Vaccination of Pregnant Women Against COVID-19

Trends in COVID-19 diagnoses and outcomes in infants hospitalized in the neonatal intensive care unit

OBJECTIVE

Characterize the prevalence of coronavirus disease 2019 (COVID-19) diagnosis among mothers with infants hospitalized in 294 neonatal intensive care units (NICUs), and demographics and outcomes of infants with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure in utero.

STUDY DESIGN

Cohort study of infants discharged from NICUs 01/2020-09/2021. We defined groups based on infant diagnosis, infant testing, and maternal SARS-CoV-2 infection status. We compared demographics, clinical characteristics, and outcomes.

RESULTS

Of 150,924 infants, 94% had no COVID-related diagnosis or test; 247 (0.2%) infants tested positive for COVID-19 and were more likely to require mechanical ventilation. Infants with unknown maternal status and negative testing were more commonly premature, outborn, and had longer hospitalizations.

CONCLUSION

In this large cohort of hospitalized infants, most had no known exposure to COVID-19. Adverse outcomes and mortality were rare. Further studies are needed to evaluate the long-term effects of COVID-19 in this population.

Policy and Guideline Review of Vaccine Safety for COVID-19 in Pregnant Women in Southern Africa, with a Particular Focus on South Africa

Pregnant and lactating mothers have historically been excluded from clinical trials. To understand the shift from excluding to including this population in COVID-19 vaccine trials, we conducted a review of guidance issued by countries in southern Africa over the last three years. We conducted a review of documents and official statements recorded on Ministries of Health websites, and social media platforms, the World Health Organisation website, the COVID-19 Maternal Immunisation tracker and the African Union official webpage. Search terms included COVID-19 vaccination policies, guidelines for pregnant and lactating women, COVID-19 vaccination trials and pregnant women. We retrieved and reviewed policies, guidelines, and official statements from 12 countries. We found inconsistencies and incomplete guidance in respect to the inclusion of pregnant and lactating mothers in COVID-19 vaccine trials from the selected countries. Of the twelve countries reviewed, Namibia and South Africa had clear guidance on vaccination plans and implementation for pregnant women, and their inclusion in COVID-19 vaccine trials. Explicit and clear guidelines are critical in communicating changes in policy towards those deemed vulnerable for them to participate in vaccine trials. This review provides lessons for future pandemics on managing changes in guidance towards those groups historically excluded from vaccine and clinical trials.

Comparison of Maternal and Neonatal Antibody Levels After COVID-19 Vaccination vs SARS-CoV-2 Infection

IMPORTANCE

Pregnant persons are at an increased risk of severe COVID-19 from SARS-CoV-2 infection, and COVID-19 vaccination is currently recommended during pregnancy.

OBJECTIVE

To ascertain the association of vaccine type, time from vaccination, gestational age at delivery, and pregnancy complications with placental transfer of antibodies to SARS-CoV-2.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted in Pennsylvania Hospital in Philadelphia, Pennsylvania, and included births at the study site between August 9, 2020, and April 25, 2021. Maternal and cord blood serum samples were available for antibody level measurements for maternal-neonatal dyads.

EXPOSURES

SARS-CoV-2 infection vs COVID-19 vaccination.

MAIN OUTCOMES AND MEASURES

IgG antibodies to the receptor-binding domain of the SARS-CoV-2 spike protein were measured by quantitative enzyme-linked immunosorbent assay. Antibody concentrations and transplacental transfer ratios were measured after SARS-CoV-2 infection or receipt of COVID-19 vaccines.

RESULTS

A total of 585 maternal-newborn dyads (median [IQR] maternal age, 31 [26-35] years; median [IQR] gestational age, 39 [38-40] weeks) with maternal IgG antibodies to SARS-CoV-2 detected at the time of delivery were included. IgG was detected in cord blood from 557 of 585 newborns (95.2%). Among 169 vaccinated persons without SARS-CoV-2 infection, the interval from first dose of vaccine to delivery ranged from 12 to 122 days. The geometric mean IgG level among 169 vaccine recipients was significantly higher than that measured in 408 persons after infection (33.88 [95% CI, 27.64-41.53] arbitrary U/mL vs 2.80 [95% CI, 2.50-3.13] arbitrary U/mL). Geometric mean IgG levels were higher after vaccination with the mRNA-1273 (Moderna) vaccine compared with the BNT162b2 (Pfizer/BioNTech) vaccine (53.74 [95% CI, 40.49-71.33] arbitrary U/mL vs 25.45 [95% CI, 19.17-33.79] arbitrary U/mL; P < .001). Placental transfer ratios were lower after vaccination compared with after infection (0.80 [95% CI, 0.68-0.93] vs 1.06 [95% CI, 0.98-1.14]; P < .001) but were similar between the mRNA vaccines (mRNA-1273: 0.70 [95% CI, 0.55-0.90]; BNT162b2: 0.85 [95% CI, 0.69-1.06]; P = .25). Time from infection or vaccination to delivery was associated with transfer ratio in models that included gestational age at delivery and maternal hypertensive disorders, diabetes, and obesity. Placental antibody transfer was detectable as early as 26 weeks' gestation. Transfer ratio that was higher than 1.0 was present for 48 of 51 (94.1%) births at 36 weeks' gestation or later by 8 weeks after vaccination.

CONCLUSIONS AND RELEVANCE

This study found that maternal and cord blood IgG antibody levels were higher after COVID-19 vaccination compared with after SARS-CoV-2 infection, with slightly lower placental transfer ratios after vaccination than after infection. The findings suggest that time from infection or vaccination to delivery was the most important factor in transfer efficiency.

Global Perspectives on Immunization Against SARS-CoV-2 During Pregnancy and Priorities for Future Research: An International Consensus Paper From the World Association of Infectious Diseases and Immunological Disorders

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pregnancy is associated with a higher risk for severe morbidity and mortality when compared with infection in non-pregnant women of childbearing age. An increasing number of countries recommend immunization against SARS-CoV-2 in pregnant women. Recent studies provide preliminary and supportive evidence on safety, immunogenicity and effectiveness of coronavirus disease 2019 (COVID-19) vaccines in pregnant women; however, important knowledge gaps remain which warrant further studies. This collaborative consensus paper provides a review of the current literature on COVID-19 vaccines in pregnant women, identifies knowledge gaps and outlines priorities for future research to optimize protection against SARS-CoV-2 in the pregnant women and their infants.

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.