Safety evaluation of adverse events following vaccination with Havrix, Engerix-B or Twinrix during pregnancy

Hepatitis B Vaccine: Four Decades on

Hepatitis B virus is a substantial contributor to cirrhosis and hepatocellular carcinoma (HCC) globally. Vaccination is the most effective method for prevention of hepatitis B and its associated morbidity and mortality, and the only method to prevent infection with hepatitis D virus. The hepatitis B vaccine has been used worldwide for more than four decades; it is available in a single- or triple-antigen form and in combination with vaccines against other infections. Introduction of the vaccine and administration at birth led to sustained decline in mother-to-child transmission, chronic hepatitis B, and HCC, however, global birth dose coverage remains suboptimal. In this review we will discuss different hepatitis B vaccine formulations and schedules, vaccination guidelines, durability of the response, and vaccine escape mutants, as well as the clinical and economic benefits of vaccination.

A Systematic Review of Population-Based Studies Assessing Knowledge, Attitudes, Acceptance, and Hesitancy of Pregnant and Breastfeeding Women towards the COVID-19 Vaccine

The anti-SARS-CoV-2 vaccination is recommended for pregnant women due to the high risk of complications. However, pregnancy has been associated with vaccine hesitancy. Our review aims at summarizing the existing literature about anti-SARS-CoV-2 vaccine hesitancy in pregnant and lactating women. The research was conducted on PubMed/MEDLINE, ExcerptaMedica Database (EMBASE), and Scopus, according to PRISMA guidelines. Articles regarding the COVID-19 vaccine's acceptance and/or refusal by pregnant and lactating women were selected. Only observational, population-based studies were included. The Joanna Briggs Institute quality assessment tools were employed. A total of 496 articles were retrieved, and after the selection process, 21 papers were included in the current analysis. All the included studies were cross-sectional, mostly from Europe and North America. The sample sizes ranged between 72 and 25,111 subjects. All of them included pregnant subjects, except one that focused on breastfeeding women only. Vaccine hesitancy rates ranged from 26% to 57% among different studies. Fear of adverse events and lack of knowledge were shown to be the main drivers of hesitancy. Approximately half of the studies (11/21) were classified as low quality, the remaining (9/21) were classified as moderate, and only one study was classified as high quality. Primigravidae were also shown to be more likely to accept anti-SARS-CoV-2 vaccination. Our findings confirm significant anti-SARS-CoV-2 vaccine hesitancy among pregnant women. Information gaps should be addressed to contain concerns related to adverse events.

Safety and immunogenicity of HepB-CpG in women with documented pregnancies post-vaccination: A retrospective chart review

BACKGROUND

There are currently no published data on the use of HepB-CpG (HEPLISAV-B®) during pregnancy or in women with documented pregnancies in the post-vaccination period. We aimed to evaluate data from the clinical development program of HepB-CpG in women who became pregnant during study participation and follow up.

METHODS

We identified all study participants in the HepB-CpG pivotal pre-licensure clinical trials that had documented pregnancies during study follow up. We measured immunogenicity among study participants in the HepB-CpG (Heplisav-B®) arm compared to the HepB-alum (Engerix-B®) arm of the studies by comparing seroprotection rates (SPRs; anti-HBs ≥ 10 mIU/mL) and geometric mean concentrations (GMCs) of anti-HBs, obtained with FDA approved anti-HBsAg antibody assays at prespecified time points up to 28 weeks of follow up. Pregnancy outcomes were ascertained by chart review of extracted medical records of study participants.

RESULTS

We identified 40 documented pregnancies in the HepB-CpG arm and 19 documented pregnancies in the HepB-alum arm. Among subjects with documentation of seroprotection rates, 97.2% (95% CI 85.5-99.9) were seroprotected in the HepB-CpG arm and 66.7% (95% CI 41.0-86.7) were seroprotected in the HepB-alum arm. In the HepB-CpG arm, thirty-six study participants from the pivotal trials had reported pregnancy outcomes, the majority, 21/36 (58%) had a healthy term delivery, with 3/36 (8%) with spontaneous abortions, 1/36 (3%) congenital anomaly, and 2/36 (6%) had preterm birth. In the HepB-alum arm, 10/17 (59%) had healthy term deliveries, with 2/17 (12%) had spontaneous abortions and 1/17 (6%) had congenital anomaly.

CONCLUSIONS

These limited data suggest that HepB-CpG is immunogenic in women who become pregnant after vaccination, and pregnancy outcomes appear to be similar to women who received HepB-alum prior to pregnancy. These results need to be further verified with larger prospective studies with HBV vaccine administration during pregnancy.

Vaccines

The safety of COVID-19 vaccines, as was the case last year, remains a large part of the focus in this volume. COVID-19 placed a large magnifying glass on both vaccines, specifically vaccine safety. This was most readily apparent as the number of records in VAERS ballooned to about 10 times the size from 2020 to 2021 (Vaccine Adverse Event Reporting System (VAERS), 2022) [S]. While we have added and/or improved VAERS during COVID-19, including adding or improving other vaccine safety surveillance tools like v-safe and vaccine safety datalink (Blumenthal, Phadke, et al., 2021) [MC], there is still room for improvement in these pharmacovigilance tools (Rizk et al., 2021) [r]. A major global initiative in this realm is the Global Vaccines Safety Blueprint 2.0 (GVSB2.0) (Organization, 2021, pp. 2021–2023) [S]. We wholeheartedly endorse these initiatives, which could significantly improve vaccine safety.

As noted in past SEDA issues, clinicians should be mindful of the risks of AEs and SAEs associated with each individual vaccine.

Safety of components and platforms of COVID-19 vaccines considered for use in pregnancy: A rapid review

BACKGROUND

Rapid assessment of COVID-19 vaccine safety during pregnancy is urgently needed.

METHODS

We conducted a rapid systematic review, to evaluate the safety of COVID-19 vaccines selected by the COVID-19 Vaccines Global Access-Maternal Immunization Working Group in August 2020, including their components and their technological platforms used in other vaccines for pregnant persons. We searched literature databases, COVID-19 vaccine pregnancy registries, and explored reference lists from the inception date to February 2021 without language restriction. Pairs of reviewers independently selected studies through COVIDENCE, and performed the data extraction and the risk of bias assessment. Discrepancies were resolved by consensus. Registered on PROSPERO (CRD42021234185).

RESULTS

We retrieved 6757 records and 12 COVID-19 pregnancy registries from the search strategy; 38 clinical and non-clinical studies (involving 2,398,855 pregnant persons and 56 pregnant animals) were included. Most studies (89%) were conducted in high-income countries and were cohort studies (57%). Most studies (76%) compared vaccine exposures with no exposure during the three trimesters of pregnancy. The most frequent exposure was to AS03 adjuvant, in the context of A/H1N1 pandemic influenza vaccines, (n = 24) and aluminum-based adjuvants (n = 11). Only one study reported exposure to messenger RNA in lipid nanoparticles COVID-19 vaccines. Except for one preliminary report about A/H1N1 influenza vaccination (adjuvant AS03), corrected by the authors in a more thorough analysis, all studies concluded that there were no safety concerns.

CONCLUSION

This rapid review found no evidence of pregnancy-associated safety concerns of COVID-19 vaccines or of their components or platforms when used in other vaccines. However, the need for further data on several vaccine platforms and components is warranted, given their novelty. Our findings support current WHO guidelines recommending that pregnant persons may consider receiving COVID-19 vaccines, particularly if they are at high risk of exposure or have comorbidities that enhance the risk of severe disease.

Safety of COVID-19 vaccines, their components or their platforms for pregnant women: A rapid review

BACKGROUND

Pregnant women with COVID-19 are at an increased risk of severe COVID-19 illness as well as adverse pregnancy and birth outcomes. Many countries are vaccinating or considering vaccinating pregnant women with limited available data about the safety of this strategy. Early identification of safety concerns of COVID-19 vaccines, including their components, or their technological platforms is therefore urgently needed.

METHODS

We conducted a rapid systematic review, as the first phase of an ongoing full systematic review, to evaluate the safety of COVID-19 vaccines in pregnant women, including their components, and their technological platforms (whole virus, protein, viral vector or nucleic acid) used in other vaccines, following the Cochrane methods and the PRISMA statement for reporting (PROSPERO-CRD42021234185).We searched literature databases, COVID-19 and pregnancy registries from inception February 2021 without time or language restriction and explored the reference lists of relevant systematic reviews retrieved. We selected studies of any methodological design that included at least 50 pregnant women or pregnant animals exposed to the vaccines that were selected for review by the COVAX MIWG in August 2020 or their components or platforms included in the COVID-19 vaccines, and evaluated adverse events during pregnancy and the neonatal period.Pairs of reviewers independently selected studies through the COVIDENCE web software and performed the data extraction through a previously piloted online extraction form. Discrepancies were resolved by consensus.

RESULTS

We identified 6768 records, 256 potentially eligible studies were assessed by full-text, and 37 clinical and non-clinical studies (38 reports, involving 2,397,715 pregnant women and 56 pregnant animals) and 12 pregnancy registries were included.Most studies (89%) were conducted in high-income countries. The most frequent study design was cohort studies (n=21), followed by surveillance studies, randomized controlled trials, and registry analyses. Most studies (76%) allowed comparisons between vaccinated and unvaccinated pregnant women (n=25) or animals (n=3) and reported exposures during the three trimesters of pregnancy.The most frequent exposure was to AS03 adjuvant in the context of A/H1N1 pandemic influenza vaccines (n=24), followed by aluminum-based adjuvants (n=11). Aluminum phosphate was used in Respiratory Syncytial Virus Fusion candidate vaccines (n=3) and Tdap vaccines (n=3). Different aluminum-based adjuvants were used in hepatitis vaccines. The replication-deficient simian adenovirus ChAdOx1 was used for a Rift Valley fever vaccine. Only one study reported exposure to messenger RNA (mRNA) COVID-19 vaccines that also used lipid nanoparticles. Except for one preliminary report about A/H1N1 influenza vaccination (adjuvant AS03) - corrected by the authors in a more thorough analysis, all studies concluded that there were no safety concerns.

CONCLUSION

This rapid review found no evidence of pregnancy-associated safety concerns of COVID-19 vaccines that were selected for review by the COVAX MIWG or of their components or platforms when used in other vaccines. However, the need for further data on several vaccine platforms and components is warranted given their novelty. Our findings support current WHO guidelines recommending that pregnant women may consider receiving COVID-19 vaccines, particularly if they are at high risk of exposure or have comorbidities that enhance the risk of severe disease.

Vaccines

In this volume of the Side Effects of Drugs Annual, although other vaccines will be covered, the safety of COVID vaccines is the focus as COVID-19 has led to heightened attention on vaccine safety in general. As such, this chapter will be more relevant than ever before. As noted in past SEDA issues, clinicians should be mindful of the risks of AEs and SAEs associated with each vaccine.