COVID-19 Vaccination Coverage


Important change as of June 1

As of June 1, 2022, we will be using 2020 DPH provisional census estimates* to calculate vaccine coverage percentages for state- and county-level tables (except coverage by CT SVI priority zip code).  2020 estimates will replace the 2019 estimates that have been used. Caution should be taken when making comparisons of percentages calculated using the 2019 and 2020 census estimates since observed difference may result from the shift in the denominator.  The age groups in the state-level data tables will also be changing as a result of the switch to the new denominator.
*  DPH Provisional State and County Characteristics Estimates April 1, 2020. Hayes L, Abdellatif E, Jiang Y, Backus K (2022) Connecticut DPH Provisional April 1, 2020 State Population Estimates by 18 age groups, sex, and 6 combined race and ethnicity groups. Connecticut Department of Public Health, Health Statistics & Surveillance, SAR, Hartford, CT.

This page summarizes available information on COVID-19 vaccination in CT. COVID-19 vaccination data tables can be found here including information on how the data are analyzed. Other data on COVID-19 in CT are posted here
COVID-19 vaccination data are updated weekly on Thursdays. Weekly reports include doses reported to CT Wiz by 11:59 P.M. the Tuesday prior to publication. All COVID-19 vaccine data are preliminary and are subject to change as additional records are received and as duplicate records are removed, and other errors are corrected.  
Currently, the Pfizer vaccine is approved for use in people 16 years and older and authorized for people 5 to 15. The Moderna vaccine is approved for people 18 and over. The Johnson & Johnson vaccines is authorized for people 18 years and over. Generally, people are considered to have completed a primary series if they have received 2 Pfizer or Moderna vaccine doses or 1 Johnson & Johnson vaccine dose. However, people who are moderately or severely immunocompromised are recommended to receive one additional dose in the primary series. All people 12 and over are currently recommended to receive a booster dose after completion of the primary series. At this time, some people may receive a second booster (people 50 years and over, moderately or severely immunocompromised people, people who have received only J & J vaccine). CDC recommendations on COVID-19 vaccination can be seen here. 
In the data shown here, a person who has received at least one dose of COVID-19 vaccine is considered to have initiated vaccination. A person is considered fully vaccinated if he/she has completed a primary vaccination series by receiving 2 doses of the Pfizer or Moderna vaccines or 1 dose of the Johnson & Johnson vaccine. The fully vaccinated are a subset of the people who have received at least one dose.
A person who completed a Pfizer, Moderna or Johnson & Johnson primary series (as defined above) and then had an additional dose of COVID-19 vaccine is considered to have had additional dose 1. The additional dose may be Pfizer, Moderna or Johnson & Johnson and may be a different type from the primary series. For most people, additional dose 1 is a booster. However, additional dose 1 may represent a supplement to the primary series for a people who is moderately or severely immunosuppressed.
Unless otherwise specified, coverage percentages posted through 5/26/2022 are based on 2019 CT population estimates. As of 6/1/2022 provisional 2020 estimates will be used. 
More information on the CT DPH Immunization Program, including on the Connecticut Immunization Information System (CT WIZ), can be found here. Information on where to find a COVID-19 vaccination click here.

The total number of first doses of COVID-19 vaccine given since it became available in December 2020 is shown here by week.
The number and percentage of people who have had at least one dose of COVID-19 vaccination, are fully vaccinated, and have had additional dose 1 by age group is shown below.  The age groupings change as of 6/1/2020, to accommodate the switch to the DPH provisional 2020 census estimates.  
Vaccine coverage (at least one dose) by race/ethnicity and age group is shown below. Data on coverage by race/ethnicity should be interpreted with caution because of the challenges of classifying race/ethnicity and because people with a missing or other race cannot be included in the vaccine coverage percentages.  Click here to see data on those who are fully vaccinated and who have received additional dose 1 and for a more in-depth description of the methods used to assess vaccine coverage by race/ethnicity and their limitations. Age grouping change as of 6/1/2020, to accommodate the switch to the DPH provisional 2020 census estimates.  
Vaccine coverage is also assessed based on where people live including by county, town and census tract.  Town of residence is verified by geocoding the reported address and then mapping it to a town using municipal boundaries. If an address cannot be geocoded, the reported town is used, if available. A census tract cannot be determined for addresses that cannot be geocoded. 
The map below shows the percentage of people who have had at least one dose of COVID-19 vaccine by town of residence. Town-level coverage estimates have been capped at 100%. Observed coverage may be greater than 100% for multiple reasons, including census denominator data not including all individuals that currently reside in the town (e.g., part-time residents, change in population size since the census), errors in address data or duplicate or mismatched.
Additional town-level data including percentage who are fully vaccinated or who have received additional dose 1 can be found here (all ages) and here (by age group). Town-level population by age is based on the 2014 CT annual estimates for the age group maps. 
Caution should be used when interpreting coverage estimates for towns with large college/university populations since coverage may be underestimated. In the census, college/university students who live on or just off campus would be counted in the college/university town. However, if a student was vaccinated while studying remotely in their hometown, the student may be counted as a vaccine recipient in that town.   
Coverage by census tract is shown in the map below.  A census tract cannot be determined for addresses that cannot be geocoded. Again, coverage is capped at 100%. Census tract population is based on the 2019 5-year American Community Survey. 
Additional census- and town-level data can be found here and here. Town-level population by age is based on the 2014 CT annual estimates for the age group maps.  Census tract population is based on the 2019 5-year American Community Survey.   
The Centers for Disease Control and Prevention has developed a Social Vulnerability Index (SVI) to help officials identify communities that may need support during an event like a pandemic. The CDC SVI ranks census tracts on 15 social factors, including poverty, lack of vehicle access, minority status and crowded housing. The higher the SVI score the greater the vulnerability of a community. CT DPH has applied the SVI method to zip codes and designated zip codes in the top 20% as SVI Priority Zip Codes.  Vaccine coverage is compared for people who live in a priority zip code with that of those who live in another zip code.  Coverage estimates by SVI Priority Zip Codes are based on 2018 census data provided by ESRI. 

Data Quality and Status

Connecticut COVID-19 Vaccine Program providers are required to report information on all COVID-19 vaccine doses administered to CT WiZ, the Connecticut Immunization Information System. This includes doses given to residents of CT and to residents of other states vaccinated in CT. Data on doses administered to CT residents out-of-state are being added to CT WiZ jurisdiction-by-jurisdiction. Doses administered by some Federal entities (including Department of Defense, Department of Correction, Department of Veteran’s Affairs, Indian Health Service) are not yet reported to CT WiZ.  Data reported here reflect the vaccination records currently reported to CT WiZ. However, once CT residents who have received doses in each jurisdiction are added to CT WiZ, the records for residents of that jurisdiction vaccinated in CT are removed. For example, when CT residents vaccinated in NYC were added, NYC residents vaccinated in CT were removed.
CT DPH and its partners go to great lengths to provide high quality data that is free of errors. Because of the nature of public health surveillance, there are times when data updates are necessary for a number of reasons. These include, but are not limited to, errors contained in the data CT DPH receives, updates to existing data as additional or new information becomes available, and the on-going de-duplication of vaccination data. CT DPH and it's local, state, and federal partners are all working to ensure only the best data and information are available for state and local decision makers.