The Pfizer/BioNTech and Moderna Covid-19 vaccines are effective in pregnant and lactating women, who can pass protective antibodies to newborns, according to research published Thursday in the American Journal of Obstetrics and Gynecology.The Pfizer/BioNTech and Moderna Covid-19 vaccines are effective in pregnant and lactating women, who can pass protective antibodies to newborns, according to research published Thursday in the American Journal of Obstetrics and Gynecology.