Respiratory syncytial virus (SCV) is a major cause of lower respiratory tract infections in newborn infants. While RSV can be controlled with non-particle vaccination, its effect on newborn infants is unclear. The objective of the study is to evaluate the association between RSV vaccination during pregnancy and lower respiratory tract infections in infants. 

This is a randomized trial study in which 4,636 healthy pregnant women went under randomization. All the participating women were at 28-36 weeks of gestation with the excepted delivery date near the beginning of the RSV season. The women were divided into two groups (2:1), women in one group were assigned RSV fusion nanoparticle vaccine, and others were assigned placebo. The researchers followed the infants for 90 days to assess the outcomes.

Out of 4,636 women, 4,579 were live births. During the first 90 days of life, 1.5% of infants from the vaccine group had lower respiratory tract infections, compared to 2.4% in the placebo group. The percentages of hospitalization for vaccine and placebo groups were 2.1% and 3.7%, respectively.

The research concluded that the RSV F nanoparticle vaccine did in pregnant women did not meet the efficiency criteria against RSV-related lower respiratory tract infection in newborn infants.