Rsv vaccine moderna

The short version: Moderna's RSV vaccine, mRESVIA, showed about 83% efficacy against RSV-LRTD in its Phase 3 trial, but that protection wanes to roughly 50% by 18 months, and the safety evidence comes from the manufacturer's own funded trial with no long-term comparison against an unvaccinated group.

The ConquerRSV trial, funded by Moderna, reported 83.7% efficacy against RSV-LRTD (lower respiratory tract disease with two or more symptoms) and 82.4% against cases with three or more symptoms in adults 60 years and older [1]. The evidence also shows this protection is not durable: efficacy dropped to about 50% against the same endpoint at 18 months, though protection against severe disease held up better [1]. The trial reported only "mild to moderate transient adverse events" with no signals for myocarditis or Guillain-Barré syndrome (GBS), but this is based on a single manufacturer-run trial [1].

Several questions remain unanswered by this evidence. The ConquerRSV trial compared the vaccinated group to a placebo group during the blinded phase, but no data is presented on long-term safety beyond the trial period or outcomes in a truly untreated comparison group after unblinding. The review also notes that revaccination may be needed to sustain protection, which raises questions about cumulative safety from repeated doses [1]. The GBS signal was discussed in the context of the other approved vaccines, but the Moderna trial itself did not have enough participants to detect rare events [1].

My call: mRESVIA shows meaningful short-term benefit against symptomatic RSV, but its protection fades quickly and the safety data is limited to a single manufacturer's trial without long-term follow-up against an unvaccinated group. Confidence: low — the evidence is too thin on durability and long-term safety for a confident recommendation.