美国国家公共电台 NPR--A new dominant omicron strain in the U.S. is driving up cases — and reinfections（在线收听）

A new dominant omicron strain in the U.S. is driving up cases — and reinfections

Transcript

For much of the pandemic, the only silver lining to coming down with a case of COVID-19 was that you likely wouldn't catch it again for a while (though there isn't exactly a definitive answer on how long that period of immunity typically lasts).

Increasingly, however, more people appear to be contracting the virus multiple times in relatively quick succession, as another omicron subvariant sweeps through the U.S.

The BA.5 variant is now the most dominant strain of COVID-19 in the country, according to the Centers for Disease Control and Prevention. And while it's hard to get an exact count — given how many people are taking rapid tests at home — there are indications that both reinfections and hospitalizations are increasing.

For example: Some 31,000 people across the U.S. are currently hospitalized with the virus, with admissions up 4.5% compared to a week ago. And data from New York state shows that reinfections started trending upwards again in late June.

Dr. Bob Wachter, the chair of the Department of Medicine at the University of California, San Francisco, says BA.5 is highly transmissible and manages to at least partially sidestep some of the immunity people may have from prior infections and vaccinations.

"Not only is it more infectious, but your prior immunity doesn't count for as much as it used to," he explains. "And that means that the old saw that, 'I just had COVID a month ago, and so I have COVID immunity superpowers, I'm not going to get it again' — that no longer holds."

So just how worried should you be, especially if you're vaccinated and taking precautions like wearing masks in crowds? Here's what some public health experts make of the latest surge.

Is BA.5 more dangerous?

So far there is no evidence that this variant causes more serious illness. And infectious disease experts say that even though new infections are on the rise, the impact of BA.5 is unlikely to be on the scale of the surge we saw last winter — in part because the country is better equipped to manage it.

The U.S. is averaging about 300 deaths a day, compared to 3,000 last winter. Dr. Anna Durbin, a professor at the Johns Hopkins University School of Medicine, says the combination of prior infections and vaccinations is still protective, and COVID-19 treatments are better.

"Most people have some underlying immunity that is helpful in fighting the virus," she explains. "We have antivirals ... And I think that because of that ... we're not seeing a rise in deaths. And that's very reassuring. It tells me that even this virus, even BA.5, is not so divergent that it is escaping all arms of the immune system."

She adds that new booster shots specifically targeting omicron — which could roll out as soon as this fall — should also be helpful in preventing serious illness and deaths.

Are there long-term consequences for people who get COVID-19 multiple times?

Findings of a pre-print study published in June suggest that people who get sick multiple times may have a higher risk of long-COVID symptoms.

Dr. Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis, looked at thousands of cases of reinfection and saw a wide range of problems in the months that followed: certain respiratory conditions, cough, shortness of breath, fatigue, brain fog and other conditions including metabolic disease, cardiac disease, kidney disease and diabetes.

"Altogether, we concluded that reinfection contributes to additional risk," Al-Aly says. "So even if you're vaccinated ... it's absolutely best to avoid reinfection."

And a study published last week in the journal Cell concludes that repeat infections are likely.

Researchers studied blood samples from people who had been vaccinated and boosted, and they found they had a reduced ability to neutralize the BA.5 virus, compared to prior sub-variants, BA.1 and BA.2.

In addition, blood from people who had breakthrough infections from BA.1 also showed reduced neutralization, "suggesting that repeat Omicron infections are likely in the population," the authors conclude.

What can people do to protect themselves?

There are steps you can take to reduce your exposure to the virus, like masking up in crowded indoor spaces. Here's how to step up your mask game.

Plus, children under the age of 5 are finally eligible to get vaccinated (and while many parents are hesitant, public health experts are encouraging them not to wait any longer). And adults ages 50 and older, as well as those over 12 with certain underlying conditions, can get a second booster shot.

And, if you already have plans to travel or attend gatherings this summer, check out these tips for protecting yourself outdoors, improving indoor airflow and what to do if you get sick while on vacation.