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Bivalent COVID booster appointments are now readily available, but some Americans are delaying their shots in a bid for maximum efficacy.

One of the most common strategies has been to aim for peak protection around the holiday season, getting boosted a few weeks before Thanksgiving, for instance. And those with fall travel plans have thought about taking the shots 2 or 3 weeks before heading out the door.

But will that end up being the right strategy? What if this year's variant appears in late November -- as the original Omicron did last year -- and is highly immune evasive? Will the delayed booster targeting BA.4/5 still protect against infection in that scenario?

Nearly a dozen experts contacted by 麻豆传媒 weighed in on their own booster plans, and there was no clear consensus on waiting versus getting the shots right away (with the exception of high-risk groups, who generally shouldn't delay, physicians said).

Jeremy Faust, MD, of Brigham and Women's Hospital in Boston and 麻豆传媒's editor-in-chief, noted that the "conventional wisdom in public health is that you can't time things like boosters."

However, he said, "if an individual is asking me whether they can wait until before a big Thanksgiving family reunion if they plan to be pretty cautious before then, most of the time my answer is that this would be fine."

The 'Get It Now' Crowd

Some physicians were adamant about getting their boosters right away.

Robert Wachter, MD, of the University of California San Francisco, believes it's a "bad strategy to try to 'time the market,'" and said he'll get his as soon as possible.

Peter Hotez, MD, PhD, of Baylor College of Medicine in Houston, said it's best to take the BA.4/5-specific vaccine now, when transmission of that variant is high.

Since it "may not be prevalent in a month ... now is the crunch time when you need protection," he said.

Hotez also cited that show a waning in protection against the more severe outcome of hospitalizations a few months after boosting, even in immunocompetent adults.

"Given that protections versus hospitalizations for these boosters may not exceed 4-5 months, yet another immunization may be required for a potential winter 2023 wave," Hotez said. "However, there is no way to know if that will look like BA.5 or something totally different, in which case the CDC may make new recommendations."

In addition, most experts agreed that older patients -- usually estimated at age 65 or 70 and up -- should get the new bivalent shots now, as should those who are immunocompromised and those with chronic conditions.

"The protection against serious illness is largely mediated by T cells, and as you get older ... your T cell response fades," said Paul Offit, MD, of Children's Hospital of Philadelphia, in an earlier interview. "So even with a mild or moderate infection, they can progress to a more severe illness. So therefore avoiding mild infection in that group is of value."

It's Okay to Delay

But Offit is not a fan of boosters-for-all. He has had three doses of mRNA vaccines, as well as a bout of COVID this summer -- thus, likely BA.5 -- so he won't be getting a bivalent booster.

"I do not plan to get another dose of SARS-CoV-2 vaccines until it is clear that people who have been primed, boosted, and naturally infected are nonetheless at high risk of serious illness when encountering the virus," he said.

Many other doctors fell somewhere in the middle, though. Most said they would get a bivalent booster, and that timing it with travel or the holidays would be fine in most cases.

John Moore, PhD, of Weill Cornell Medicine in New York City, is holding out hope that the FDA will authorize Novavax as a booster shot, since he was enrolled in the phase III trial for the vaccine. Ideally, that happens at least a month before he has international travel plans starting in mid-November.

Leana Wen, MD, of George Washington University in Washington, D.C., said that people who've had a booster or were infected in 2022 "can probably wait and time their next shot to before the holidays."

Wen had COVID in May, on top of the Johnson & Johnson single-dose vaccine and a Pfizer booster in fall 2021. "If I didn't have COVID in 2022, I would get the booster now," she said. "Because I had COVID pretty recently, I'll look to get the updated booster probably in early-mid October to time it closer to the holidays."

Timing the shot a few weeks before the holiday season or travel could offer an antibody boost that protects against infection. Generally, antibodies have been shown to wane after about 10 weeks -- so a boost theoretically gives the best protection against infection for about two-and-a-half months.

That's true unless a new variant pops up that can evade those antibodies. Right now, BA.5 accounts for 87.5% of cases in the U.S., with BA.4.6 coming in at 9.2% and growing, . The bivalent vaccine is designed to target those variants.

But if a new variant comes up unexpectedly, it remains to be seen whether timing a booster will still confer optimal protection against infection.

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