Boosters are not officially recommended at this time. The vaccines continue to be effective against hospitalization and death. There are some groups of people who have a weaker immune response to the vaccine: older patients, people on certain immunosuppressing drugs and people who have had solid organ transplants. The CDC is likely to recommend booster doses in some of those groups before the end of 2021 after reviewing all the data. Hospitals are reporting on breakthrough cases so that the efficacy of the vaccine can be tracked. If and when the vaccine efficacy falls below a certain level, the recommendation for booster doses will be amended.