Two experimental vaccines have shown strong promise in preventing RSV in older adults in mid-late stage, large-scale clinical trials, further advancing their position in the race to bring the world’s first RSV vaccines to market.
In a Phase III trial funded by GlaxoSmithKline, a single dose of RSVPreF3 OA was well-tolerated and able to prevent RSV-related respiratory infection and disease in adults aged over 60 “regardless of RSV subtype and the presence of underlying coexisting conditions”.
A Phase IIb, proof-of-concept study of an Ad26 .RSV.preF–RSV preF protein vaccine, funded by Janssen Vaccines and Prevention, demonstrated that it induced an immunogenic response and prevented RSV-mediated lower respiratory tract disease in adults aged over 65.
GSK’s trial
In GSK’s trial [link here], nearly 25,000 adults aged over 60 were randomised to receive either a dose of the RSVPreF3 OA vaccine (n=12,467) or placebo (n=12,499).
Following a median follow-up of 6.7 months, vaccine efficacy against RSV-related lower respiratory tract disease was 83% (97% confidence interval), with the data revealing 7 cases in the vaccine group and 40 in the control arm.
Vaccine efficacy hit 94% against severe RSV-related lower respiratory tract disease, and 72% against RSV-related acute respiratory infection, and was found to be similar against both A and B virus subtypes, according to the paper.
The authors noted that vaccine efficacy in participants aged 80 years or above and in those classed as frail needs longer follow-up to be able to determine the effect in these groups.
However, efficacy data in adults aged 70-79 years (94%), in those pre-frail (93%) and in those with co-existing conditions (95%), “implies that the RSVPreF3 OA vaccine may be able to protect vulnerable older adults” they said.
Adverse events observed during the trial were typically mild-to-moderate and transient, resolving in a mean of 1-2 days, and the most frequently reported were injection site pain, fatigue, myalgia and headache.
Pain was the most common injection-site reaction (in 61% versus 9% for placebo), while fatigue was top of the systemic reactions (33% and 16%, respectively).
The vaccine is currently being considered for European approval under an accelerated assessment, with a decision expected in the third quarter of this year.
Janssen’s trial
In Janssen’s trial [link here] , 5,782 adults aged over 65 were randomised 1:1 to receive either the Ad26.RSV.preF–RSV preF protein vaccine or placebo.
Vaccine efficacy was found to range from 80% against preventing severe lower respiratory tract infections to 70% for protection against any RSV acute infection (94.2% confidence interval).
According to the authors, the vaccine was effective across age groups and risk level for severe RSV-mediated lower respiratory tract disease, and the safety profile was acceptable, with most adverse events were mild to moderate in severity.
In a safety subpopulation of 695 participants (348 in the vaccine group and 347 in the placebo group), in which 48% of participants were at increased risk because of chronic cardiac or pulmonary disease, solicited local adverse events were reported by 38% of those who received vaccine and 8.4% of those who received placebo, the most common being injection-set pain or tenderness, which resolved in a median of 1-2.5 days.
Solicited systemic adverse events were recorded for 41% of participants in the vaccine arm and 16% in the control group, the most common being fatigue, headache and myalgia.
The vaccine is now being evaluated in a Phase III development programme.
Both trials were published in the New England Journal of Medicine.