“I don’t think we know anything about the virulence. What we’re worried more about is the transmissibility and the immune-evasion capabilities,” said Dr. Amesh Adalja, an infectious disease doctor who is a senior scholar at the Johns Hopkins Center for Health Security.

Adalja said he suspected that vaccination would still provide strong protection against severe disease, while unvaccinated people who have natural immunity from previous Covid infections could be at even higher risk for getting the virus again.

“It may be that breakthrough infections or reinfections become more common with this, but it’s probably unlikely that you see severe breakthrough infections become common in healthy people,” he said.