A Study of the Effectiveness of Moderna COVID-19 Vaccine

This study utilized electronic healthcare data collected within the Kaiser Permanente Southern California (KPSC) integrated healthcare system which provides care to over 4.6 million individuals. Participants in this study received vaccination and were assessed for study outcomes as part of routine care. Vaccination information and study outcome status was assessed using procedure, diagnostic, and laboratory code information. Medical chart review was conducted to assess the association of severe outcomes (hospitalization and death) with COVID-19 illness. Analyses assessing absolute vaccine effectiveness will identify participants who receive Moderna COVID vaccine from the KPSC electronic healthcare database and match them to unvaccinated participants based on age, sex, race/ethnicity, and data of vaccination (index date). Vaccinated and unvaccinated participants will then be followed-up in the database for the occurrence of study outcomes. Cox proportional hazards regression will be used to compare the relative risk of study outcomes by vaccination status. Analyses of relative vaccine effectiveness will identify participants who receive specific dose number and formulation of Moderna COVID vaccine (Group N) from the KPSC electronic healthcare database and match them to a group of vaccinated participants with a different dose/formulation type (i.e. Group n-1). Similar matching criteria will be applied. Both groups will be followed for study outcomes and cox proportional hazards regression will be used to compare the relative risk of study outcomes by vaccination status.