Background: Monitoring vaccine effectiveness (VE) remains a priority for epidemiological research throughout the COVID-19 pandemic. VE against infection declines with the emergence of new SARS-CoV-2 variants of concern, but VE against the severe disease remains high. Therefore, we aimed to estimate the effectiveness of COVID-19 vaccines used in Russia against lung injury during delta and omicron surges.
Methods: We designed a case-control study (test-negative design) to estimate VE against any lung injury associated with COVID-19 between October 1, 2021 – April 28, 2022 (Delta variant dominance period followed by Omicron dominance period). We included the data of patients with symptomatic confirmed SARS-CoV-2 infection referred to the low-dose computer tomography triage centres.
Results: Among 23996 patients in the primary analysis, 13372 (55.7%) had any lung injury, and 338 (1.4%) had severe lung injury. The adjusted for age, sex and triage centre VE against any lung injury was 56% (95% confidence interval 54 to 59) for two-dose Gam-COVID-Vac (Sputnik V), 71% (68 to 74) for three-dose Gam-COVID-Vac (booster), 2% (-27 to 24) for EpiVacCorona, and 46% (37 to 53) for CoviVac. VE against severe lung injury was higher for all vaccines in our study.
Conclusions: Gam-COVID-Vac remains effective against lung injury associated with COVID-19, and one Gam-COVID-Vac booster can be seen as an appropriate option after a two-dose regimen. EpiVacCorona use in population-based vaccination should be halted until additional effectiveness and efficacy evidence is provided. CoviVac efficacy and safety data are still required to justify its use in a population-based vaccination despite our study results.
Trial registration: The joint study of COVID-19 vaccine effectiveness in St. Petersburg was registered at ClinicalTrials.gov (NCT04981405, date of registration — August 4, 2021)