Investigational RSV Vaccine Found to be Immunogenic

Respiratory Syncytial Virus (RSV) is commonly seen in infants and can be a reoccurring medical issue in seniors while only supportive treatment is available And during the age of the COVID-19 pandemic, this can exacerbate treatment challenges.

Investigators in Belgium and the United States studied an RSV vaccine in adults in phase 1/2 randomized clinical trial and was found to be immunogenic.

The investigational vaccine was GlaxoSmithKline’s RSVPreF3, and looked at 2 cohorts. In the first they had people ages 18–40 years who were randomized to receive 2 doses of either a low, medium or high-dose of the non-adjuvanted vaccine or placebo, being administered 2 months apart.

After the vaccine was found to have favorable safety profiles in the first cohort, the second cohort participants aged 60–80 years were randomized in a 2-step staggered manner to receive 1 of the 9 RSV vaccine formulations containing low, Medium, or high dose of RSVPreF3, non-adjuvanted or adjuvanted with AS01E or AS01B, or placebo also with 2 months apart. Immune responses were assessed before and after each dose; results up to 1 month post-dose 1 are shown here.

“Of 48 adults aged 18–40 years and 1005 aged 60–80 years included in the exposed set, 42 and 933, respectively, were part of per-protocol set at 1 month post-dose 1,” the investigators reported. “RSVPreF3 IgG geometric mean antibody concentrations were 8.4–13.5 and 7.2–12.8 fold-higher at 1 month post-dose 1 vs baseline in the 18–40- and 60–80-year-old vaccines, respectively. RSV-A neutralization activity significantly increased in all RSV vaccines, geometric mean antibody titers being 7.5–13.7 and 5.6–9.9 fold-higher in 18–40- and 60–80-year-olds, respectively, at 1 month post-dose 1 vs baseline.”

A robust RSVPreF3-specific CD4+ T-cell response was elicited at 1 month post-dose 1 vs baseline in both 18–40- and 60–80-year-olds

“One dose of RSVPreF3 candidate vaccine boosted humoral and cellular immune responses in all vaccines,” the investigators noted. “In older adults, higher humoral response, mostly neutralizing, was observed with increased RSVPreF3 antigen dosage and a tendency of higher cellular response was observed after adjuvanted formulations.”

The study, A Respiratory Syncytial Virus Prefusion F Protein (RSVPreF3) Candidate Vaccine Administered in Older Adults in a Phase I/II Randomized Clinical Trial Is Immunogenic was presented as a virtual oral abstract at IDWeek 2020.