A three-year study has found robust evidence that one particular vaccine for respiratory syncytial virus (RSV) offers older adults long-term protection against the infection, even if efficacy wanes from season to season. Despite this, just a single dose cut serious illness by nearly two thirds, and getting a shot every year was not more beneficial.
The massive trial saw 24,972 people aged 60 or older get either the RSVPreF3 OA vaccine (brand name Arexvy, by GSK) or a placebo, administered in 275 clinics across 17 countries across five continents. After the first RSV season, it was 82.6% effective, 56% the following year and finally 48% after the third. While efficacy dipped, overall it halved milder RSV cases, and reduced serious infection needing medical attention by 70%.
These final results offer the clearest picture yet of how long the vaccine works and how safe it is over time.
RSV, a common virus that triggers lung infections, can be especially dangerous for older people and lead to bronchiolitis and pneumonia. According to the Centers for Disease Control and Protection (CDC), 100,000 to 150,000 US adults aged 60 and over are hospitalized due to the virus each year and an estimated 6,000 to 10,000 people in this demographic will die from it.
There has been a perceived rise in cases since the COVID-19 pandemic, however, this seems largely due to increased testing, particularly in children and in older and vulnerable populations. There are currently three vaccines available – this one from GSK, plus one each from Pfizer and Moderna. Both of those also had excellent initial Phase III results.
“Those at highest risk of severe complications of RSV infections include infants under six months old – especially premature infants – and those 60 and older,” said Dr Sandra Fryhofer, an Atlanta internal medicine physician and liaison for the American Medical Association. “RSV is especially dangerous for those with underlying medical conditions including heart or lung problems, as well as weakened immune systems.”
In 2022, the initial results from year one of the RSVPreF3 OA vaccine trial indicated it could be a game-changer for RSV protection.
"These are truly exceptional results given that today RSV remains one of the major infectious diseases without a vaccine, despite over 60 years of research," said Tony Wood, GSK Chief Scientific Officer in 2022 after the initial Phase III trial results were reported on. "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, including those at the greatest risk of severe outcomes due to their age or underlying comorbidities.”
Further research is needed to understand the optimal booster or revaccination regimen, as is investigating how mutations of the virus may impact vaccine efficacy.
The research was published in the journal The Lancet Respiratory Medicine.
Source: Deakin University via Scimex
