OR WAIT null SECS
Early Microbiome Shifts May Define a Critical Window for Allergy Risk, With Jose Clemente, PhD
Early gut microbiome changes in c-section infants linked to food sensitization at 12 months, highlighting a potential critical intervention window.
New ACTIVATE data found that vaginal seeding in cesarean-delivered infants was associated with altered early gut microbiome patterns and differences in food sensitization at 12 months.
Jose Clemente, PhD, associate professor of genetics and genomics and immunology at the Icahn School of Medicine at Mount Sinai, presented these late-breaking findings at the 2026 American Academy of Allergy, Asthma, & Immunology (AAAAI) in Philadelphia from February 27 to March 2. ACTIVATE, a double-blind, randomized trial, evaluated whether exposure to maternal vaginal microbiota at birth can influence food allergen sensitization in cesarean-delivered infants at high risk for allergic disease.
The study enrolled 39 vaginally delivered infants, 37 cesarean-delivered infants who received placebo seeding, and 37 cesarean-delivered infants who underwent vaginal seeding, along with their mothers. Vaginal seeding in the study involved placing sterile gauze in the maternal vagina approximately 1 hour before cesarean delivery, and then immediately after birth, using the gauze to swab the infant’s mouth, face, and body.
ACTIVATE showed that Lactobacillus, abundant in maternal vaginal samples, was enriched in the stool of infants who received vaginal microbial transfer compared with placebo immediately after birth (P =.002). At 3 months, infants who underwent vaginal seeding had stool microbiomes more similar to vaginally delivered infants than placebo-treated infants (similarity 0.876 ± 0.07 vs 0.9 ± 0.06; P =.169); this effect was partial and waned over time. The analysis also showed that maternal vaginal microbiome composition itself was not associated with food sensitization at 12 months (P =.86), but specific infant gut microbes identified at 12 months were associated with allergen sensitization (Rothia mucilaginosa with egg, Bifidobacterium breve with milk, and Ruminococcus gnavus with egg, milk, and peanut.
In an interview with HCPLive during AAAAI, Clemente emphasized that even temporary microbial shifts may influence long-term immune trajectories.
“We see differences for the first few months, but then after a while, those differences, at least looking at the microbes…disappear,” Clemente said. “It doesn't matter if you've been exposed to the microbes or not when the babies are 1 year of age. We don't see differences anymore, but we think it's really those first few months when it’s critical to intervene if we want to lower [allergy] risk. I think a harder problem that comes out of it is, well, what happens if you have a child that already has an allergy? That's a much harder problem to tackle because we know that it's during these first few months when we can modulate the microbiome and modulate the immune development based on those interventions.”
Clemente has no relevant disclosures.
References
