Infectious Disease — Whether it provides lasting protection remains to be seen
by Katherine Kahn, Staff Writer, MedPage Today December 13, 2023
Modernas mRNA-based RSV vaccine was effective at fighting RSV-linked lower respiratory tract illness in adults ages 60 and older, according to results of the randomized ConquerRSV trial.
The mRNA-1345 vaccine was 83.7% effective (95.88% CI 66%-92.2%) in fighting RSV-linked lower respiratory tract illness with no less than two symptoms, and equally effective (82.4%) against lower respiratory tract illness with no less than three symptoms (96.36% CI 34.8%-95.3%), Eleanor Wilson, MD, of Moderna in Cambridge, Massachusetts, and colleagues reported in the New England Journal of Medicine.
Participants who received the mRNA-1345 vaccine reported more systemic negative reactions than the placebo group (47.7% vs 32.9%); the most common were fatigue, headache, myalgia, and arthralgia. Serious adverse events occurred in 2.8% of the participants in both groups, and most reactions were mild to moderate in severity and were transient. Fewer than 0.1% were reported to be linked to the shot.
“This phase II-III efficacy trial showed that a single 50-μg dose of the mRNA-1345 vaccine in adults 60 years of age or older was efficacious against a spectrum of RSV-confirmed respiratory illness. No safety concerns were evident,” Wilson’s team concluded from following the participants for over 3 months.
Topline results of ConquerRSV were announced in January 2023. “At that point, we knew that the trial met both its primary efficacy endpoints. Today’s publication provides further analysis of these data and trial design and affirms that the vaccine was generally well-tolerated in this population,” Wilson told MedPage Today in an email.
The mRNA-1345 vaccine was based on the same mRNA vaccine platform used to develop the SARS-CoV-2 vaccine, the authors wrote. It uses a preF antigen-based approach similar to the 2 non-mRNA vaccines currently licensed for RSV. This approach was chosen because the preF conformation is the primary target of RSV-neutralizing antibodies and is highly conserved across all RSV subtypes.
“The most important consideration will be how much protection an mRNA vaccine provides during subsequent RSV seasons and whether subsequent boosting will be appropriate,” Angela Cohn, MD, and Aron Hall, DVM, MSPH, from the National Center for Immunization and Respiratory Diseases at the CDC in Atlanta, wrote in an accompanying editorial. “Such questions about duration of immunity, along with reactogenicity and cold-chain issues, remain important areas for further evaluation in the implementation of mRNA vaccines.”
“Although no cases were reported among adults 80 years of age or older in the latest analysis, efficacy was maintained with increasing age. … The vaccine also showed efficacy in preventing the clinical spectrum of RSV illness regardless of race, ethnic group, sex, or World Bank geographic region and income level,” Wilson’s team reported.
Cohn and Hall commented that the mRNA-1345 results were generally similar to trial estimates for the 2 currently available RSV vaccines licensed for use in people age 60 and up.
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