That left the scientific community wondering where, exactly, Omicron came from. Some research suggests that this variant may have evolved in the body of someone who was immunocompromised; other molecular clues suggest that the virus jumped from a human to an animal where it evolved before jumping back into a human host.

It’s normal for a virus to mutate as it spreads from person to person, inevitably producing errors in its genetic code as it multiples. While most mutations may be benign, if any give the virus a survival advantage by making it, say, more transmissible or by aiding its ability to escape the host’s immune system, it may persist and result in new variants with more worrying traits.

“I don’t think