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MHRA Authorises First RSV Vaccine, Arexvy, for Adults

The Medicines and Healthcare products Regulatory Agency (MHRA) has for the first time approved a respiratory syncytial virus (RSV) vaccine, Arexvy, for adults over age 60. 

The authorisation was based on data in older adults from manufacturer GlaxoSmithKline's (GSK's) ongoing AReSVi-006 (Adult Respiratory Syncytial Virus) phase 3 vaccine efficacy trial. The results showed an efficacy rate of more than 80%.

GSK tested the vaccine against placebo in an observer-blind, multi-country trial involving 24,966 participants aged 60 and older from 17 countries. Participants were randomly assigned to a single dose of the vaccine or placebo. 

Efficacy of 82%, "Acceptable" Safety Profile

Initial results published in February showed that over a median follow-up of 6.7 months there were 7 cases (1.0 per 1000 participant-years) of RSV-related lower respiratory tract disease in the vaccine group compared with 40 cases (5.8 per 1000 participant-years) in the placebo group. 

The AReSVi-006 Study Group investigators said that this equated to a vaccine efficacy of 82.6% (96.95% confidence interval [CI], 57.9 - 94.1) against PCR-confirmed infection.

When infection was assessed on the basis of clinical signs or by the investigator, vaccine efficacy was 71.7% (95% CI, 56.2 - 82.3) against RSV-related acute respiratory infection and 94.1% (95% CI, 62.4 - 99.9) against severe RSV-related lower respiratory tract disease.

High vaccine efficacy was observed in various age groups and in participants with coexisting conditions and was similar against RSV A and B subtypes, the investigators said.

While the vaccine was more reactogenic than placebo, most adverse events were transient and of mild-to-moderate severity, including injection site pain, fatigue, myalgia, arthralgia, and headache. There was no increased incidence of serious adverse events or potential immune-mediated diseases in the vaccine group over the time of initial follow-up, which the investigators said was "an acceptable safety profile".

"No medicine would be approved unless it meets our expected standards of safety, quality, and effectiveness," Dr Laura Squire, chief healthcare, quality, and access officer at the MHRA, said.

Most Serious RSV Cases Associated With Comorbidities

RSV is a common, contagious respiratory virus that leads to an estimated 175,000 GP visits, 14,000 hospitalisations, and 8000 deaths each year in adults aged 60 years and over in the UK, the company said in a press release, noting that the majority of RSV hospitalisations were driven by those with underlying medical conditions, such as diabetes and chronic heart and lung disease.

The vaccine is already approved in the US and Europe. Further results from the trial are expected to be published later this year and will assess protection and immunogenicity over multiple seasons after a single-dose RSV vaccination in adults as well as an annual jab. Another trial enrolling adults aged 50 to 59, including participants with underlying comorbidities, has already been recruited.

GSK said that the RSV vaccine (recombinant, adjuvanted) contains recombinant glycoprotein F stabilised in the prefusion conformation (RSVPreF3). This antigen is combined with GSK's proprietary AS01E adjuvant system, which contains QS-21 STIMULON adjuvant licensed from Antigenics Inc, a wholly owned subsidiary of Agenus Inc.

"There is a substantial burden of RSV infection in older adults, which contributes to the seasonal winter pressures for the NHS," commented Prof Sir Andrew Pollard, director of the Oxford Vaccine Group, to the Science Media Centre. "Clinical trials of several products have shown that vaccination can boost immunity and reduce the risk of infection and hospitalisation with the potential to improve population health."

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