The Lancet Infectious DiseasesReal-world effectiveness of nirmatrelvir–ritonavir against BA.4 and BA.5 omicron SARS-CoV-2 variantsOver the past year of the COVID-19 pandemic, populations worldwide have been facing
the constant threat of the SARS-CoV-2 omicron variant and its sublineages, and the
high transmissibility and substantial immune evasion properties of the variants have
contributed to considerable numbers of hospitalisations and deaths. Nevertheless,
with the increasing availability and access to novel oral antiviral drugs (eg, nirmatrelvir–ritonavir
and molnupiravir) and hybrid immunity induced by infection and COVID-19 prime-boost
vaccines, the risk of progression to severe disease, hospitalisation, or death has
reduced.