Maternal vaccination with a single dose against RSV gave rise to a high efficacy against severe infection among infants.
RSV infection leads to a global high morbidity and mortality burden in children aged 0-60 months. Moreover, the greatest risk for hospitalisation occurs during the first six months of life.
In a recent study, RSV-associated acute respiratory infection, led to the hospitalisation of one in every 56 healthy term-born infants. Whether maternal vaccination can reduce such RSV-related infection in newborns and infants remains uncertain.
In the present, randomised, double-blind, phase 3 trial, pregnant women received a single dose vaccine or placebo, between weeks 24 and 36. The two primary efficacy endpoints were severe RSV-associated lower respiratory tract illness and medically attended, less severe illness. Assessment of these outcomes took place at 90 and 180 days after birth. A lower boundary of the confidence interval > 20% was the success criterion for vaccine efficacy.
Maternal vaccination and RSV-associated infections
Overall, 7,358 women received either the vaccine (3682) or placebo. There were six cases of severe RSV in the vaccinated group and 33 in the placebo arm within 90 days of birth (vaccine efficacy = 81.8% 99.5% CI 40.6% – 96.3%). Within 180 days, the vaccine efficacy against severe infection was 69.4% (97.58% CI 44.3 – 84.1%).
In contrast, vaccine efficacy was only 57.1% (99.5% CI 14.7 – 79.8) against less severe disease and did not meet the criteria for success.
Adverse events were similar in all groups within one month after injection or within one month after birth.
