RSV vaccine shows high efficacy in older adults

19th October 2022

An RSV vaccine provided a high overall efficacy in older adults especially among patients with a severe lower respiratory tract infection

RSV vaccine candidate, RSVPreF3, manufactured by GSK, provided a high overall efficacy in a phase 3 trial among older adults.

Respiratory syncytial virus (RSV) is one of the common viruses that cause coughs and colds and causes severe respiratory illnesses in infants and older adults who frequently require hospitalisation.

The condition creates a severe disease burden upon sufferers and the global number of hospital admissions for RSV-acute respiratory infections (ARI) in older adults has been estimated at 336,000, leading to an estimated 14 000 in-hospital-related deaths.

Currently, no RSV vaccine has been approved although in September 2022, it was reported that Pfizer was ready to file for FDA approval of its candidate RVS vaccine.

GSK’s randomised, placebo-controlled trial was designed to evaluate the efficacy of the RSVPreF3 at preventing lower respiratory tract disease (LRTD) caused by RSV in adults ≥ 60 years of age following a single dose of the vaccine.

GSK announced preliminary findings from the study in June 2022, including that the vaccine showed statistically significant and clinically meaningful efficacy in adults aged 60 years and above. The current findings have yet to be published in a peer-reviewed article.

RSV vaccine results

The findings show that among those assigned to RSVPreF3 there were seven lower respiratory tract RVS cases compared to 40 in the placebo group, giving an overall vaccine efficacy of 82.6% (96.95% CI, 57.9 – 94.1, p < 0.0001). The vaccine also demonstrated a high efficacy against both type A (84.6%) and type B (80.9%) RVS.

In addition, there was a consistently high vaccine efficacy across a range of pre-specified secondary endpoints. For example, among those with a severe lower respiratory tract infection, there was only one case in the RSV vaccine group compared to 17 in the placebo arm, giving an efficacy of 94.1% (95% CI, 62.4 – 99.9, p < 0.0001). Among patients with pre-existing comorbidities, such as underlying cardiorespiratory and endocrino-metabolic conditions, vaccine efficacy was 94.6% (95% CI, 65.9 – 99.9) and 93.8% (95% CI, 60.2-99.9) in adults aged 70-79 years.

Among patients with RSV confirmed acute respiratory infections, vaccine efficacy whilst lower, was still high with an overall efficacy of 71.7% and again, this was similar for type A (71.9%) and type B (70.6%).

The RSV vaccine was also well tolerated with observed solicited adverse events typically mild-to-moderate in severity and transient, with the most frequent being injection site pain, fatigue, myalgia, and headache.

The company expects to undertake regulatory submissions based on the phase III data in the second half of 2022.