Vaccine effectiveness against severe COVID-19 during the Omicron wave in Germany: Results from the COViK study

PurposeCOViK - a prospective hospital-based multicenter case-control study in Germany - aims to assess the effectiveness of COVID-19 vaccines against severe disease. Here, we report vaccine effectiveness (VE) against COVID-19-caused hospitalization and intensive care treatment during the Omicron wave.MethodsWe analyzed data from 276 cases with COVID-19 and 494 control patients recruited in 13 hospitals from 1 December 2021 to 5 September 2022. We calculated crude and confounder-adjusted VE estimates.Results21% of cases (57/276) were not vaccinated, compared to 5% of controls (26/494; p < 0.001). Confounder-adjusted VE against COVID-19-caused hospitalization was 55.4% (95% CI: 12-78%), 81.5% (95% CI: 68-90%) and 95.6% (95%CI: 88-99%) after two, three and four vaccine doses, respectively. VE against hospitalization due to COVID-19 remained stable up to one year after three vaccine doses.ConclusionThree vaccine doses remained highly effective in preventing severe disease and this protection was sustained; a fourth dose further increased protection.Ethical review and trial registrationThe study was approved by the Ethics Committee of the Charité Universitätsmedizin, Berlin (EA1/063/21) and was registered at “Deutsches Register Klinischer Studien” (DRKS00025004).Potential conflicts of interestS. G. received payment/honoraria from Astra Zeneca, Boehringer Ingelheim, Roche Pharma, Novartis and Berlin Chemie, this had no influence on this work; all other authors reported no conflicts of interest.