COVID-19 vaccine effectiveness against hospitalization turned negative over time, according to U.S. Centers for Disease Control and Prevention (CDC) data presented on June 15.
The effectiveness against hospitalization plummeted to negative 8 percent for people who received one of the old COVID-19 vaccines, according to data from a CDC-run hospital network.
A dose of one of the updated bivalent vaccines moved the protection above zero, to 29 percent, but the protection fell back to negative 8 percent beyond 89 days, the data show.
The protection estimates were for adults without a compromised immune system from Jan. 23 to May 24, when the XBB strain was dominant in the United States. The data came from people hospitalized at one of 25 hospitals across 20 states that are part of the Investigating Respiratory Viruses in the Acutely Ill network. Both cases and controls were hospitalized with COVID-like illness but the cases tested positive for COVID-19 and the controls tested negative for COVID-19….