(Reuters) -Europe's medicine regulators on Tuesday backed the World Health Organization's recommendation to update the antigen composition of COVID-19 vaccines to target one of the currently dominant XBB variants ahead of the upcoming autumn vaccination campaign.
Advisory groups related to the WHO suggested that, while waiting for more data, the monovalent XBB-containing vaccines could be considered a reasonable choice and individuals at risk of progression to severe disease such as older adults should be given priority, according to European Centre for Disease Prevention and Control (ECDC) and European Medicines Agency (EMA).
Marco Cavaleri, EMA's head of health threats and vaccines strategy, explained the thinking behind the choice of monovalent vaccines at a briefing on Tuesday.
"What we learned is that individuals that have been repeatedly vaccinated with the ancestral strain... already have good immunity against all the viruses that have been circulating in the past. But this immunity is not very good for what looks like is coming up next," he said.
For that reason, he said, the EMA and ECDC felt that it was important for adapted vaccines to trigger an immunity that is more directed against these new sub-variants that are dominant at the moment, like the XBB family, "to increase the chances of having good protection not only from severe disease but also from infection and the mild symptomatic disease."
Novavax Inc's R&D chief Filip Dubovsky said on Monday that "a monovalent vaccine appears to be the way to go."
The company is producing an updated COVID vaccine that is likely to be protective against other fast-growing coronavirus variants circulating in the United States.
Once authorised, these monovalent XBB-adapted vaccines could also be used for primary vaccination of young children below 5 years of age who are at risk of complications or severe disease, the EMA statement said.
The WHO in May said that new formulations should aim to produce antibody responses to the XBB.1.5 or XBB.1.16 variants, adding that other formulations or platforms that achieve neutralizing antibody responses against XBB lineages could also be considered.