Pregnant and breastfeeding women generate a weaker immune response after their first COVID-19 dose relative to nonpregnant women of similar ages, according to a recent study published in Science Translational Medicine.
Researchers evaluated the antibody response among 84 pregnant women, 31 women who were breastfeeding and 16 nonpregnant women who received Pfizer or Moderna's mRNA vaccines. Participants were sampled after their first or second doses, with a subset sampled after each of the doses.
Pregnant and breastfeeding women had fewer antibodies than other women of the same age after their first dose, the findings showed. Those antibodies were also less effective at kickstarting other parts of the immune system to ward off the virus.
Two to six weeks after the second dose, however, pregnant and breastfeeding women had about the same level of antibodies of their nonpregnant counterparts.
"The authors found that two doses of vaccine were required for pregnant or lactating women to achieve immune responses comparable to that of nonpregnant women," the Oct. 19 study said.