THURSDAY, Nov. 21, 2024 (HealthDay News) — Respiratory syncytial virus (RSV) vaccination at least five weeks prior to delivery results in the highest transplacental transfer of maternal antibodies to the neonate, according to a study published online Nov. 6 in the American Journal of Obstetrics & Gynecology.

Olyvia J. Jasset, from the Vincent Center for Reproductive Biology at Massachusetts General Hospital in Boston, and colleagues examined how gestational age at vaccination and time elapsed from maternal RSV vaccination to delivery impacts transfer of maternal antibodies measured in the umbilical cord at delivery and in peripheral blood of infants aged 2 months in a prospective cohort study enrolling 124 individuals who received the RSV vaccination during pregnancy.

The researchers found that compared with natural infection, maternal RSV vaccination resulted in significantly higher maternal and cord anti-RSV F antibody levels. Significantly lower cord:maternal transfer ratios were seen in association with maternal vaccination two to three and three to four weeks prior to delivery versus more than five weeks prior to delivery; similarly, for pertussis vaccination administered prior to 30 weeks of gestation, transfer ratios were significantly lower at two to three or three to four versus more than four weeks prior to delivery.

“The finding of optimal transplacental transfer of maternal antibody at ≥5 weeks postvaccination may inform future evaluations of vaccine timing,” the authors write.

Two authors disclosed ties to the pharmaceutical industry.

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