Pink eye, or conjunctivitis, is a known symptom of COVID-19, but it is relatively rare — and many other viruses or bacteria can cause this very common condition. As of now, it’s unclear what caused the redness in Pence’s eye. BuzzFeed News contacted the vice president’s office and the Trump campaign for comment but did not immediately receive a response.

Daniel Volland, a Seattle optometrist, said he didn’t believe the eye was infected, speculating Pence had a broken blood vessel.

Still, celebrities and other people with prominent accounts on Twitter claimed without evidence that he has pink eye and, potentially, COVID.