Pregnancy Changes Immune Response to Covid Shot, Study Says

(Bloomberg) -- Pregnant and breast-feeding women appear to respond relatively weakly to their first dose of Covid-19 vaccines, according to a study that indicates the importance of them receiving both doses of standard regimens.

Immune responses to a single dose of vaccines from Moderna Inc. and Pfizer Inc. and BioNTech SE were weaker than in a group of nonpregnant women, according to the study released Tuesday by Science Translational Medicine. Though all participants developed Covid antibodies against Covid-19, other immune responses, like antibody receptor functions, only reached standard levels after their second dose, 

Studies have shown that pregnant women are particularly vulnerable to Covid symptoms. Some people have avoided the shots because of concerns, largely discounted by research, about fertility and breast feeding.

“These results imply that vaccination earlier in pregnancy and boosting later in pregnancy will help to maximize transplacental and breastmilk antibody transfer,” Cristian Ovies and colleagues from Duke University School of Medicine, who weren’t involved in the study, said in a related editorial in the journal. 

A second study released by the same journal suggested that women pregnant with male fetuses responded with fewer virus-fighting antibodies and other immune changes than those with female fetuses. More such research is needed to understand women’s response to Covid and vaccination, Ovies and  colleagues said in the commentary.

“These studies echo the call-to-action to incorporate women at different stages of gestation into clinical trials,” the researchers said, “thereby increasing their representation in the development of vaccines.”

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