Why is this important?
RSV is a common cause of lower respiratory infection and exacerbations of comorbidities that can jeopardize the prognosis in the elderly. Several formulations of candidate vaccines have been evaluated in phase 1-2 trials and have shown satisfactory safety profiles, as well as the production of neutralizing antibodies in the elderly. The RSVPreF3 OA formulation adjuvanted with AS01E was chosen to be tested in a first phase 3 trial because of its less reactogenic properties.
Methodology
Subjects aged 60 and over were recruited in 17 countries on different continents of the world. Those suffering from chronic pathologies might be included if their pathology was stabilized. Participants were then randomized 1:1 to receive a placebo or a single dose of the RSVPreF3 OA vaccine candidate. This targets the RSV pre-fusion protein F which is involved in the fusion of the viral membrane with that of the host cells. The objective was to demonstrate the efficacy of this vaccine once morest RSV lower respiratory infections during a winter epidemic, these infections having to be confirmed by RT-PCR. The results published in the New England Journal of Medicine report the first results of the trial which is still in progress.
Principle results
Nearly 25,000 subjects were included. The average age of the participants at inclusion was 69.5 years and 39% of them suffered from pathologies likely to increase the risk of a severe form in the event of RSV infection.
After a median follow-up of 6.7 months, vaccine efficacy once morest RSV lower respiratory infections was 82.6%. [57,9-94,1] (7 cases in the vaccinated group and 40 in the control group), and the efficacy criterion might be deemed to have been achieved (low value of the CI >20%). Efficacy was maintained regardless of age group (60-69 or 70-79 years).
The efficacy of the vaccine once morest severe forms of RSV lower respiratory infections was 94.1% [62,4-99,9] and it was still 71.7% [56,2-82,3] once morest all RSV acute respiratory infections.
Efficacy once morest RSV lower respiratory infections was similar for virus strains A and B and correlated with the production of neutralizing antibodies once morest both strains.
It was maintained in the presence of comorbidities (94.6%), including in those with a pre-fragile status (92.9%) (not assessed in fragile subjects due to too few cases).
Injection reactions were more common in the vaccine group than in the placebo group, but most were transient. Furthermore, the incidence of serious adverse events (4.2% and 4.0% respectively) and of potential immune system-related diseases was similar in the 2 groups (0.1% and <0.1% respectively).
Limits
The authors of the test are employees of the GSK laboratory.
