Dr. Prabhu and her colleagues set up the new study to address the question of the best timing for COVID-19 vaccination during pregnancy. The analysis covered 1,359 pregnant women who reported vaccination against COVID-19, during or up to six weeks before pregnancy, and gave birth at NewYork-Presbyterian Alexandra Cohen Hospital for Women and Newborns after 34 or more weeks of gestation.
They found that anti-spike antibodies were generally detectable at delivery, in maternal and cord blood, among all the fully vaccinated women, regardless of the timing of their first vaccine dose. Among women with no history of SARS-CoV-2 infection who received the two-dose Pfizer or Moderna mRNA vaccine, the levels of antibodies at delivery were lowest after pre-pregnancy or first trimester vaccination and highest after third trimester vaccination; however, the difference wasn’t large. There was no significant difference in anti-spike antibody levels by timing of vaccination among the relatively small number of women who received the Johnson & Johnson (J&J) single-dose vaccine.
Among vaccinated women who had a prior history of COVID-19 infection, anti-spike antibody levels at delivery in maternal and cord blood were moderately higher on average, and showed even less of a decline with earlier vaccination timing.
Twenty of the women reported having a booster dose in the third trimester, and on average they had still higher levels of anti-spike antibodies in maternal blood and in cord blood.
In women who did not receive a complete course of vaccination by time of birth, the levels of anti-spike antibodies in maternal blood and in cord blood were significantly lower than all other cohorts including the earliest vaccinated cohort.
The findings suggest that pregnant women should not delay until late pregnancy COVID-19 vaccination.
“The message here is that you can get vaccinated at any point during pregnancy and it is likely going to be beneficial to you and your baby at the time of birth — and of course by getting vaccinated early, you will be protecting yourself and your baby throughout the pregnancy,” says first author, Dr. Yawei Jenny Yang, assistant professor of pathology and laboratory medicine at Weill Cornell Medicine and a pathologist at NewYork-Presbyterian/Weill Cornell Medical Center.
“These study results are consistent with what we see with other maternal vaccines, such as flu and Tdap, which, when given during pregnancy, protect the mother and baby,” says senior author, Dr. Laura E. Riley, chair of the Department of Obstetrics and Gynecology at Weill Cornell Medicine and obstetrician and gynecologist-in-chief at NewYork-Presbyterian/Weill Cornell Medical Center.
The researchers now plan further studies to examine vaccine and booster effects under different maternal conditions and in the context of the spread of the new Omicron variant of SARS-CoV-2.
A version of this article first appeared on Weill Cornell Medicine’s newsroom.