Figure 1. Proportion of Adults in the COVID-19–Associated Hospitalization Surveillance Network (COVID-NET) Catchment Area and Adults 18 Years or Older With COVID-19–Associated Hospitalizations Admitted January 1, 2021, to April 30, 2022, Vaccinated With a Primary Series, With and Without a Booster Dose,^a by Age Group and Month of Admission, COVID-NET, 13 States^b.

^aBecause the immune status of all cases was not known, an additional dose (recommended for persons with a weakened immune system) cannot be distinguished from a booster dose. This is a relevant consideration because vaccines can be less effective in persons with a weakened immune system. Additional doses described as booster doses in the figure became available to the general public on August 13th.

^bCalifornia, Colorado, Connecticut, Georgia, Maryland (data excluded beginning December 4, 2021), Michigan, Minnesota, New Mexico, New York, Ohio, Oregon, Tennessee, and Utah.