https://www.cdc.gov/mmwr/volumes/72/wr/mm7225a3.htm?s_cid=mm7225a3_w
During Delta, 2.7% of infections were reinfections. This jumped up to 10.3% during the initial BA.1 period and 28.8% for the BQ.1/BQ.1.1 period.
For hospitalizations, 1.9% were reinfections during Delta, 7.1% during BA.1, and 17.0% during BQ.1/BQ.1.1.
For deaths, 1.2%, 3.7%, and 12.3% respectively.
On one dimension this is just because so many people got their first infection during Omicron. But it is also because of increased immune evasion and waning immunity. Make sure you stay up to date on vaccination. Everyone is eligible for the Omicron bivalent vaccines, and those 65 and older or who are immunocompromised are eligible for a second bivalent.