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May 27, 2022 - COVID-19: Rates of Illness After Vaccination

The COVID-19 vaccines are extremely effective at preventing serious illness, hospitalization, and death. Fully vaccinated people who test positive for COVID-19 more than 2 weeks after their completed vaccine dose series are called "breakthrough infections." No vaccine is 100 percent effective, and as such we expect to see some fully vaccinated people test positive for COVID-19, but breakthrough cases typically report mild illness or no symptoms.

Your likelihood of being infected with the virus that causes COVID-19 is determined by many factors, which include vaccinations, but also include the level of transmission and vaccine coverage in your community, whether you or others wear masks as recommended, the number of people you have close contact with, and more. On average, fully vaccinated individuals are less likely to be infected, hospitalized, and die from COVID-19 compared to unvaccinated individuals.

The Wisconsin Department of Health Services (DHS) and The Centers for Disease Control and Prevention (CDC) monitor rates of COVID-19 cases and deaths by vaccination status. The graph below illustrates the rates of COVID-19 cases among fully vaccinated people with and without an additional or booster dose and compare them to rates among unvaccinated people.

The Wisconsin Department of Health Services (DHS) will be updating this data monthly. Visit COVID-19: Illness After Vaccination | Wisconsin Department of Health Services or CDC COVID Data Tracker: Rates of COVID-19 Cases and Deaths by Vaccination Status for more information.