How does pregnancy influence the effectiveness of the COVID-19 vaccine?

After receiving two doses, the immune response of pregnant and nursing women becomes as strong as that of the general population. A recent study found that messenger RNA–based COVID-19 vaccinations generate a substantial antibody response in those who receive both of the necessary shots (Sci. Transl. Med. 2021, DOI: 10.1126/scitranslmed.abi8631). This is good news for pregnant and nursing women. The immune system changes during pregnancy and nursing because if it reacts too forcefully, the body will reject the growing foetus. However, the system must also protect the newborn from infection and pass on immunity. Andrea Edlow of Harvard Medical School and colleagues studied the quantities of protective antibodies developed after exposure to COVID-19 vaccinations to see how these alterations in the immune system would affect the vaccine's effectiveness. The researchers discovered that while pregnant and breastfeeding women produced fewer protective antibodies than a control group after the first vaccine dosage, the difference vanished after the second dose. Because antibodies are passed down through the placenta and human milk, vaccinations given during pregnancy may help protect the newborn. Researchers discovered changes based on the gender of the foetus in a second study (Sci. Transl. Med. 2021, DOI: 10.1126/scitranslmed.abi7428). People carrying male babies had fewer antibodies and transmitted fewer antibodies across the placenta after SARS-CoV-2 infection than those carrying female foetuses.