There’s pretty much no one left in the US who hasn’t been exposed to the coronavirus, whether by vaccination, infection or both.
Researchers can test blood samples taken for other reasons to see if patients have previously had COVID-19.
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Your blood can hold a record of past illnesses. That information can reveal how many people have had a certain infection – like 58% of Americans having had COVID-19 by the end of February 2022.
Even if you’re feeling fine, you might be infected by the SARS-CoV-2 virus that causes COVID-19.
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After your body fights off an infection, antibodies remain in your blood. Two researchers explain how tests identify these antibodies and what the data can be used for.