vaccine hesitancy. Maternal vaccination offers the potential to improve maternal and child health, and to reduce the risk of severe morbidity and mortality in pregnancy. Understanding the topics of discussion, stance and language used around maternal vaccines on social media can inform public health bodies on how to combat vaccine misinformation and vaccine hesitancy.

METHODS

Social media data was extracted (Twitter, forums, blogs and comments) for six months from 15 countries (Australia, Brazil, Canada, France, Germany, India, Italy, Korea, Mexico, Panama, South Africa, Spain, United Kingdom and United States). We used stance, discourse and topic analysis to provide insight into the most frequent and weighted keywords, hashtags and themes of conversation within and across countries.

RESULTS

We exported a total of 19,192 social media posts in 16 languages obtained between 1st November 2018 and 30th April 2019. After screening all posts, 16,000 were included in analyses, while excluding retweets, 2,722 were annotated for sentiment. Main topics of discussion were the safety of the maternal influenza and pertussis vaccines. Discouraging posts were most common in Italy (44.9%), and the USA (30.8%).

CONCLUSION

The content and stance of maternal vaccination posts from November 2018 to April 2019 differed across countries, however specific topics of discussion were not limited to geographical location. These discussions included the promotion of vaccination, involvement of pregnant women in vaccine research, and the trust and transparency of institutions. Future research should examine the relationship between stance (promotional, neutral, ambiguous, discouraging) online and maternal vaccination uptake in the respective regions.

Pregnancy outcomes after a mass vaccination campaign with an oral cholera vaccine: a systematic review and meta-analysis

BACKGROUND

Cholera has harmful effects on the fetus but safety data on the oral cholera vaccine in pregnant women are controversial.

OBJECTIVES

We conducted the first meta-analysis of studies in pregnant women comparing the effect of oral cholera vaccination on pregnancy outcomes with unvaccinated women. Outcomes of interest were adverse pregnancy outcome, miscarriage, stillbirth, preterm delivery, low birthweight, abortion and malformation.

SEARCH STRATEGY

The search was run in MEDLINE/PubMed, SCOPUS and Embase databases from inception up to December 2019.

SELECTION CRITERIA

Inclusion criteria were: (1) studies that investigated the association between oral cholera vaccines and adverse pregnancy outcomes; (2) studies that reported outcomes with appropriate estimates; and (3) studies that contained an unvaccinated control group.

DATA COLLECTION AND ANALYSIS

A random-effects model (DerSimonian and Laird) was run to evaluate the overall treatment effect (relative risk, RR). The PRISMA statement was followed in reporting this meta-analysis.

MAIN RESULTS

Five studies included in meta-analysis with 5584 women (2920 exposed and 2664 not exposed). No significant increase in adverse pregnancy outcome (RR 1.03, 95% CI 0.79-1.34), miscarriage (RR 1.15, 95% CI 0.84-1.57) or stillbirth (RR 1.11, 95% CI 0.69-1.80) following cholera vaccine administration was found compared with control group. There was also no association with an increased risk of preterm delivery (RR 0.61, 95% CI 0.35-1.06) low birthweight (RR 0.84, 95% CI 0.56- 1.26), accidental abortion (RR 1.02, 95% CI 0.77-1.35) or malformation (RR 0.70, 95% CI 0.22-2.25).

CONCLUSIONS

This study shows no evidence of an association between oral cholera vaccination and adverse pregnancy outcomes. The findings do not rigorously exclude the possibility that the vaccine protocol may result in some degree of harm.

TWEETABLE ABSTRACT

There is no evidence of an association between oral cholera vaccination and adverse pregnancy outcomes. The findings do not rigorously exclude the possibility that the vaccine protocol may result in some degree of harm.

Obstetrics risk Assessment: Evaluation of selection criteria for vaccine research studies in pregnant women

Vaccines designed for use in pregnancy and vaccine trials specifically involving pregnant women are rapidly expanding. One of the key challenges in designing maternal immunization trials is that developing exclusion criteria requires understanding and quantifying the background risk for adverse pregnancy outcomes in the pregnancy being studied, which can occur independent of any intervention and be unrelated to vaccine administration. The Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) project has developed and published case definitions and guidelines for data collection, analysis, and evaluation of maternal immunization safety in trials involving pregnant women. Complementing this work, we sought to understand how to best assess obstetric risk of adverse outcomes and differentiate it from the assessment of vaccine safety. Quantification of obstetric risk is based on prior and current obstetric, and maternal medical history. We developed a step-wise approach to evaluate and quantify obstetric and maternal risk factors in pregnancy based on review of published literature and guidelines, and critically assessed these factors in the context of designing inclusion and exclusion criteria for maternal vaccine studies. We anticipate this risk assessment evaluation may assist clinical trialists with study design decisions, including selection of exclusion criteria for vaccine trials involving pregnant women, consideration of sub-group classification, such as high or low risk subjects, or schedule considerations, such as preferred trimester of gestation for an intervention during pregnancy. Additionally, this tool may be utilized in data stratification at time of study analyses.

Adverse pregnancy outcomes among women presenting at antenatal clinics in Ouélessébougou, Mali

Background

In sub-Saharan Africa, malaria continues to scourge the population and is the primary cause of morbidity and mortality in young children and pregnant women. As current preventative measures such as intermittent preventive treatment and use of insecticide-treated nets provide incomplete protection, several malaria vaccines are currently under development, including one to specifically prevent pregnancy malaria. Prior to conducting vaccine trials, it is important to obtain background information on poor pregnancy outcomes in the target population to establish a baseline.

Methods

Pregnant women presenting at community health care centers for antenatal care were recruited to the study. Gestational age was determined by ultrasound examination following recruitment. Antenatal care and pregnancy outcome information were collected during a visit 4–8 weeks post-delivery.

Results

One thousand eight hundred fifty women completed the study, and analysis included 1814 women after excluding multiple gestations (n = 26) and missing/incomplete data (n = 10). The percentage (95% CI) of adverse pregnancy outcomes is as follows: miscarriage, 0.28% (0.04–0.52); stillbirth, 1.93% (1.30–2.56); early neonatal death, 1.65% (1.03–2.24); late neonatal death, 0.39%, (0.10–0.68); and preterm delivery (PTD), 4.74% (3.76–5.73). The percentages of early and late neonatal deaths and PTD were significantly higher (p < 0.01) in primigravid compared to multigravid women. In primigravidae, 3.1, 1.1 and 7.1% of pregnancies resulted in early neonatal death, late neonatal death and PTD, respectively, while these outcomes in multigravidae were 1.0, 0.1 and 2.7%, respectively. Major malformations were identified in 4 newborns.

Conclusions

Low gravidity and young age predict perinatal death and PTD. The information collected here can be used as a baseline for adverse pregnancy outcomes in future vaccine trials in pregnant women.

Causality assessment of adverse events following immunization: the problem of multifactorial pathology

The analysis of Adverse Events Following Immunization (AEFI) is important in a balanced epidemiological evaluation of vaccines and in the issues related to national vaccine injury compensation programs. If manufacturing defects or vaccine storage and delivering errors are excluded, the majority of adverse reactions to vaccines occur as excessive or biased inflammatory and immune responses. These unwanted phenomena, occasionally severe, are associated with many different endogenous and exogenous factors, which often interact in complex ways. The confirmation or denial of the causal link between an AEFI and vaccination is determined pursuant to WHO guidelines, which propose a four-step analysis and algorithmic diagramming. The evaluation process from the onset considers all possible "other causes" that can explain the AEFI and thus exclude the role of the vaccine. Subsequently, even if there was biological plausibility and temporal compatibility for a causal association between the vaccine and the AEFI, the guidelines ask to look for any possible evidence that the vaccine could not have caused that event. Such an algorithmic method presents some concerns that are discussed here, in the light of the multifactorial nature of the inflammatory and immune pathologies induced by vaccines, including emerging knowledge of genetic susceptibility to adverse effects. It is proposed that the causality assessment could exclude a consistent association of the adverse event with the vaccine only when the presumed "other cause" is independent of an interaction with the vaccine. Furthermore, the scientific literature should be viewed not as an exclusion criterion but as a comprehensive analysis of all the evidence for or against the role of the vaccine in causing an adverse reaction. These issues are discussed in relation to the laws that, in some countries, regulate the mandatory vaccinations and the compensation for those who have suffered serious adverse effects.

Causality assessment of adverse events following immunization: the problem of multifactorial pathology

The analysis of Adverse Events Following Immunization (AEFI) is important in a balanced epidemiological evaluation of vaccines and in the issues related to vaccine injury compensation programs. The majority of adverse reactions to vaccines occur as excessive or biased inflammatory and immune responses. These unwanted phenomena, occasionally severe, are associated with many different endogenous and exogenous factors, which often interact in complex ways. The confirmation or denial of the causal link between an AEFI and vaccination is determined pursuant to WHO guidelines, which propose a four-step analysis and algorithmic diagramming. The evaluation process from the onset considers all possible "other causes" that might explain the AEFI and thus exclude the role of the vaccine. Subsequently, even if there was biological plausibility and temporal compatibility for a causal association between the vaccine and the AEFI, the guidelines ask to look for any possible evidence that the vaccine could not have caused that event. Such an algorithmic method presents several concerns that are discussed here, in the light of the multifactorial nature of the inflammatory and immune pathologies induced by vaccines, including emerging knowledge of genetic susceptibility to adverse effects. It is proposed that the causality assessment could exclude a consistent association of the adverse event with the vaccine only when the presumed "other cause" is independent of an interaction with the vaccine. Furthermore, the scientific literature should be viewed not as an exclusion criterion but as a comprehensive analysis of all the evidence for or against the role of the vaccine in causing an adverse reaction. Given these inadequacies in the evaluation of multifactorial diseases, the WHO guidelines need to be reevaluated and revised. These issues are discussed in relation to the laws that, in some countries, regulate the mandatory vaccinations and the compensation for those who have suffered serious adverse effects.

Maternal tetanus, diphtheria, and acellular pertussis (Tdap) and influenza immunization: an overview

BACKGROUND

Maternal tetanus, diphtheria, and acellular pertussis (Tdap) and influenza immunization for women during pregnancy (the so-called "maternal immunization") has been introduced in several countries, and recently also in Italy, to protect mother and fetus during pregnancy, infant in his first months of life and mother during postpartum period. However, very low vaccination coverage rates have been reached due to several variables.

METHODS

A literature search was conducted on PubMed and Embase, including any experimental or observational studies, to assesses existing evidence on the effectiveness, efficacy, safety and optimal timing of administration of Tdap and influenza immunization in pregnancy for mothers and their infants. The search was finalized in August 2019.

RESULTS

Reviewing the literature, we identified only a few studies that, among several maternal and infant outcomes, found sporadic significant associations with maternal influenza immunization and even less with Tdap immunization. Moreover, most of the authors of these studies explained these findings as a result of residual confounding effect. The effectiveness of maternal influenza immunization is more complicated to prove than the effectiveness of Tdap immunization because of several reasons. Not all nations recommend and offer vaccines in the same weeks of pregnancy and this one manifests the complexity in defining the best timing for Tdap or influenza immunization.

CONCLUSIONS

The safety of maternal Tdap or influenza immunization is supported by the evidence so far, however, regular surveillance should be maintained, especially with regard to the influenza vaccine that changes in formulation each year. There is a need to optimize the timing of vaccination in pregnancy and to have a national system of detection of maternal immunization in each country.

Pregnant women's knowledge and attitude to maternal vaccination including group B streptococcus and respiratory syncytial virus vaccines

BACKGROUND

Maternal immunisation is an important strategy to reduce neonatal mortality and morbidity. New maternal vaccines such as Respiratory Syncytial Virus (RSV) and Group B streptococcus (GBS) are in development and/or clinical trials. However, little is known about pregnant women's knowledge about these diseases.

METHODS

Women attending antenatal clinics in Melbourne, Australia were invited to complete a questionnaire collecting demographic information, past vaccination history, understanding of risk of GBS and RSV disease in pregnancy and likelihood to accept these theoretical vaccines in the future.

FINDINGS

495 women (48% born outside of Australia, from 48 different countries) completed the questionnaire. A large number of women had never heard of GBS (63%) or RSV (83%). Women over 35 years, born in Australia and women who had more than one child were more likely to have heard of GBS or RSV (p < 0.001). Women who had received influenza or pertussis vaccine in pregnancy were more likely to accept a RSV or GBS vaccine (p < 0.001).

CONCLUSIONS

This study has shown that knowledge of GBS and RSV is poor. However, when provided with information about the two diseases, acceptance of a hypothetical vaccine for both diseases was high. This study highlights the enormous amount of work that needs to be done in educating pregnant women about the seriousness of these two diseases if a future vaccine is ever to be accepted and high coverage achieved among the target population.

Assessing feasibility of resources at health facilities in Uganda to diagnose pregnancy and neonatal outcomes

BACKGROUND

Standardized case definitions for obstetric and neonatal outcomes were developed by the Global Alignment of Immunization Safety Assessment in Pregnancy (GAIA) project. These definitions can facilitate comparable assessment of maternal immunization safety surveillance and research. This study assessed the capabilities of health centers (HC) in Uganda to implement these definitions in a low income country, which has not been explored.

METHODS

Healthcare practitioners at 15 government-accredited health centers and one government-funded district hospital in the Iganga-Mayuge Health and Demographic Surveillance Site (IMHDSS) in Uganda were interviewed about the facility's clinical diagnostic and laboratory capabilities. Five obstetric and five neonatal case definitions were evaluated. Definitions with the highest diagnostic certainty were designated as level 1, while definitions that decreased in certainty were designated as level 2 or 4. HCs were evaluated on diagnostic and laboratory capabilities to apply the GAIA definitions.

RESULTS

Higher-level facilities in the IMHDSS demonstrated the ability to diagnose more specific levels of the GAIA obstetric and neonatal outcomes than lower-level facilities. Furthermore, for the neonatal outcome assessment, there was an increased ability to diagnose outcomes moving from GAIA level 1 to level 3.

CONCLUSIONS

The ability of health centers to implement globally standardized definitions is promising for implementation of standardized data collection methods for global vaccine safety surveillance and research.

Defining the interval for monitoring potential adverse events following immunization (AEFIs) after receipt of live viral vectored vaccines

Live viral vectors that express heterologous antigens of the target pathogen are being investigated in the development of novel vaccines against serious infectious agents like HIV and Ebola. As some live recombinant vectored vaccines may be replication-competent, a key challenge is defining the length of time for monitoring potential adverse events following immunization (AEFI) in clinical trials and epidemiologic studies. This time period must be chosen with care and based on considerations of pre-clinical and clinical trials data, biological plausibility and practical feasibility. The available options include: (1) adapting from the current relevant regulatory guidelines; (2) convening a panel of experts to review the evidence from a systematic literature search to narrow down a list of likely potential or known AEFI and establish the optimal risk window(s); and (3) conducting "near real-time" prospective monitoring for unknown clustering's of AEFI in validated large linked vaccine safety databases using Rapid Cycle Analysis for pre-specified adverse events of special interest (AESI) and Treescan to identify previously unsuspected outcomes. The risk window established by any of these options could be used along with (4) establishing a registry of clinically validated pre-specified AESI to include in case-control studies. Depending on the infrastructure, human resources and databases available in different countries, the appropriate option or combination of options can be determined by regulatory agencies and investigators.

Current Challenges and Achievements in Maternal Immunization Research

Maternal immunization has the potential to significantly improve maternal and child health worldwide by reducing maternal and infant morbidity and mortality associated with disease caused by pathogens that are particularly relevant in the perinatal period and in early life, and for which no alternative effective preventive strategies exist. Research on all aspects related to vaccines for administration during pregnancy is ongoing with support of multiple stakeholders and global participation. Substantial progress has been made, and the availability of new vaccines licensed exclusively for use in pregnant women to protect their infants has become an achievable goal. This review provides an update of the current challenges and achievements in maternal immunization research, focusing on recent milestones that advance the field and the prospects to make maternal immunization a feasible and accessible strategy to improve global health.

Who's the Target: Mother or Baby?

Maternal immunization for prevention of morbidity and mortality of pregnant women and their neonates due to infectious diseases is ongoing worldwide. The complexity of vaccine research and development in this population is challenging. Not only do vaccines for pregnant women require evidence of immunogenicity, potency, stability, and limited reactogenicity, they must also provide efficacy in decreasing morbidity for the pregnant woman, her fetus, and the neonate, demonstrate safety or lack of evidence of harm, and offer benefit or potential benefit of vaccination during pregnancy. Since the 19th century, evidence of protective effects of vaccination during pregnancy has been documented. Pandemic influenza and pertussis outbreaks in recent years have affected a paradigm shift in vaccine research and development as well as current policy regarding immunization in pregnancy. Studies of the immune system in pregnant women and neonates have shown that immune changes associated with pregnancy in women do not interfere with maternal vaccine responses, multiple factors are important in transplacental transfer of antibodies, and maternal antibodies are beneficial to neonates. In recent years, guidelines have been developed by expert panels to help design studies for maternal vaccinations and for harmonization of data collection, analysis, and adverse event reporting. Further research into maternal and neonatal immunology, transplacental antibody transfer, and epidemiology of diseases is needed, especially as new vaccines to respiratory syncytial virus, cytomegalovirus, and Group B streptococcus are developed. Maternal vaccinations have the potential to change the epidemiology of infectious diseases in reproductive health and pediatrics and may lead to new clinical applications to improve global maternal and neonatal health.

Factors influencing access of pregnant women and their infants to their local healthcare system: a prospective, multi-centre, observational study

Background

The successful implementation of maternal vaccination relies on results of clinical trials, considering the prenatal and postnatal attendance at selected healthcare institutions. This study evaluated factors influencing maternal/infant access to healthcare facilities to identify potential barriers to participation in future clinical trials on maternal vaccination.

Methods

In this prospective, multi-centre, observational study, pregnant women (N = 3243) were enrolled at ten sites across Panama, the Dominican Republic, South Africa, and Mozambique between 2012 and 2014. They completed questionnaires at enrolment, delivery, and infant follow-up (90 days post-partum) visits, including questions on transportation, phone accessibility, alternative childcare, gestational age at enrolment, delivery location, and health status of their infant. Logistic regression was used to identify factors significantly associated with return to study site for delivery or infant follow-up visits.

Results

Among 3229 enrolled women with delivery information, 63.6% (range across sites: 25.3–91.5%) returned to study site for delivery. Older women and those at later gestational age at enrolment were more likely to deliver at the study site. While heterogeneities were observed at site level, shorter travel time at delivery and increased transportation costs at enrolment were associated with increased likelihood of women returning to study site for delivery. Among 3145 women with live-born infants, 3077 (95.3%) provided 90-day follow-up information; of these, 68.9% (range across sites: 25.6–98.9%) returned to study site for follow-up visits. Women with other children and with lower transportation costs at delivery were more likely to return to study site for follow-up visits. Among 666 infants reported sick, 94.3% were taken to a healthcare facility, with only 41.9% (range across sites: 4.9–77.3%) to the study site.

Conclusion

Although high retention was observed from enrolment through 90 days after delivery, post-partum surveillance should be broadened beyond the study sites and additional follow-up visits should be planned within the neonatal period. The factors influencing maternal/infant access to healthcare facilities and the issues identified in this study should be taken into consideration in planning future clinical studies on maternal immunisation in low- and middle-income countries.

Trial registration

The study was registered at ClinicalTrial.gov (NCT01734434) on November 22, 2012.

Electronic supplementary material

The online version of this article (10.1186/s12884-017-1655-3) contains supplementary material, which is available to authorized users.

Influenza immunization of pregnant women in resource-constrained countries: an update for funding and implementation decisions

PURPOSE OF REVIEW

In 2018, Gavi, the Vaccine Alliance, is expected to review the strategy of maternal influenza immunization for potential investment in low-income countries.

RECENT FINDINGS

Clinical trial data confirm the efficacy of maternal influenza immunization to prevent influenza disease in both mothers and their infants during the first months of life. Trial and observational data indicate no significant adverse events in mothers or newborns. High-quality disease burden data, particularly for seasonal influenza in low-income and middle-income countries, are limited. Thus, the anticipated impact of maternal influenza immunization programs on severe illness is unclear. However, assessments of the public health value of investment in maternal influenza immunization should extend beyond calculations of disease prevention and include broader effects such as improving health systems for antenatal care delivery, preventing inappropriate antibacterial prescribing, building a platform for other vaccines to be used during pregnancy, and strengthening systems to regulate, procure, and distribute influenza vaccines in response to a future pandemic.

SUMMARY

A global investment in a maternal influenza immunization strategy would prevent influenza disease in pregnant women and their infants. It would also provide additional public health value by strengthening antenatal care systems and improving country pandemic preparedness.

Efficacy and safety of pertussis vaccination for pregnant women - a systematic review of randomised controlled trials and observational studies

BACKGROUND

Worldwide, pertussis remains a major health problem among children. During the recent outbreaks of pertussis, maternal antenatal immunisation was introduced in several industrial countries. This systematic review aimed to synthesize evidence for the efficacy and safety of the pertussis vaccination that was given to pregnant women to protect infants from pertussis infection.

METHODS

We searched literature in the Cochrane Central Register of Controlled Trials, Medline, Embase, and OpenGrey between inception of the various databases and 16 May 2016. The search terms included 'pertussis', 'whooping cough', 'pertussis vaccine,' 'tetanus, diphtheria and pertussis vaccines' and 'pregnancy' and 'perinatal'.

RESULTS

We included 15 articles in this review, which represented 12 study populations, involving a total of 203,835 mother-infant pairs from the US, the UK, Belgium, Israel, and Vietnam. Of the included studies, there were two randomised controlled trials (RCTs) and the rest were observational studies. Existing evidence suggests that vaccinations administered during 19-37 weeks of gestation are associated with significantly increased antibody levels in the blood of both mothers and their newborns at birth compared to placebo or no vaccination. However, there is a lack of robust evidence to suggest whether these increased antibodies can also reduce the incidence of pertussis (one RCT, n = 48, no incidence in either group) and pertussis-related severe complications (one observational study) or mortality (no study) in infants. Meanwhile, there is no evidence of increased risk of serious complications such as stillbirth (e.g. one RCT, n = 103, RR = 0, meaning no case in the vaccine group), or preterm birth (two RCTs, n = 151, RR = 0.86, 95%CI: 0.14-5.21) related to administration of the vaccine during pregnancy.

CONCLUSION

Given that pertussis infection is increasing in many countries and that newborn babies are at greatest risk of developing severe complications from pertussis, maternal vaccination in the later stages of pregnancy should continue to be supported while further research should fill knowledge gaps and strengthen evidence of its efficacy and safety.

Immunization During Pregnancy: Impact on the Infant

Maternal immunization has undergone a paradigm shift in recent years, as women and healthcare providers accept and recognize the benefits of this strategy not only for the pregnant woman but also for the developing fetus and young infant. This article reviews the evidence for active immunization during pregnancy, with an emphasis on perinatal and infant outcomes. Current recommendations for immunization during pregnancy are presented, with particular focus on the routinely recommended vaccines during pregnancy: influenza and Tdap (tetanus, diphtheria, and pertussis). We discuss future research directions, maternal vaccines in development, and considerations for optimizing and advancing this underutilized strategy.

Immunization in pregnancy clinical research in low- and middle-income countries - Study design, regulatory and safety considerations

Immunization of pregnant women is a promising public health strategy to reduce morbidity and mortality among both the mothers and their infants. Establishing safety and efficacy of vaccines generally uses a hybrid design between a conventional interventional study and an observational study that requires enrolling thousands of study participants to detect an unknown number of uncommon events. Historically, enrollment of pregnant women in clinical research studies encountered many barriers based on risk aversion, lack of knowledge, and regulatory ambiguity. Conducting research enrolling pregnant women in low- and middle-income countries can have additional factors to address such as limited availability of baseline epidemiologic data on disease burden and maternal and neonatal outcomes during and after pregnancy; challenges in recruiting and retaining pregnant women in research studies, variability in applying and interpreting assessment methods, and variability in locally acceptable and available infrastructure. Some measures to address these challenges include adjustment of study design, tailoring recruitment, consent process, retention strategies, operational and logistical processes, and the use of definitions and data collection methods that will align with efforts globally.

Association of influenza vaccination during pregnancy with birth outcomes in Nicaragua

Background: Studies have shown that influenza vaccination during pregnancy reduces the risk of influenza disease in pregnant women and their offspring. Some have proposed that maternal vaccination may also have beneficial effects on birth outcomes. In 2014, we conducted an observational study to test this hypothesis using data from two large hospitals in Managua, Nicaragua.

Methods: We conducted a retrospective cohort study to evaluate associations between influenza vaccination and birth outcomes. We carried out interviews and reviewed medical records post-partum to collect data on demographics, influenza vaccination during pregnancy, birth outcomes and other risk factors associated with adverse neonatal outcomes. We used influenza surveillance data to adjust for timing of influenza circulation. We assessed self-reports of influenza vaccination status by further reviewing medical records of those who self-reported but did not have readily available evidence of vaccination status. We performed multiple logistic regression (MLR) and propensity score matching (PSM).

Results: A total of 3268 women were included in the final analysis. Of these, 55% had received influenza vaccination in 2014. Overall, we did not observe statistically significant associations between influenza vaccination and birth outcomes after adjusting for risk factors, with either MLR or PSM. With PSM, after adjusting for risk factors, we observed protective associations between influenza vaccination in the second and third trimester and preterm birth (aOR: 0.87; 95% confidence interval (CI): 0.75–0.99 and aOR: 0.66; 95% CI: 0.45–0.96, respectively) and between influenza vaccination in the second trimester and low birth weight (aOR: 0.80; 95% CI: 0.64–0.97).

Conclusions: We found evidence to support an association between influenza vaccination and birth outcomes by trimester of receipt with data from an urban population in Nicaragua. The study had significant selection and recall biases. Prospective studies are needed to minimize these biases.

Pertussis vaccination in pregnancy: State of the art

Pertussis vaccination in pregnancy has been introduced by several national advisory bodies, mostly in industrialized countries, as a means to protect young infants from disease by high titers of maternal antibodies. Most recommendations derive from epidemiological needs, but many knowledge gaps remained after implementation. This report aims to overview the solved and unsolved aspects of prenatal vaccination with a pertussis containing vaccine.

Global alignment of immunization safety assessment in pregnancy - The GAIA project

Immunization in pregnancy provides a promising contribution to globally reducing neonatal and under-five childhood mortality and morbidity. Thorough assessment of benefits and risks for the primarily healthy pregnant women and their unborn babies is required. The GAIA project was formed in response to the call of the World Health Organization for a globally concerted approach to actively monitor the safety of vaccines and immunization in pregnancy programs. GAIA aims to improve the quality of outcome data from clinical vaccine trials in pregnant women with a specific focus on the needs and requirements for safety monitoring in LMIC. In the first year of the project, a large and functional network of experts was created. The first outputs include a guidance document for clinical trials of immunization in pregnancy, a basic data collection guide, ten case definitions of key obstetric and neonatal health outcomes, an ontology of key terms and a map of pertinent disease codes. The GAIA Network is designed as an open and growing forum for professionals sharing the GAIA vision and aim. Based on the initial achievements, tools and services are developed to support investigators and strengthen immunization in pregnancy programs with specific focus on LMIC.