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Background: In this phase 3 trial of an investigational maternal respiratory syncytial virus prefusion F protein-based vaccine (RSVPreF3-Mat), a higher rate of preterm birth was observed in the vaccine (6.8%) versus the placebo group (4.9%). Trial enrollment and vaccination were stopped. Results of investigations into this safety signal were reported previously. Here, we describe end-of-trial efficacy, immunogenicity, and safety results., Methods: Women 18-49 years old were randomized 2:1 to receive one dose of RSVPreF3-Mat (n=3557) or placebo (n=1771) at 240/7-340/7 weeks' gestation. Primary outcomes were any and severe medically assessed RSV-associated lower respiratory tract disease (MA-RSV-LRTD) in infants until 6 months post-birth and safety until 12 months post-birth. Other efficacy outcomes were evaluated, along with immunogenicity (until 6 months post-partum/birth) and safety in mothers and infants., Results: Efficacy in infants until 6 months post-birth was 65.5% (95% credible interval: 37.5-82.0) against any MA-RSV-LRTD, 69.0% (33.0-87.6) against severe MA-RSV-LRTD, and 50.1% (-3.6-75.8) against RSV hospitalization; it waned over time thereafter. Efficacy against MA-RSV-LRTD was 47.8% (-25.8-77.3) in low- and middle-income and 75.9% (46.1-91.5) in high-income countries. RSVPreF3-Mat induced a substantial increase in RSV-A neutralization titers in mothers, with efficient transplacental transfer of antibodies that persisted in infants until at least 6 months post-birth., Conclusion: Consistent with the high titers of transplacentally transferred antibodies, this trial suggests a reduced risk of any/severe MA-RSV-LRTD and RSV hospitalization until 6 months post-birth in infants born to mothers immunized with RSVPreF3-Mat during pregnancy. However, vaccine development was terminated due to an identified preterm birth risk., Trial Registration: ClinicalTrials.gov: NCT04605159., (© The Author(s) 2025. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Bedding dust is a mixture of many components, of which the house dust mite (HDM) allergen, Der p 1, is the most allergenic. There has been little work to investigate the effect of other bedding dust components on HDM sensitisation. The objective of the study was to determine the effect of endotoxin in bedding dust on the allergic response in HDM-sensitised individuals. Twenty-nine house dust mite-sensitised adults were skin prick and allergen patch tested against a sterile solution of their own bedding dust and against a solution containing the same concentration of Der p 1 as the bedding solution for comparison. There was no significant difference in wheal size between the diluted house dust mite solution and the bedding dust in spite of their high levels of endotoxin. Symptomatic subjects had larger, but not statistically significant, responses to commercial house dust mite solution than asymptomatic subjects. Allergen patch test responses were negative in 22/29 of subjects using either bedding dust solutions or comparable diluted house dust mite solutions. An individual's own bedding dust does not appear to contain factors that enhance skin prick test or atopy patch test responses to house dust mites.