Waning mRNA-1273 Vaccine Effectiveness against SARS-CoV-2 Infection in Qatar

In early 2021, Qatar launched a mass immunization campaign with the mRNA-1273 (Moderna)1 vaccine against coronavirus disease 2019 (Covid-19).2 We assessed the persistence of real-world vaccine effectiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and against Covid-19-related hospitalization and death.We used a test-negative, case-control study design to estimate vaccine effectiveness, applying the same methods used recently to assess waning effectiveness of the BNT162b2 (Pfizer-BioNTech) vaccine in the same population.3 Case participants (persons with a positive polymerase-chain-reaction [PCR] test for SARS-CoV-2) and controls (PCR-negative persons) were matched one to one according to sex, 10-year age group, nationality, reason for PCR testing, and calendar week of PCR test. Effectiveness was estimated against documented infection (a PCR-positive swab, regardless of the presence of symptoms) and against any severe Covid-19 cases (acute-care hospitalizations), critical Covid-19 cases (intensive care unit hospitalizations), or fatal Covid-19 cases (Covid-19-related deaths).