While UCSF Department of Medicine Chair Dr. Bob Wachter has mostly been a sunny and optimistic voice through the pandemic, he sounds a bit shaken by a case of Omicron that hit close to home: his 28-year-old son.

Over the last two years, Dr. Wachter has been the king of long Twitter threads in which he tries to spell out, in layman's terms, the important details in the emerging data about the pandemic. At some points this has been a thankless and chaotic task, with the pandemic picture shifting rapidly and the data not always reliable or clear. But when the pandemic came for one of his loved ones last week, he found that his analytical, clinician self gave way to a different one, a worried dad who didn't like to think about any odds of his son having a severe illness at all — even though he knew, rationally, that the odds of relatively mild illness were very high.

Wachter tweeted about the ordeal on Sunday, he said, with his son's permission, and the story was subsequently picked up by the Chronicle. "I’ve been tweeting about Covid for nearly 2 years," Wachter wrote. "But this week it became personal when my 28-year-old younger son got it."

Wachter's son likely became infected Monday, he said, after spending time with a friend watching a movie at home — a relatively low-risk activity — but the friend later tested positive for COVID. His son began feeling symptoms Wednesday, which included a bad sore throat, chills, aches, etc.

They then went through the experience that many San Franciscans are having right now — the soonest available PCR test appointment was four days away, so not very useful, and rapid tests are nearly impossible to find. Wachter had one stashed away at home, and the first one his son took was negative — but the symptoms told a different story. They ended up doing a second at-home test, swabbing throat and tonsils as well as nose, and it was positive. His son prepared himself for five days of strict isolation.

He explains that his son, while young and therefore not at very high risk, is overweight and therefore at "moderately high risk" for a severe case. But since he is vaccinated and boosted with three total Moderna shots, Wachter found himself doing the math as he often does in his threads.  He figures, with all these factors, his son likely had a one-in-300 chance of needing hospitalization. He would later calculate that, with treatment from a hard-to-obtain anti-viral pill, like Merck's or Pfizer's, they might get that chance down go one in 500 — but his son's physician ended up advising against it.

It's a moving story in large part because Wachter has been such a calm, rational, and optimistic voice in all this. And even he found himself having relatively irrational worries, like that his son might go to bed and not wake up the first night after he was showing symptoms. He admits, despite all of his knowledge, when it's your kid, "you freak out a bit."

He goes through his worries about long COVID — which many of us know all too well — and he admits that the jury is still out on the risks, data-wise. "The literature is a mess: some studies show 50% of people have persistent (>1 month) symptoms. Other studies say it's more like 5%. It seems like vax lowers the risk. So it’s a concern, but there’s not much we can do but wait & see."

Also, he continues to tout the effectiveness of the vaccines — even though all this Omicron business has frustrated our belief that boosters, etc. should keep most of us from getting sick at all.

And, he concludes, four days into the symptomatic infection, "My son should do OK, but the illness & the anxiety [COVID] causes are miserable. Resigning ourselves to getting Omicron doesn’t seem right, especially since the surge may be short-lived. I still think it’s an experience best avoided – for you and your loved ones – if you can."

Wachter posted an update Sunday thanking everyone for the concern and their offers of test kits, and saying his son is "Better today, though throat's still bad. Many going through far worse."

Wachter already advised us not to attend big New Year's Eve parties, and just before the new year he surmised that the Bay Area should be in pretty good shape once this surge abates, probably in February, when COVID is more or less "like the flu" in terms of its seasonality and overall impacts.

That may not be the case for all parts of the country, where large pockets of unvaccinated people remain, or for other parts of the world. And once again the experts are not all in agreement.

Bette Korber of Los Alamos National Laboratory, who has been tracking the evolution of the COVID-19 virus, tells Bay Area News Group that, sure, the virus may slowly morph into something like the common cold, and far fewer of us will get severely sick from it.

"But it is very hard to define what ‘slow’ means, and to predict its evolutionary trajectory, even over the next year or so,” Korber says. “It may be a bumpy ride.”

Related: Top UCSF Doc Says That We Could Be in ‘A Pretty Good Situation in February’ Where COVID Is ‘Like the Flu’