Persistent attenuation of lymphocyte subsets after mass SARS-CoV-2 infection.

Summary: When people get sick with COVID-19, their immune system fights back. But does the immune system fully recover afterward? Researchers looked at blood tests from over 40,000 people before, during, and after a huge wave of COVID-19 infections. They found that certain white blood cells, which protect us from illness, stayed lower than normal for a long time. This drop was especially bad for people who already had heart problems. This means COVID-19 can cause long-lasting damage to our immune system, which helps explain why some people get "long COVID." Doctors may need to give special care to keep these patients healthy.