Coronavirus Briefing: What Happened Today


The Biden administration has decided that most Americans should get a coronavirus booster shot, our colleague Sharon LaFraniere reported last night. Officials are planning to announce the decision as early as this week, with doses beginning as early as mid-September for the most vulnerable.

If you’re feeling whiplash, you’re not alone. Just over a month ago, government officials and public health experts were dubious of claims that vaccine booster shots would be necessary. That consensus has now shifted abruptly.

Why is this happening? Based on data through the end of June, the C.D.C. and public health experts repeatedly assured the public that breakthrough infections were extremely rare, and that vaccinated people were highly unlikely to become severely ill.

Then came Delta: The highly contagious variant began to sweep through the country in July, overwhelming the immune systems of unvaccinated people and also breaching the defenses of some who had received the vaccine.

“It’s so much more contagious and packs a bigger punch that a lot more vaccinated people are getting infected,” our colleague Apoorva Mandavilli said.

The vaccines are still powerfully protective. In raw numbers, so-called breakthrough infections in fully immunized people are not common, and most people who become severely sick and die of Covid-19 are unvaccinated. Still, breakthrough infections have made up a rising percentage of diagnosed cases in recent weeks, and higher percentages of total hospitalizations and deaths than expected.

Apoorva analyzed seven states that have provided the requisite preliminary data — California, Colorado, Massachusetts, Oregon, Utah, Vermont and Virginia — and found a larger percentage of vaccinated people than previously thought among those infected, hospitalized and killed by the coronavirus:

  • In six of the states, breakthrough infections accounted for 18 percent to 28 percent of recorded cases in recent weeks. (In Virginia, the outlier, 6.4 percent of the cases were in vaccinated people.) These numbers are likely to be underestimates, because many fully immunized people who become infected may not seek a test.

  • Breakthroughs accounted for 12 percent to 24 percent of Covid-related hospitalizations.

  • The number of deaths caused by breakthroughs was small, so the proportion of vaccinated people is too variable to be useful. But it does appear to be higher than the C.D.C. estimate of 0.5 percent.

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“Remember when the early vaccine studies came out, it was like nobody gets hospitalized, nobody dies,” said Dr. Robert Wachter, chairman of the Department of Medicine at the University of California, San Francisco. “That clearly is not true.”

The figures lend support to the view, widely held by officials in the Biden administration, that some Americans may benefit from booster shots in the coming months.

But there are caveats: The seven states were examined because they are keeping the most detailed data. It is not certain that the trends in these states hold throughout the country. And some rise in the proportions is expected as more people get vaccinated.

Most crucially, the newly emerging picture does not mean that the vaccines are ineffective.

“The main takeaway is that the vaccines are really and truly excellent, but they’re not a perfect shield against the Delta variant,” Apoorva said. “Vaccinated people should be careful, especially if they’re high risk.”

The C.D.C. declined to comment on the states’ numbers. The agency is expected to discuss breakthrough infections, hospitalizations and vaccine efficacy at a news briefing on Wednesday.

Our colleague Natasha Frost reports from Auckland:

New Zealand has gone into a strict three-day lockdown after a single case of the Delta variant was identified in Auckland, requiring residents to stay at home and closing all schools, public facilities and nonessential businesses.

“With Delta raging around the world,” said Jacinda Ardern, the country’s prime minister, “it was not a matter of if, but when.”

It is believed to be the country’s first case of the more contagious Delta variant outside its strict quarantine system; it is not yet known how the individual who first tested positive contracted the virus. By Wednesday morning, another four cases connected to the initial infection had been identified, including in a nurse at the country’s largest hospital, who was fully vaccinated.

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The country’s “Covid-zero” status had allowed New Zealanders to live with almost no restrictions for the past year. But just 17 percent of the population is fully vaccinated, making the country especially vulnerable.

“We are one of the last countries in the world to have the Delta variant in our community,” Ardern said. “This has given us the chance to learn from others.”

Infections have fallen in India, which endured devastating caseloads in its second wave this spring. But scientists are anxiously looking for signs of another surge that could emerge in Delta’s wake.

New laboratories are searching for dangerous new variants or mutations in the coronavirus. They have stepped up testing, to over 3,600 samples per month, from 134 samples in December last year.

Still, India is far short of its goal to institute comprehensive genome sequencing, hindered by limited sampling capabilities. Only 8.5 percent of Indians are fully vaccinated.

Some hope that the sheer contagiousness of the Delta variant means that many people have already caught it and developed a measure of protection. A recent survey found that two-thirds of blood samples had antibodies, compared with about one-quarter in December and January. In some states, as many as three-quarters of samples carried antibodies.

But scientists cautioned that the survey, with a small sample size of 36,000, shouldn’t be read as an indication that India is out of the woods. Even if the numbers are accurate, they suggest that 400 million Indians remain vulnerable to Covid-19.

Our whole family were all vaccinated as soon as it was possible to do so, yet our grandson, who has been working in a day camp this summer, brought home the Delta variant. Luckily, our daughter-in-law is a scientist and got everyone tested as soon as he had a runny nose. Our grandson and his mom were positive, our son and granddaughter were negative and we are waiting to find out if my husband and I are positive. — Beda Herbison, Seattle

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