“A subset of these women had this very high IgG4 and low IgG1 response, and this suggests a Th2/Treg influence. This unique isotype profile was not found in any nonpregnant women,” she said, adding that very few pregnant women in their second or third trimester make the high IgG1/low IgG4 that should provide a good response to flu vaccine.
Although Dr. Schlaudecker acknowledged that 80%-90% of the pregnant women in the study had protective HAI titers after immunization, she said the findings have important implications.
“I’m concerned that these low IgG1/high IgG4 ratios seen in pregnant women might actually be giving poor protection against flu infection, which brings us back to the pediatric patients. If pregnant women are not protected well, we are not protecting the babies as well. This suggests that we might need to reconsider approaches to timing of flu vaccine or actually the particular vaccines that we give to pregnant women, and it also shows that pregnancy likely effects systemic responses to things like flu vaccine and other vaccines,” she said.
Dr. Schlaudecker reported having no disclosures.