Data Definitions for COVID-19 Vaccinations in the United States
CDC reports COVID-19 vaccination data online on COVID Data Tracker and in vaccination datasets. Sharing timely and accurate information with the public is one of CDC’s core activities. Timely and accurate reporting from jurisdictions provides the reliable data that can be reported by CDC. All reported numbers may change over time as updated data are continuously reported to CDC.
CDC estimates the number of people receiving at least one dose, the number of people who are fully vaccinated, and the number of people with booster doses. CDC estimates are based on data that include a dose number (first, second, boosters, or additional dose). To protect the privacy of vaccine recipients, CDC receives data without any personally identifiable information (deidentified data). Each jurisdiction or provider uses a unique person identifier to link records within their own systems. However, CDC cannot use the unique person identifier to identify individual people by name.
There are challenges in linking records when someone receives vaccine doses in different jurisdictions or from different providers. That person could receive different unique person identifiers for different doses. CDC may not be able to link multiple unique person identifiers for different jurisdictions or providers to a single person, and subsequent doses may appear to be a first dose when reported. Thus, CDC’s data may over-estimate first doses and under-estimate subsequent doses.
Another issue that poses challenges to estimating doses administered is that different jurisdictions and providers use different reporting practices. As people receiving doses are attributed to the jurisdiction in which they reside, the reporting method might change between doses if they move to a different jurisdiction. Also, CDC may lack information about a person’s residence. These issues can cause CDC’s dose number estimates to differ from those reported by jurisdictions and federal entities.
CDC has capped estimates of vaccination coverage shown on COVID Data Tracker at 95%. This cap helps address potential over-estimates of vaccination coverage due to first, second, and booster doses that were not linked. Other reasons for overestimates include census denominator data not including part-time residents or potential data reporting errors. Previously, CDC had capped estimates of vaccination coverage at 99.9%. CDC changed the cap to 95% on December 9, 2021, to account for differences in the accuracy of vaccination coverage estimates between different jurisdictions.
CDC encourages people to bring their CDC COVID-19 Vaccination record card with them to their appointment for another COVID-19 vaccine dose because having the card will help ensure the doses are linked.
CDC determines the number of people receiving at least one dose, the number of people who are fully vaccinated, and the number of people with booster doses based on information reported to CDC on dose number, dose manufacturer, administration date, recipient ID, and date of submission. Because the method used to determine dose numbers needs to be applied across multiple jurisdictions with different reporting practices, CDC’s dose number estimates might differ from those reported by jurisdictions and federal entities. People receiving doses are attributed to the jurisdiction in which they reside. This includes doses administered by Federal Emergency Management Agency (FEMA) partner sites, Health Resources and Services Administration (HRSA) partner sites, and federal entity facilities. In some limited circumstances, people might receive vaccinations outside the jurisdiction (state, territory, tribe, or local entity) where they live. When the vaccine manufacturer is not reported, the recipient is considered fully vaccinated with two doses.
COVID-19 Vaccinations Data Definitions
Total Doses Distributed
The total number of vaccine doses that have been distributed to vaccine provider locations.
For states, Washington DC, the U.S. Virgin Islands, and Puerto Rico, total counts of COVID-19 vaccine doses include doses distributed since December 14, 2020.
For the Republic of Palau, the Federated States of Micronesia, the Republic of the Marshall Islands, Guam, American Samoa, and the Commonwealth of the Northern Marianas Islands, total counts of COVID-19 vaccine doses include doses marked as shipped since December 13, 2020.
Total Doses Administered
The total number of vaccine doses that have been given to people in the United States since December 14, 2020. This is the date when the first dose was administered to a person in the United States under the Emergency Use Authorization not within a clinical trial.
People Receiving at Least One Dose
Represents the total number of people who received at least one dose of COVID-19 vaccine approved or authorized for use in the United States. This metric includes everyone who has received only one dose and those who received more than one dose.
People Who Are Fully Vaccinated
Represents the total number of people who have received the second dose in a two-dose COVID-19 vaccine primary series or one dose of a single-dose COVID-19 vaccine primary series approved or authorized for use in the United States.
- The number of people fully vaccinated with Johnson & Johnson’s Janssen (J&J/Janssen) vaccine does not equal the total number of J&J/Janssen vaccine doses administered because some people were reported to have received one or more mRNA vaccines (i.e., Pfizer-BioNTech, Moderna) prior to receiving the single-dose J&J/ Janssen vaccine.
- For reporting on CDC COVID Data Tracker, CDC counts people as being “fully vaccinated” if they received one dose of a single-dose vaccine or two doses on different days (regardless of time interval) of either an mRNA or a protein-based series.
People Who Are Eligible to Receive a First Booster Dose
Represents the total number of fully vaccinated people who are eligible to receive a first booster dose of an mRNA COVID-19 vaccine if it has been at least 5 months since their completed Pfizer-BioNTech or Moderna primary series or at least 2 months since their completed J&J/Janssen single-dose vaccine. Completion of a primary series does not distinguish if the recipient is immunocompromised and received an additional dose. This measure excludes recipients who received an “Other” primary series vaccine type.
People Who Received a First Booster Dose
Represents the total number of fully vaccinated people who later received another dose of any COVID-19 vaccine on or after August 13, 2021. This measure does not consider how much time has passed since the recipient was vaccinated or whether the vaccine recipient is immunocompromised, has an underlying medical condition, or is at high-risk from occupational and institutional exposure to COVID-19. People who are fully vaccinated are those who received the second dose in a two-dose COVID-19 vaccine primary series or one dose of a single-dose COVID-19 vaccine primary series.
Learn more about CDC’s recommendations for a COVID-19 vaccine booster dose.
On September 30, 2021, this language was changed to reflect the recommendation for a booster dose. People who received an additional dose since August 13, 2021, are included in this count.
People Who Received a Second Booster Dose
Represents the total number of fully vaccinated people who received two subsequent doses of COVID-19 vaccine beginning August 13, 2021, which includes people who received two booster doses and moderately or severely immunocompromised people who received one additional dose and one booster dose. This measure does not consider eligibility based on age, whether the vaccine recipient is immunocompromised, or how much time has passed since first booster dose. People who are fully vaccinated are those who received the second dose in a two-dose COVID-19 vaccine primary series or one dose of a single-dose COVID-19 vaccine primary series.
Learn more about CDC’s recommendations for a COVID-19 vaccine booster dose.
Rates per 100,000
Represent the rate of total doses distributed, the rate of total doses administered, the rate of people receiving at least one dose, the rate of people who are fully vaccinated, and the rate of people receiving a booster dose per 100,000. The rate per 100,000 people is calculated for the total population and select demographic groups (such as people ages 65 years or older) using population data. This allows comparison between areas with different population sizes.
Percent of the Population
Represents the percent of people receiving at least one dose, the percent of people who are fully vaccinated, and the percent of fully vaccinated people who have received a first booster dose. The percent of people who have received at least one dose and the percent of people who are fully vaccinated are calculated for the total population and select demographic groups (such as people ages 65 years or older) using population data.
7-Day Moving Average
This metric is calculated by summing a vaccination metric (such as people receiving dose one) for the most recent 7 days and dividing by 7.
County of Residence
CDC determines county of residence by matching the county Federal Information Processing Standard State (FIPS) code to the state as submitted in the raw data provided to CDC.