What is a Post-Vaccination COVID-19 Case?
Post-vaccination COVID-19 infections are infections occurring in persons who have completed their primary vaccine series (i.e., full one-dose or two-dose COVID-19 vaccination series) or persons who have completed their primary series and a booster. These infections are also referred to as breakthrough infections.
What is a Case Among Boosted Individuals?
Cases among boosted individuals are defined as those who have received a COVID-19 booster doses and have a positive SARS-CoV-2 molecular (e.g. PCR) test 14 days or more after their booster dose.
How are COVID-19 Cases Among Vaccinated and Boosted Individuals Identified?
The California Department of Public Health (CDPH) is identifying post-vaccination cases by analyzing the immunization and case registries to find individuals who have a positive SARS-CoV-2 molecular test (e.g. PCR) at least 14 days after they have completed their full vaccination series or 14 days after they have completed their booster. Local Health Jurisdictions (LHJs) are also encouraged to alert CDPH of post-vaccination cases especially if they result in severe disease (e.g., hospitalization or death) or if they are associated with an outbreak.
Why are we Tracking Cases Among Vaccinated and Boosted Individuals?
Tracking cases of COVID-19 that occur after vaccination and/or boosters is important for monitoring the impact of immunization on the occurrence of COVID-19 infections, hospitalizations, and deaths. While COVID-19 vaccines are safe and effective, some cases are still expected in persons who have been vaccinated or boosted, as no vaccine is 100% effective. If the number or severity of cases among vaccinated or boosted person exceeds expected levels, this could be a signal of reduced protection against a variant or waning protection over time. Whole genome sequencing of these cases, especially severe ones, can help characterize the effectiveness of current vaccines against variants.
What is the Current Data on Cases by Vaccination Status in California?
Rates of cases and deaths among vaccinated or boosted individuals compared with rates among people who are unvaccinated are updated weekly, and can be found on the COVID-19 Cases by Vaccination Cases Dashboard.
Originally Published on June 9, 2021