Table 1: COVID-19 Breakthrough Event Data, Source, and Notes by State

NOTE: *Where states did not specify the start of their collection periods of COVID-19 breakthrough event data, we assumed a start date of January 1, 2021. **In some cases, it is not possible to determine whether a hospitalization or death of a vaccinated individual with COVID-19 was due to COVID-19. States that are greyed out either do not provide COVID-19 breakthrough data or have not collected data for longer than one month, such as in the case of SC. "N/A" refers to data that is either not applicable (for states not reporting breakthrough data) or missing data. Many states only include data on state residents. For some states, breakthrough data after May 1, 2021 only includes data on breakthrough hospitalizations and deaths. For AR, data obtained through personal communication with state officials. Hospitalization data not available for the full observation period of AR's data, thus, the previous week's hospitalization totals were used to estimate the last week of missing data.