Antibody titers higher in moms infected with SARS-CoV-2 then boosted during pregnancy
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Women with COVID-19 during pregnancy who subsequently received one mRNA vaccine dose had the highest levels of antibodies at delivery compared with infected, unvaccinated women and vaccinated women who were never infected.
Similar levels were observed in umbilical cord blood, which other studies have shown promotes newborn protection.
According to the researchers, pregnant patients in Israel who had a SARS-CoV-2 infection were recommended to receive a single Pfizer-BioNTech dose 3 months after infection “in light of the declining antibody titers among recovering COVID-19 patients, along with the evidence that boosting improves cross variant immunization.”
“This unique population of convalescent pregnant patients, who received mRNA vaccine boosting, presents a rare opportunity to describe for the first time the effect of this immunization during pregnancy,” Lea Nevo, MD, a doctor in the department of OB/GYN at Hebrew University of Jerusalem Hadassah Medical Center in Israel, and colleagues wrote. “Such data are especially needed, as accumulating research supports the notion that pregnancy is a time of immune system modulation, affecting many aspects of the maternal immune response, including the humoral response.”
Nevo and colleagues prospectively collected serum samples from pregnant women and umbilical cords at delivery at Hadassah Medical Center between May and October 2021. Using samples from 228 parturients aged 18 to 45 years, the researchers compared SARS-CoV-2 antibody levels among 54 women with convalescent infection, 60 women with convalescent infection who received one Pfizer-BioNTech dose as a booster and 114 women who did not have a prior SARS-CoV-2 infection but had received two doses of the Pfizer-BioNTech vaccine.
Data showed that there was a “gradual and significant decline” in SARS-CoV-2 antibody titers between infection and delivery, with 34.6% and 9.1% of women infected in the first and second trimesters, respectively, testing negative for antibodies at delivery.
Women with convalescent infection who received a booster dose had 17.6-times greater levels of antibodies compared with those who did not receive a booster. They also had 3.2-times greater levels of antibodies compared with vaccinated, infection-naive women.
Analyses of umbilical cord blood revealed that antibody titers were higher in the boosted convalescent group than in the vaccinated, infection-naive group and the unvaccinated, convalescent group.
Side effects of vaccination were mild across groups, although boosted convalescent women had significantly lower rates of myalgia, injection site pain and malaise.
“Given the observed decline in antibody levels before and during pregnancy, boosting strategies to enhance maternal and newborn anti-SARS-CoV-2 immunity may become the standard of care in the ongoing battle against novel variants,” Nevo and colleagues wrote. “In this context, our work provides essential data to answer key questions that clinicians encounter on a daily basis, and support policy makers when deliberating the benefits of vaccine boosting in convalescent pregnant patients.”