Moderna reported that its vaccine was 50% effective at preventing lower respiratory disease following RSV infection, falling short of numbers reported by GSK and Pfizer heading into the fall, when rates of infection typically pick up.
The vaccine was 50.3% effective at preventing lower respiratory tract disease marked by two or more symptoms, and 49.9% effective at preventing illness marked by three or more symptoms. The data were presented as part of the CDC’s Advisory Committee on Immunization Practices review of the shots, and the group is expected to vote on who should get an RSV shot later Wednesday afternoon.
Last year, the group recommended that adults 60 and older receive a single RSV vaccine shot, using shared clinical decision-making. Vaccine manufacturers this year are hoping for a wider, universal recommendation.
The committee’s recommendations can impact uptake of the vaccines, which have become major products for the drugmakers as they compete with each other in the multibillion-dollar market. Moderna’s update was a disappointment to investors, who drove the stock down about 5% after the data were released.
Compared with last year, the Moderna shot’s efficacy dropped more than 10 percentage points for each of the two disease classifications. Similar drop-offs were seen from both Pfizer and GSK, though both maintained higher efficacy.
Pfizer reported in February that efficacy against less severe lower respiratory tract disease was 55.7% at the end of a second RSV season, compared to 65.1% after the first season. GSK reported that its vaccine was 67.2% effective at preventing lower respiratory tract disease through two seasons, but 56.1% effective when just assessed for the second season.
Jefferies analysts said in a note Tuesday that it was looking for Moderna’s efficacy to not dip below 50%.
“[I]f VE is lower than 50% there could be some [potential] impact to sentiment and perception of durability and/or contracting,” the analysts wrote, given that CDC advisors aren’t voting on how frequently to administer the vaccines.