Through the miserable years of the COVID-19 pandemic, Dr. Bob Wachter, the University of California-San Francisco medical department chair, became a beacon of guidance to hundreds of thousands who followed his social media tips on avoiding the virus that killed more than 1.1 million Americans.

Though he works in a hospital that treated COVID patients, Wachter managed to avoid the respiratory disease through a regimen shared with his 274,000 Twitter followers of crowd avoidance, medical-grade mask-wearing, vaccination, boosting and a little luck as well.

But this week, he told them on Twitter, “my luck ran out.”

“My case is a cautionary tale, particularly for the ‘just a cold’ folks,” Wachter tweeted in a long thread about his ordeal Wednesday evening. “Mine definitely was not… I literally have scars to show for it.”

Few today pay much mind to the virus that upended life around the world from 2020 through 2022. But Wachter noted the virus is still out there and still poses a threat, though not as great as it did before less virulent virus variants and widespread population immunity from vaccines and prior infection led to declining deaths and an end to public health emergencies.

Wachter said he received his second “bivalent” vaccine booster tailored to protect against the more recent omicron variants of the virus in April, “so my protection against a severe case was still strong.” But he noted that the two-to-three month “window of protection” if offers “had passed.” He also acknowledged he “let down my guard a bit,” — he still wears an KN-95 mask on planes and in crowded rooms, but dines indoors without.

This week, Wachter said he was on clinical duty at UCSF hospitals where medical staff still are required to wear masks in patient areas.

He said he “felt fine until Sunday afternoon when, after leaving the hospital, I noticed a dry cough.”

“By Sunday night, I felt flu-ish, with a sore throat, fever, and chills,” Wachter tweeted. “Things got bad overnight. Monday, I woke up drenched in sweat, with a bad sore throat and a hacking cough.”

He took a home test for the COVID virus, which was negative, but he wasn’t convinced he didn’t have it and planned to take another. He called in sick to work, didn’t eat or drink, and “choked down 2 Tylenols.”

“Then I made a mistake — I took a shower,” Wachter wrote. “While the instinct to take a shower when you’re sweaty and gross is understandable, stepping into hot water when you’re dehydrated and flu-ish can cause your blood vessels to dilate, leading to a dangerous drop in blood pressure. And that’s what happened.”

Wachter wrote that he woke up “in a bloody pool on my bathroom floor.”

“There was a dent in the lid of a trashcan, likely where my head had hit,’ he wrote. “I remembered nothing. As I managed to get up, it was clear that my face was going to need stitches, and more than a couple.”

Wachter said he needed an overnight hospital stay, anti-seizure medication, stitches on his forehead and a neck collar for a small cervical fracture, and posted a photo of himself afterward, sporting a black eye as well.

“So my first case of COVID was pretty dramatic,” Wachter concluded. “If I hadn’t passed out, it would have been 3-4 days of a pretty nasty upper respiratory illness. But I did, and so my (unusual) case goes on my list of reasons that COVID continues to be worth avoiding if you can.”

Wachter said he has no idea where he contracted the virus — he hasn’t had any COVID patients lately — “so it’s likely to remain a mystery.” And although he has “joined the 3/4 of Americans who aren’t NoVids,” he said ” I don’t think it’ll change my behavior.” As long as the case rates remain low as they are now, he said he’ll “continue being relatively careful, but no more than I’ve been.”

But he added that “I will, however, be more careful about showering or taking a hot bath or hot tub when dehydrated. That’s one important takeaway from this mess.”

Wachter said Thursday by email that “I’m healing (slowly).”

His post drew some jabs from critics of the cautious COVID-avoidance he and other health experts preached that inspired economically punishing lockdowns and freedom-infringing mask and vaccine mandates whose effectiveness came under question as the virus continued to spread.

“Do you think it was right for people to lose their jobs,” asked one responder, a business owner with a Twitter handle Rocky Mountain High, because “they wouldn’t take a vaccine that stopped” the virus “for only 2-3 months?”

But it also drew well-wishing from supporters including former White House COVID response coordinator Dr. Ashish Jha, who responded on Twitter that he was “glad to hear you are on the mend.”

“The truth is,” Jha continued, “respiratory illnesses can wreak havoc in people’s lives — something we see all the time in the hospital. And why we should continue to take it seriously.”