By IDSE News Staff
Receiving a COVID-19 mRNA vaccine or booster during pregnancy can benefit the parent and the newborn (Vaccine 2023;41[36]:5296-5303).
The MOMI-VAX study was launched in June 2021 when data on COVID-19 vaccination in pregnant people were sparse. Researchers hoped to understand the immune response after receipt of the Pfizer-BioNTech and Moderna COVID-19 vaccines, and determine how much protection they provided against illness.
The chances of hospitalizations and deaths from severe COVID-19 are higher during pregnancy. COVID-19 also increases in the risk for preterm births. Researchers also suspected that, as with other vaccines, the antibodies generated by COVID-19 vaccination might transfer to fetuses across the placenta, which would provide newborns with some additional protection against COVID-19 in their first months of life. Among other metrics, the study tracked the COVID-19 antibody levels of pregnant people who received either of the two COVID-19 vaccines, as well as the antibodies in their cord blood when they gave birth.
Researchers at the National Institute for Allergy and Infectious Diseases—funded Infectious Diseases Clinical Research Consortium followed more than 500 pregnant volunteers and their newborns at nine study sites. Results from 240 participants are reported in the paper, including 167 pregnant participants who received the two-dose primary series of either of the two mRNA vaccines during pregnancy and 73 who received a booster dose; at the time, only one booster dose was recommended. Researchers examined blood samples taken before and after participants were vaccinated or boosted, and at the time of delivery.
The researchers also analyzed participants’ cord blood at the time of birth.
The researchers found that pregnant people who received the COVID-19 vaccines generated antibodies against specific types of SARS-CoV-2. These included antibodies against the D614G variant, which the vaccines were designed to protect against, as well as the delta and omicron variants and their subvariants. The antibodies effectively crossed the placenta and were found in the cord blood of vaccinated participants. This factor likely conferred some protection in the newborns against these variants immediately after birth—a critical time when they are vulnerable to severe COVID-19 disease but are too young to be vaccinated, according to the researchers.
Pregnant participants who received a booster dose had substantially more antibodies against SARS-CoV-2, both in their own blood and in their cord blood, suggesting that boosting also increased their newborns’ immune defenses against COVID-19. These findings support the use of COVID-19 vaccination, particularly the booster doses, during pregnancy for protection of pregnant people and their newborns.
The researchers suggest that future studies could determine the best time during pregnancy to get vaccinated against COVID-19 to provide the most protection for pregnant people and their newborns. In addition, researchers hope to build a more complete picture of how prenatal COVID-19 vaccination affects infants using more data collected during the MOMI-VAX study, such as antibody levels in breast milk and infants’ SARS-CoV-2 antibody levels in the year after birth.
