The FDA updated the drug information on AstraZeneca's Evusheld, the only COVID-19 preexposure prophylaxis treatment with emergency use authorization, on Oct. 3 with the warning that it may lose efficacy as the virus evolves.
Evusheld, which is tixagevimab and cilgavimab, has proven effective against omicron's early variants and subvariants, but in late June, the FDA recommended repeated dosing every six months as subvariant BA.5 quickly dominated cases.
Now, "there is a potential risk of treatment failure due to the development of viral variants that are resistant to tixagevimab and cilgavimab," according to the FDA.
The regulator said it still recommends the treatment but adds that physicians "should consider the prevalence of SARS-CoV-2 variants in their area [...] when considering prophylactic treatment options."