I might have had COVID. When should I get my next booster?

Dear Advice Team: I’m trying to figure out the timing of my next booster. My girlfriend got COVID a few weeks ago (very mild case), and seeing as we live together in a small San Francisco apartment with no real way to isolate, I assumed I’d get it too. I did get some symptoms — scratchy throat, cough, congestion, headache — but never actually tested positive. I assume I got a very mild case and my system fought it off. But was that enough of an infection to wait two to three months for a booster, to maximize it? Or should I get a booster sooner rather than later, because I never tested positive?

Dear Reader: It sounds like you are not alone in this gray area, and I imagine it’s confusing for you and others in this situation to figure out what to do next.

The U.S. Centers for Disease Control and Prevention recommends that anyone 12 and older get the new omicron-targeting booster at least two months after their last COVID shot or three months after recovering from a COVID infection. Some studies and experts suggest that people wait longer to get the biggest benefit from an additional booster.

It sounds like your girlfriend’s infection occurred sometime toward the end of August, which under the CDC’s three-month recommendation would put her booster around the end of November.

But your difficulty is that you don’t have solid proof — a positive test — indicating you were actually infected. If you didn’t have

COVID, the recommendations indicate that you should get the new booster sooner — two months after your last shot (though you did not indicate when that was).

First, based on what you described, the infectious disease experts I spoke to seemed to agree there is a good chance you were indeed infected with COVID, even though you tested negative.

UCSF infectious disease expert Dr. Peter Chin-Hong said he would assume you had COVID because your girlfriend had a confirmed case, and you had “compatible symptoms.”

“COVID is notorious for rapid test false negatives in the age of omicron, particularly early in the course of symptoms,” he said. “Depending on how many tests were done and whether a PCR was eventually obtained, it was likely a false negative test.”

You didn’t indicate whether negative rapid tests were confirmed with a negative PCR test — if that was the case, then John Swartzberg, infectious disease doctor and professor emeritus at UC Berkeley School of Public Health, said he doesn’t think you had COVID. There are “many other respiratory viruses circulating” that could have caused your symptoms.

But if you used only rapid tests, then it’s likely you were infected, since you and your partner live together, she had a confirmed case and you also had symptoms, Swartzberg said.

Next, you ask whether your possible COVID infection means you should wait to get a booster dose, or get one sooner.

COVID cases have been declining in the Bay Area since the peak of around 60 cases per 100,000 people in June driven by the BA.4 and BA.5 omicron subvariants, the latter of which remains dominant. The region’s case rate was 13.4 per 100,000 as of Sept. 13, according to state and local data collected by The Chronicle. In San Francisco, where you live, the latest case rate is even lower at 5.6 cases per 100,000.

Given that we’re in a “COVID lull” right now, it isn’t urgent to get boosted unless you haven’t had a recent infection or gotten a vaccine dose in 2022, according to Chin-Hong.

“As long as BA.4/BA.5 stay dominant, it is likely that the writer and girlfriend were both infected with BA.5, so that gives them easily a three-month window period of a BA.5 invisibility cloak,” he wrote in an email.

Getting a booster gives your body a temporary boost in antibodies, which decreases the chances of a breakthrough infection, said Nadia Roan, an immunologist and investigator at San Francisco’s Gladstone Institutes. But if you really did have a COVID infection, waiting to boost “should give the immune system more time to mature before hitting it again with another exposure to viral protein, which based on some studies would elicit a more robust response in the long run,” she said.

“Assuming the inquirer is not immunocompromised nor has other pre-existing factors associated with higher risk of severe COVID, I would suggest waiting,” Roan wrote in an email.

You can still get your booster in time for a possible winter uptick in cases, and be ready for any holiday gatherings and travel, Chin-Hong said. You might consider getting boosted earlier if you plan to be in a crowded indoor situation or travel to a place with high infection rates, Roan said. If a new variant arrives, Chin-Hong said, that would be time to reevaluate when to get boosted.

Swartzberg agreed that “we are at a relatively quiet time with the pandemic, so the urgency of a booster is somewhat less.” If a winter surge is coming, it likely will start just after Thanksgiving, he said.

Regarding you and your girlfriend, Swartzberg said, “Assuming they both had COVID, they essentially were boosted with their illness (it is true that a very mild case of COVID may not be immunizing in some people). They should wait at least three months after having COVID before getting the booster according to the CDC. I think this is reasonable.”

Beyond that, Swartzberg said, “timing the booster is fraught with problems,” and he would not suggest doing it. The two major variables, he said, are what the virus is going to do — such as the appearance of a new more transmissible or immuneevasive variant — and what we are doing, such as behaviors that put us at higher risk for infection.