Maternal RSV vaccination and infant nirsevimab immunization found safe and effective

Maternal respiratory syncytial virus (RSV) vaccination and infant nirsevimab immunization, administered alone or sequentially, are safe and effective, according to a study published online May 4 in Pediatrics.

Christina A. Rostad, M.D., from the Emory University School of Medicine in Atlanta, and colleagues conducted a randomized, open-label phase 4 study at eight U.S. sites of mother-infant pairs to examine administration of maternal RSV prefusion F vaccination (RSVpreF) and infant nirsevimab immunization. Pairs were randomly assigned during pregnancy to receive maternal RSVpreF vaccine alone, maternal RSVpreF vaccine/infant nirsevimab at birth, maternal RSVpreF vaccine/infant nirsevimab at 3 months, or infant nirsevimab alone at birth. To ascertain safety, infant tolerability, and the magnitude and durability of RSV-A and B neutralizing antibodies (nAbs), pairs were followed for 12 months.

One hundred eighty-one mothers were enrolled in the study. The researchers found that both products alone and in combination were safe, with no related serious adverse events in mothers or infants. Nirsevimab was well tolerated; all local and systemic reactogenicity was mild to moderate. Maternal RSV-A nAb titers were boosted 17.35-fold at the time of delivery by RSVpreF vaccination; titers were durable through three months after delivery. The geometric mean transfer ratio of RSV-A nAbs exceeded 1.3 and was similar across the groups. Irrespective of group, RSV nAbs were highly elevated in infants at six weeks and three months, with modest differences seen in waning.

“While most infants will not need to receive both products to be protected, our results suggest that maternal RSV vaccination and infant nirsevimab immunization may be safely sequentially administered,” the authors write.

Several authors disclosed ties to the biopharmaceutical industry.

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