If you're fully vaccinated against COVID-19, just how much should you fret a possible breakthrough infection?
"I think (you can) be concerned and not worried, if that's a meaningful distinction," Dr. Bob Wachter, the chair of UCSF's Department of Medicine, told KCBS Radio’s Doug Sovren on Monday during "The State of California."
Dr. Wachter pointed to a handful of factors in explaining the difference.
For one, none of the vaccines are 100% protective against subsequent infections. Thanks to the delta variant's higher rate of transmissibility, infections among all people – regardless of their vaccination status – have increased substantially.
From May 26 until Monday, California's seven-day rate of cases per 100,000 residents increased from 2.3 to 11.2. In San Francisco, the rate increased from 1.4 to 13.9, according to the latest state data.
The risk of being hospitalized or dying of COVID-19 after full vaccination is close to zero, but it exists. Plus, he said recent research indicates that the vaccines' effectiveness starts to wane ever so slightly after six months.
As a result, Dr. Wachter urged caution amid rapidly rising cases throughout the state.
"I'm not worried, but I'm a little bit more careful than I would've been a few months ago," he said.
Dr. Wachter said he anticipates an announcement about requiring booster shots "fairly soon," because of the six-month data and the continued spread of the delta variant. The rollout should look similar to the initial vaccine push, he said, with people vaccinated more than six months ago likely to receive their booster shots first.
Immunocompromised people would be prioritized, as would older people and, perhaps, those who received the Johnson & Johnson single-shot vaccine. You might not receive a booster shot before the end of the year if you were fully vaccinated within the last three months, but Dr. Wachter said an additional shot is going to be a reality.
"That seems almost inevitable," he said.
