Last week, the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC), on separate days, recommended approving Pfizer’s PFE and GSK’s GSK respective respiratory syncytial virus (RSV) vaccines.

Both companies seek FDA approval for the use of their respective vaccines to prevent lower respiratory tract disease (LRTD) caused by RSV in older adults (aged 60 years and above). With the FDA granting priority review to the regulatory filings for both vaccines, a final decision on both vaccines is expected in May 2023.

While the VRBPAC voted 7-4 on both the safety and effectiveness of Pfizer’s vaccine, the GSK vaccine secured a unanimous recommendation from the VRBPAC on effectiveness and 10 to 2 on safety.

The VRBPAC decisions are based on data from pivotal studies which evaluated these vaccines. The data supporting GSK’s vaccine showed overall vaccine efficacy of 82.6% against RSV-LRTD, while the Pfizer vaccine achieved vaccine efficacy of 85.7% against RSV-LRTD, as defined by three or more symptoms of the disease.

The FDA takes the decision of its advisory committees into consideration but is not bound to follow them.If approved, either Pfizer’s or GSK’s vaccine will be the first approved RSV vaccine in the United States.

Apart from Pfizer and GSK, Moderna MRNA is also evaluating its own RSV vaccine candidate. Earlier this year, Moderna announced that the FDA had granted breakthrough therapy designation to mRNA-1345, its own RSV vaccine candidate, to prevent RSV-LRTD in older adults. The decision was based on data from a late-stage study wherein participants who were administered the vaccine achieved more than 80% efficacy against RSV-LRTD. Based on these results, Moderna plans to submit for regulatory approval of mRNA-1345 in first-half 2023.

Pfizer and Moderna are also evaluating their vaccine for use in other patient populations. Last month, Pfizer announced that the FDA had accepted the regulatory filing to seek expanded use of its RSV vaccine to prevent LRTD caused by RSV in infants from birth up to six months of age by actively immunizing pregnant individuals. A decision is expected later this year in August.

Moderna is evaluating mRNA-1345 in an early-stage study in pediatric populations.

Currently, there are no FDA-approved vaccines against RSV infections. Older adults are at maximum risk of getting RSV disease. The LRTD-RSV disease causes a high morbidity and mortality rate in older adults and young kids.

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