THURSDAY, July 30, 2020 (HealthDay News) — Nirsevimab prevents respiratory syncytial virus (RSV)-associated lower respiratory tract infections in healthy preterm infants, while maternal RSV fusion (F) protein nanoparticle vaccination did not meet the prespecified criterion for efficacy, according to two studies published in the July 30 issue of the New England Journal of Medicine.

M. Pamela Griffin, M.D., from AstraZeneca in Gaithersburg, Maryland, and colleagues randomly assigned healthy infants born preterm to receive a single injection of either nirsevimab or placebo in a 2:1 ratio at the start of an RSV season (969 and 484 infants, respectively). The researchers found that the incidence of medically attended RSV-associated lower respiratory tract infection was significantly lower with nirsevimab prophylaxis (2.6 versus 9.5 percent), as was incidence of hospitalization for RSV-associated lower respiratory tract infection (0.8 versus 4.1 percent).

Shabir A. Madhi, M.B., Ch.B., Ph.D., from the University of Witwatersrand in Johannesburg, and colleagues randomly assigned 4,636 healthy pregnant women at 28 weeks 0 days through 36 weeks 0 days of gestation to receive either a single intramuscular dose of the RSV F protein nanoparticle vaccine or placebo in a 2:1 ratio. The researchers found that the percentages of infants with RSV-associated medically significant lower respiratory tract infection were 1.5 and 2.4 percent in the vaccine and placebo groups, respectively (vaccine efficacy, 39.4 percent; 97.52 percent confidence interval, −1.0 to 63.7) during the first 90 days of life, which did not meet the prespecified criterion for success.

“The results with respect to the other end points of RSV-associated and all-cause respiratory disease in infants suggested potential benefits of maternal RSV vaccination that warrant further study of this strategy,” Madhi and colleagues write.

Several authors from the Griffin study disclosed financial ties to pharmaceutical companies, including AstraZeneca and Sanofi Pasteur, which funded the study; the Madhi study was funded by Novavax.

Abstract/Full Text – Griffin

Abstract/Full Text – Madhi

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