Clinical severity of, and effectiveness of mRNA vaccines against, covid-19 from omicron, delta, and alpha SARS-CoV-2 variants in the United States: prospective observational study.
Adam S LauringMark W TenfordeJames D ChappellManjusha GaglaniAdit A GindeTresa McNealShekhar GhamandeDavid J DouinH Keipp TalbotJonathan D CaseyNicholas M MohrAnne ZepeskiNathan I ShapiroKevin W GibbsD Clark FilesDavid N HagerArber ShehuMatthew E PrekkerHeidi L EricksonMatthew C ExlineMichelle N GongAmira MohamedNicholas J JohnsonVasisht SrinivasanJay S SteingrubIthan D PeltanSamuel M BrownEmily T MartinArnold S MontoAkram KhanCatherine L HoughLaurence W BusseCaitlin C Ten LohuisAbhijit DuggalJennifer G WilsonAlexandra June GordonNida QadirSteven Y ChangChristopher MallowCarolina RivasHilary M BabcockJennie H KwonNatasha HalasaCarlos G GrijalvaTodd W RiceWilliam B StubblefieldAdrienne BaughmanKelsey N WomackJillian P RhoadsChristopher J LindsellKimberly W HartYuwei ZhuKatherine AdamsStephanie J SchragSamantha M OlsonMiwako KobayashiJennifer R VeraniManish M PatelWesley H Selfnull nullPublished in: BMJ (Clinical research ed.) (2022)
mRNA vaccines were found to be highly effective in preventing covid-19 associated hospital admissions related to the alpha, delta, and omicron variants, but three vaccine doses were required to achieve protection against omicron similar to the protection that two doses provided against the delta and alpha variants. Among adults admitted to hospital with covid-19, the omicron variant was associated with less severe disease than the delta variant but still resulted in substantial morbidity and mortality. Vaccinated patients admitted to hospital with covid-19 had significantly lower disease severity than unvaccinated patients for all the variants.