Moderna mRNA RSV vaccine proves effective for older adults

Editor’s note

Moderna’s mRNA-based RSV vaccine is effective in preventing RSV-associated lower-respiratory tract disease in adults aged 60 an older, according to randomized phase II-III trial results published December 14 in The New England Journal of Medicine. Results also confirmed the safety of a single dose of the vaccine, researchers report. Highlights include:

• Of the study’s 35,541 participants, roughly half (17,748) received a placebo, and the remained received the mRNA-based RSV vaccine, mRNA-1345 (encoding the stabilized RSV prefusion F glycoprotein).
• After a median follow-up of 112 days, vaccine efficacy was 83.7% (95.88% confidence interval [CI], 66.0 to 92.2) against RSV-associated lower respiratory tract disease with at least two signs or symptoms and 82.4%  (96.36% CI, 34.8 to 95.3) against the disease with at least three signs or symptoms.  
• Vaccine efficacy was 68.4% (95% CI, 50.9 to 79.7) against RSV-associated acute respiratory disease.
• The vaccine protected against both RSV A and B subtypes.

As for safety, participants in the mRNA-1345 group had a higher incidence than those in the placebo group of solicited local adverse reactions (58.7% vs. 16.2%) and of systemic adverse reactions (47.7% vs. 32.9%). Most reactions were transient and mild to moderate in severity. Serious adverse events occurred in 2.8% of the participants in each trial group.

Phase I of the clinical efficacy trial, ConquerRSV, also did not reveal safety concerns, and results showed immunogenicity in younger and older adults. Follow-up is ongoing to determine the duration of protection afforded by the vaccine as well as the appropriateness and timing of a booster dose.