Elective termination of pregnancy after vaccination reported to the Vaccine Adverse Event Reporting System (VAERS): 1990-2006

Miscarriage after SARS-CoV-2 vaccination: A population-based cohort study

OBJECTIVE

To evaluate the risk of miscarriage following SARS-CoV-2 vaccination, while accounting for the competing risk of induced abortion.

DESIGN

Population-based cohort study.

SETTING

Ontario, Canada.

PARTICIPANTS

Women aged 15-50 years with a confirmed pregnancy at ≤19 completed weeks' gestation.

METHODS

Exposure to first SARS-CoV-2 vaccination, handled in a time-varying manner, was defined as (i) unvaccinated, (ii) remotely vaccinated >28 days before the estimated conception date or (iii) recently vaccinated ≤28 days before conception and up to 120 days after conception.

MAIN OUTCOME MEASURES

The outcome was miscarriage, occurring between the estimated date of conception and up to 19 completed weeks of pregnancy. Fine-Grey hazard models, accounting for the competing risk of induced abortion, generated hazard ratios (aHR), adjusted for socio-demographic factors, comorbidities, and biweekly periods.

RESULTS

Included were 246 259 pregnant women, of whom 34% received a first SARS-CoV-2 vaccination. Miscarriage occurred at a rate of 3.6 per 10 000 person-days among remotely vaccinated women and 3.2 per 10 000 person-days among those recently vaccinated, in contrast to a rate of 1.9 per 10 000 person-days among unvaccinated women, with corresponding aHR of 0.98 (95% confidence interval [CI] 0.91-1.07) and 1.00 (95% CI 0.93-1.08).

CONCLUSIONS

SARS-CoV-2 vaccination was not associated with miscarriage while accounting for the competing risk of induced abortion. This study reiterates the importance of including pregnant women in new vaccine clinical trials and registries, and the rapid dissemination of vaccine safety data.

Protective vaccinations during pregnancy - adult Poles knowledge in this area

BACKGROUND

The vaccine is a preparation of biological origin containing antigens that stimulate the body's immune system to produce acquired immunity. Vaccines can contain killed or "live" (attenuated) microorganisms as well as fragments of these (antigens). Although many vaccines are used routinely in pregnancy to provide a seroprotective immune response for mother, fetus and neonate there is much controversy over their use during this unique time. The aim of the study was to find out about the knowledge of adult Poles on the use of preventive vaccinations during pregnancy.

METHODS

The study involved 700 people (100%) aged 18 to 80 years ([Formula: see text] = 32.16 ± 16.46). Most of the respondents were women (511; 73%). The study consisted of 9 questions about preventive vaccinations of pregnant women and 5 questions about members of the studied group. The aforementioned questions formed the basis of the preparation of the presented article.

RESULTS

A significant part of respondents (322; 46%) did not have knowledge on the topic of safeness of using preventive vaccinations during pregnancy, 196 (28%) respondents believed that such procedure is not safe. Most of the respondents (371; 53%) did not know about the possibility of using "live" vaccines during pregnancy. 14 (2%) of respondents believed that pregnancy should be terminated in case of administration of a "live" vaccine to a pregnant woman. According to 294 (42%) respondents, vaccinations with "live" vaccines should be completed at least 3 months before the planned pregnancy. The subjects were not aware of the issue of post-exposure vaccination against tetanus and rabies among pregnant women. The respondents' responses were divided on the issue of the safest trimester of pregnancy for vaccine administration. Almost 1/3 of the respondents (203; 29%) indicated the third trimester as the safest for their performance.

CONCLUSION

The knowledge of the surveyed group, the majority of whom were women, about the use of vaccinations before and during pregnancy was unsatisfactory. There is a need to educate the public about the benefits and risks of performing or avoiding preventive vaccinations during pregnancy.

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.

Vaccinations during pregnancy: a call to sting into action

Safety and efficacy of vaccinations during pregnancy have been a matter of debate. In the aftermath of the 2009 H1N1 influenza pandemic, a growing body of research has emerged, which points toward the importance of adhering to influenza vaccination recommendations for pregnant women. The same applies for vaccination against pertussis. Some vaccines (e.g., live attenuated) are still contraindicated during pregnancy. However, data indicate that these vaccines do not result in fetal impairment when administered accidentally during pregnancy. In the following, we provide a review on vaccination-related safety and efficacy aspects in pregnant women, shedding some light on potential barriers that stymie vaccination uptake among pregnant women and introducing strategies to overcome these barriers.

Sex and Gender Differences in the Outcomes of Vaccination over the Life Course

Both sex (i.e., biological differences) and gender (i.e., social or cultural influences) impact vaccine acceptance, responses, and outcomes. Clinical data illustrate that among children, young adults, and aged individuals, males and females differ in vaccine-induced immune responses, adverse events, and protection. Although males are more likely to receive vaccines, following vaccination, females typically develop higher antibody responses and report more adverse effects of vaccination than do males. Human, nonhuman animal, and in vitro studies reveal numerous immunological, genetic, hormonal, and environmental factors that differ between males and females and contribute to sex- and gender-specific vaccine responses and outcomes. Herein, we address the impact of sex and gender variables that should be considered in preclinical and clinical studies of vaccines.

Statistical and Ontological Analysis of Adverse Events Associated with Monovalent and Combination Vaccines against Hepatitis A and B Diseases

Vaccinations often induce various adverse events (AEs), and sometimes serious AEs (SAEs). While many vaccines are used in combination, the effects of vaccine-vaccine interactions (VVIs) on vaccine AEs are rarely studied. In this study, AE profiles induced by hepatitis A vaccine (Havrix), hepatitis B vaccine (Engerix-B), and hepatitis A and B combination vaccine (Twinrix) were studied using the VAERS data. From May 2001 to January 2015, VAERS recorded 941, 3,885, and 1,624 AE case reports where patients aged at least 18 years old were vaccinated with only Havrix, Engerix-B, and Twinrix, respectively. Using these data, our statistical analysis identified 46, 69, and 82 AEs significantly associated with Havrix, Engerix-B, and Twinrix, respectively. Based on the Ontology of Adverse Events (OAE) hierarchical classification, these AEs were enriched in the AEs related to behavioral and neurological conditions, immune system, and investigation results. Twenty-nine AEs were classified as SAEs and mainly related to immune conditions. Using a logistic regression model accompanied with MCMC sampling, 13 AEs (e.g., hepatosplenomegaly) were identified to result from VVI synergistic effects. Classifications of these 13 AEs using OAE and MedDRA hierarchies confirmed the advantages of the OAE-based method over MedDRA in AE term hierarchical analysis.

Monitoring for teratogenic signals: pregnancy registries and surveillance methods

Pregnant women should have access to medications that have been adequately studied for use to facilitate evidence-based risk-benefit discussions with their health care providers. Pregnant women experience acute medical emergencies, have existing conditions that require continued medical treatment or may develop pregnancy-induced conditions, making drug use during pregnancy unavoidable. Drug labeling is the primary source of information about a drug's use. The safety and efficacy data found in the label is derived from well-controlled clinical trials conducted prior to a drug's approval. However, pregnant women are rarely enrolled in clinical trials unless a product is specifically indicated for a pregnancy-related condition. Consequently, information regarding a product's use during pregnancy is usually collected postapproval. Current data collection tools include pregnancy exposure registries, retrospective cohort studies, pregnancy surveillance programs, case-control studies, spontaneous reports of adverse events and case reports. Each tool has strengths and limitations in its ability to detect teratogenic signals. Combinations of different sources of data are necessary to acquire the most complete picture of potential teratogenic risk, as no single method can capture all desired data to help pregnant patients and women of child bearing potential make appropriate risk benefits decisions along with their health care providers.

Vaccination in Pregnancy

Vaccination is one of the most effective strategies employed to prevent morbidity and mortality from infectious diseases. Pregnancy is considered to be a time when women have consistent contact with their healthcare providers and it presents an opportunity for providers to review their immunization status and to advocate for appropriate vaccination antepartum and in the immediate postpartum period. All forms of immunization, with the exception of live viral or live bacterial vaccines are generally considered to be safe for administration during pregnancy. It is important that healthcare providers counsel pregnant women about the benefits of receiving the vaccines that are recommended during pregnancy as well as the potential risks to the developing fetus. It is imperative that obstetricians and primary care providers are aware of and implement the vaccination guidelines for women, both during pregnancy and in the postpartum period.

The Xs and Y of immune responses to viral vaccines

The biological differences associated with the sex of an individual are a major source of variation, affecting immune responses to vaccination. Compelling clinical data illustrate that men and women differ in their innate, humoral, and cell-mediated responses to viral vaccines. Sex affects the frequency and severity of adverse effects of vaccination, including fever, pain, and inflammation. Pregnancy can also substantially alter immune responses to vaccines. Data from clinical trials and animal models of vaccine efficacy lay the groundwork for future studies aimed at identifying the biological mechanisms that underlie sex-specific responses to vaccines, including genetic and hormonal factors. An understanding and appreciation of the effect of sex and pregnancy on immune responses might change the strategies used by public health officials to start efficient vaccination programmes (optimising the timing and dose of the vaccine so that the maximum number of people are immunised), ensure sufficient levels of immune responses, minimise adverse effects, and allow for more efficient protection of populations that are high priority (eg, pregnant women and individuals with comorbid conditions).

Unintended vaccination of pregnant adolescents: estimating the scope of the problem and the impact of different pregnancy testing strategies

Among a hypothetical cohort of 11-18-year-old females, we used a probabilistic decision tree model to estimate the number of pregnant adolescent females potentially receiving contraindicated vaccines during well child exams, and to determine the impact of two different pregnancy screening strategies on pregnancy detection rates, vaccine administration and pregnancy detection-associated costs. We found that under current practice conditions, the majority (95-99%) of adolescent pregnancies are likely missed during well child exams, allowing the opportunity to administer contraindicated vaccines. A strategy to test everyone detected the highest proportion of pregnancies, but at a substantial financial cost (USD 12,270,037-USD 19,430,607). Testing was more efficient for older adolescents, but both testing strategies were associated with a significant number of false positive test results (41-98%), regardless of age. These results suggest that systematic pregnancy screening strategies would be effective for preventing pregnant adolescents from receiving contraindicated vaccines, but may not be worth the potentially high financial and psychological costs.