Important update: Healthcare facilities
CDC has updated select ways to operate healthcare systems effectively in response to COVID-19 vaccination. Learn more
UPDATE
Given new evidence on the B.1.617.2 (Delta) variant, CDC has updated the guidance for fully vaccinated people. CDC recommends universal indoor masking for all teachers, staff, students, and visitors to K-12 schools, regardless of vaccination status. Children should return to full-time in-person learning in the fall with layered prevention strategies in place.
UPDATE
The White House announced that vaccines will be required for international travelers coming into the United States, with an effective date of November 8, 2021. For purposes of entry into the United States, vaccines accepted will include FDA approved or authorized and WHO Emergency Use Listing vaccines. More information is available here.
UPDATE
Travel requirements to enter the United States are changing, starting November 8, 2021. More information is available here.

Monitoring COVID-19 Cases, Hospitalizations, and Deaths by Vaccination Status

Monitoring COVID-19 Cases, Hospitalizations, and Deaths by Vaccination Status
Updated Mar. 21, 2023
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COVID-19 Infection after Vaccination

COVID-19 vaccines help protect against severe illness, hospitalization, and death. People who are up to date on COVID-19 vaccines are much less likely to experience severe symptoms than people who are not up to date, if they get infected with SARS-CoV-2, the virus that causes COVID-19.

People who get infected after vaccination can spread COVID-19 to other people. When more virus is circulating, more infections will occur even where vaccination rates are high. If you live in a county with a high COVID-19 Community Level, you and others in your community, whether vaccinated or not, should take more steps to protect yourself and others, such as increasing indoor ventilation or wearing a mask in indoor public places.

Monitoring COVID-19 Rates by Vaccination Status

CDC uses public health surveillance data reported by participating health departments, hospitals, and long-term care facilities to monitor rates of COVID-19 cases, hospitalizations, and deaths by vaccination status.

Monitoring rates of COVID-19 cases, hospitalizations, and deaths by vaccination status over time, as well as by age, can help identify overall patterns or trends.

CDC analyzes surveillance data by vaccination status to

  • Better understand patterns of COVID-19 among people who are vaccinated and unvaccinated.
  • Identify signals of potential changes in vaccine effectiveness, which can be confirmed through more robust, controlled vaccine effectiveness studies.

CDC uses the following platforms and methods to collect and analyze surveillance data on COVID-19 cases, hospitalizations, and deaths by vaccination status:

Case surveillance

CDC collaborates with many state and local health departments that regularly link case surveillance, immunization registry, and vital registration data to monitor rates of COVID-19 cases and deaths by vaccination status, including receipt of booster doses. These rates are published monthly on COVID Data Tracker.

Data from the participating health departments represent a large proportion of the U.S. population and all regions of the country. The volume of this data allows CDC to analyze important outcomes, like COVID-19-associated deaths. However, while these analyses may provide signals of potential changes in vaccine effectiveness, they cannot account for some factors that could impact the results – for example, underlying medical conditions or prior infection.

Analyses of these case surveillance data by vaccination status were published in CDC’s MMWR for periods of the Delta variant and Omicron variant.

COVID-NET

CDC monitors rates of COVID-19 hospitalizations by vaccination status using COVID-NET. COVID-NET is a population-based, sentinel surveillance system that collects reports of laboratory-confirmed COVID-19-associated hospitalizations. COVID-NET covers approximately 10% of the U.S. population.

CDC publishes monthly rates of laboratory-confirmed COVID-19 hospitalizations by vaccination status on COVID Data Tracker. The data is updated monthly.

National Healthcare Safety Network

Infections in long-term care facility residents by vaccination status are reported through a network of approximately 15,000 medical facilities called the National Healthcare Safety Network (NHSN). Analyses of these long-term care facility data were published in CDC’s MMWR:

In addition, NHSN is used to monitor weekly infections by vaccination in dialysis patients among approximately 8,000 dialysis facilities.

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