cientists estimate that over 20% of people who get infected with COVID never have any symptoms – and a portion of them never even know they were infected. Now a new study published in Nature on July 19 says their genetics might be why the virus didn't make them sick.

Some people have a version of a gene in their immune system called HLA-B that protects them from feeling the effects of the virus. The study found that people with this special HLA-B variant are 2 to 8 1/2 times more likely to be asymptomatic than those without the variant.