In a press release on 13th October 2022 GSK plc announced “positive pivotal phase III trial results” for a vaccine candidate against respiratory syncytial virus (RSV). The vaccine is for adults of 60 years and older and is in direct competition with Pfizer’s RENOIR results.  


As we explored in our previous post on Pfizer’s earlier results, RSV is particularly threatening to infants and older adults. It is defined by respiratory symptoms and hospitalises thousands of older adults each year. There are no vaccines in the world for RSV, but Pfizer is also working towards a successful candidate.  

GSK’s candidate 

The AReSVi-006 phase III trial is randomised, placebo-controlled, observer-blind, and multi-country. It investigates the efficacy of a single dose of GSK’s adjuvanted RSVPreF3 OA investigational vaccine in adults aged 60 years and older. The candidate contains a “recombinant subunit prefusion RSV F glycoprotein antigen (RSVPreF3) combined with GSK’s proprietary AS01E adjuvant.” Across 17 countries around 25,000 participants were involved in the trial.  

The vaccine candidate is described as “highly efficacious” against RSV-lower respiratory tract disease (LRTD) with overall vaccine efficacy of 82.6%, meeting the trial’s primary endpoint. Furthermore, consistent high efficacy was observed across a “range of pre-specified secondary endpoints”. This efficacy against LRTD was reportedly “consistent” for both RSV-A and RSV-B subtypes. The trial will continue to evaluate “an annual revaccination schedule and longer-term protection” throughout the year.  

It was “well tolerated” and demonstrated a “favourable safety profile”. Adverse effects range from injection site pain to fatigue and a headache but remained “typically mild-to-moderate and transient”. GSK anticipates regulatory submissions in the “second half of 2022”.  

The race begins 

Dr Tony Wood, GSK’s Chief Scientific Officer, described these results as “truly exceptional”. 

“We believe that with the high vaccine efficacy demonstrated in this pivotal trial, our vaccine candidate has the potential to help reduce the significant global burden of RSV-associated disease in older adults”.  

The race is now on between GSK and Pfizer, with companies like Johnson & Johnson and Bavarian Nordic following closely behind. Citeline, a pharmaceutical intelligence company, suggests that the market for older adult RSV vaccination could grow to $5.2 billion by 2030. However, experts are warning that the two studies are not directly comparable due to variations in design and participant profiles.  

To hear more from GSK and Pfizer at the World Vaccine Congress in Washington 2023 get your tickets here.