US Covid-19 cases are rising again. What’s going on?


Covid-19 cases are on the rise in the United States again. But this time, the story is more complicated than it was in previous waves.

Since early January, when the United States hit a peak of 260,000 new cases every day on average, case numbers have been in more or less constant decline. Tens of millions of people were inoculated against Covid-19 in the following months. By late June, the country was averaging just 11,000 new cases per day.

But as of July 18, the US is seeing more than 31,000 new cases daily on average, nearly triple the case levels of just a few weeks ago.

Our World in Data

So far, hospitalizations have not increased as much: They’re up about one-third compared to two weeks ago. Deaths, likewise, are still comparatively low: a seven-day average of 258, compared to January when the US was losing more than 3,000 people per day. Both measures are still growing, if not yet as rapidly as cases.

Confirmed cases are a leading indicator. Somebody tests positive for the disease, but it may take two weeks for them to become sick enough to go to the hospital and even longer for them to die if they do not recover. (One caveat: Testing rates have dropped significantly in the past few months, so we may not be detecting every new case. But that only makes the rise in confirmed cases more concerning.)

This is still true — when cases accelerate, so do deaths, eventually — and the current trends reflect that basic reality.

But this time, about half of the country is now fully vaccinated against Covid-19. Some of those people could still contract the virus, but their illness is much more likely to be mild if they have received the vaccine. The Biden administration announced in early July that nearly all the Covid-19 hospitalizations and deaths being reported are of unvaccinated people.

“The decoupling between cases and deaths has really occurred,” Andrew Pavia, who specializes in infectious diseases at the University of Utah, told reporters at an Infectious Diseases Society of America briefing last week. “We’re seeing an increase in deaths but not nearly to the degree previously.”

Still, so long as the virus is circulating, there are risks, especially to the half of the population who haven’t been vaccinated. The delta variant appears more transmissible and virulent than those that came before it, and, while the vaccines seem to be holding up well against it, it is still accounting for a bigger and bigger share of cases in the US.

Hospitalizations and deaths are also becoming more prevalent among younger people, another distinction from prior surges.

All in all, the situation is much messier than it was last year, when hospitalizations and deaths would grow like clockwork following a rise in cases. Here are three factors to keep in mind going forward.

1) Unvaccinated people are still very vulnerable to Covid-19

If you have not been vaccinated, you do not have protection against the coronavirus — and the increasingly prevalent delta variant appears more dangerous than previous iterations of the virus. Right now, it accounts for nearly half of new cases in the US, and it is expected to become the dominant strain.

As Vox’s Umair Irfan explained, the delta variant appears to be 60 percent more transmissible than the alpha variant first identified in the United Kingdom — which was likely already 60 percent more transmissible than the version of the virus first identified in humans.

Early evidence is mixed, but some suggests the delta variant may also be more virulent: A study conducted in Scotland found that people who had contracted the delta variant were twice as likely to end up in the hospital, though the death rate did not appear to be significantly worse.

“As greater numbers of non-vaccinated persons acquire the delta variant, hospitalizations may indeed rise,” David Celentano, an epidemiologist at the John Hopkins School of Public Health, told me.

Different states also have different degrees of vulnerability, with vaccination rates by state ranging from 78 percent of Vermonters being fully vaccinated to just 42 percent of Alabamians. That has translated to the growth in cases: The states seeing the most new cases (including parts of the South, Midwest, and the West) per capita all rank in the bottom half of states in vaccination rates.

A health care worker passes out water to people waiting in the observation area after receiving a dose of a Covid-19 vaccine on March 30, 2021, in Apple Valley, California.
Mario Tama/Getty Images

Then there is the changing nature of which age groups are being affected by Covid-19: According to the Kaiser Family Foundation’s polling, 85 percent of all people 65 and over say they have been…

Read More:US Covid-19 cases are rising again. What’s going on?

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