COVID-19 vaccine effectiveness against severe disease from SARS-CoV-2 Omicron BA.1 and BA.2 subvariants – surveillance results from southern Sweden, December 2021 to March 2022
Jonas Björk, Carl Bonander, Mahnaz Moghaddassi, Magnus Rasmussen, Ulf Malmqvist, Malin Inghammar, Fredrik Kahn
Abstract
We compared vaccine effectiveness against severe COVID-19 between December 2021 and March 2022 when Omicron BA.1 and BA.2 were the dominating SARS-CoV-2 variants in Scania county, Sweden. Effectiveness remained above 80% after the transition from BA.1 to BA.2 among people with at least three vaccine doses but the point estimate decreased markedly to 54% among those with only two doses. Protection from prior infection was also lower after the transition to BA.2. Booster vaccination seems necessary to maintain sufficient protection.
Topics & Concepts
Coronavirus disease 2019 (COVID-19)Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)VaccinationMedicineVirology2019-20 coronavirus outbreakBooster (rocketry)Booster doseDiseaseInfectious disease (medical specialty)OutbreakVirusInternal medicineTiterPhysicsAstronomySARS-CoV-2 and COVID-19 ResearchVaccine Coverage and HesitancyCOVID-19 epidemiological studies