Published onVaccine Update for Healthcare Providers
Each year in the United States, 3% to 7% of adults greater than 65 years of age are symptomatically infected with respiratory syncytial virus (RSV). These infections result in approximately 175,000 hospitalizations and 14,000 deaths. Therefore, it would be reasonable to develop an RSV vaccine for this at-risk population.
Toward this end, researchers at Pfizer laboratories have developed a bivalent RSV vaccine consisting of the prefusion F protein from subgroups A and B. This vaccine has now been tested in a phase 2a study in adults 18-50 years of age (Schmoele-Thoma B, Zareba AM, Jiang Q, et al. Vaccine Efficacy in Adults in a Respiratory Syncytial Virus Challenge Study. New Engl J Med. 2022. June 23;386(25):2377-2386). Seventy healthy adults were divided into two groups. One group received a single dose of RSV vaccine intramuscularly, and the other group received placebo. Twenty-eight days later, both groups were challenged with an intranasal dose of 4.5 log10 plaque-forming units of RSV A Memphis 37b. The authors found that shedding of the challenge virus was markedly reduced in the vaccine group and that vaccine efficacy against clinically apparent illness was 86.7%. Although more local injection-site events were noted in the vaccine group, no serious adverse events occurred.
The authors concluded, “RSVpreF vaccine was effective against symptomatic RSV infection and viral shedding.”
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