Cases of Covid-19 in the United States are on the rise again. What is happening?

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

Since early January, when the United States peaked at 260,000 new cases per day on average, the number of cases has been declining more or less steadily. Tens of millions of people were vaccinated against Covid-19 in the months that followed. At the end of June, the country had an average of only 11,000 new cases per day, according to the New York Times tracker.

But as of July 13, the United States was registering about 25,000 new cases a day on average, double the number of cases just a few weeks ago.

Our world in data

So far, hospitalizations have not increased as much: they have increased only slightly, from a seven-day average of 16,500 two weeks ago to around 19,500. Likewise, deaths are still quite low: a daily average of 330 per day, compared to January, when the United States was losing more than 3,000 people per day. Both measures continue to grow, if not as fast as cases.

Confirmed cases are a leading indicator. Someone tests positive for the disease, but it can take two weeks for them to get sick enough to go to the hospital and even longer for them to die if they don’t recover. (One caveat: Testing rates have dropped significantly over the past few months, so we may not be detecting all new cases. But that only makes the increase in confirmed cases more worrying.)

It’s still true – when cases accelerate, deaths eventually accelerate – and current trends reflect this basic reality.

But this time around half the country is now fully vaccinated against Covid-19. Some of these 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 last week that nearly all of the hospitalizations and deaths from Covid-19 now reported are in unvaccinated people.

“The decoupling between cases and deaths has really happened,” Andrew Pavia, an infectious disease specialist at the University of Utah, told reporters in an Infectious Diseases Society of America briefing. this week. “We are seeing an increase in deaths, but not as much as before. “

However, as long as the virus is circulating, there are risks, especially for half of the population who have not been vaccinated. The delta variant appears to be more transmissible and virulent than its predecessors, and although vaccines appear to be resistant to it, it still accounts for a growing share of cases in the United States.

Hospitalizations and deaths are also increasingly common among young people, another distinction from previous flare-ups.

Overall, the situation is much more complicated than it was last year, when hospitalizations and deaths would rise like clockwork following an increase in cases. Here are three factors to keep in mind for the future.

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

If you haven’t been vaccinated, you don’t have protection against the coronavirus – and the increasingly common delta variant looks more dangerous than previous iterations of the virus. At present, it accounts for almost half of new cases in the United States and is expected to become the dominant strain.

As Vox’s Umair Irfan explained, the delta variant appears to be 60% more transmissible than the alpha variant first identified in the UK – which was probably already 60% more transmissible than the version of the virus first identified. times in humans.

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

“As more unvaccinated people acquire the delta variant, hospitalizations may actually increase,” David Celentano, an epidemiologist at the John Hopkins School of Public Health, told me.

Different states also have different degrees of vulnerability, with statewide vaccination rates ranging from 78 percent of fully vaccinated Vermonters to just 42 percent of Alabamians. This has translated into an increase in the number of cases: the states with the most new cases (including parts of the South, Midwest, and West) per capita all rank in the bottom half of the states in terms of vaccination rate.

Mario Tama / Getty Images

Then there’s the changing nature of the age groups affected by Covid-19: According to the Kaiser Family Foundation survey, 85% of all people 65 and over report having been vaccinated. But that percentage drops among the younger cohorts, to 66% of those 50 to 64, 59% of those 30 to 49, and 55% of those 18 to 29.

2) Vaccines protect those most vulnerable to Covid-19

These trends contain both good news and bad news. The bad news is obvious: because young people and people in some states are less likely to have been vaccinated against Covid-19, they remain more likely to contract the disease. The more so as the delta variant becomes more dominant, a higher share of them will end up in the hospital. Some will die.

According to CDC data, the share of people hospitalized with Covid-19 aged 18 to 49 has risen from 20% of the total in January to over 40% now. Americans 65 and older accounted for more than half of Covid-19 hospitalizations in January; they now represent less than 30 percent.

To be clear: Overall hospitalizations are still well below their peak, so the crude number of critically ill young people is not as large as the number of hospitalizations among older people at the height of the winter wave. But, relatively speaking, young people now represent a larger share of hospitalizations.

The good news is the flip side of this trend: those most vulnerable to death from Covid-19 enjoy much more robust protection than last year. We have known since the start of the pandemic that age, more than anything, is the best indicator of a person’s risk of succumbing to Covid-19.

This is why nursing home residents and workers were given priority when mass immunizations began in early 2021. According to an AARP analysis of federal data, nearly 80% of people residing in nursing homes were fully vaccinated against Covid-19 at the end of June.

During the pandemic, they accounted for a disproportionate share of Covid-19 deaths – 133,482 out of 608,000 total deaths in the United States. But death rates among this population slowed considerably once vaccinations took off. In early January, US nursing homes reported more than 5,000 resident deaths each week, according to federal data.

In the last week of June, nursing homes reported just 147 resident deaths. This represents remarkable progress in protecting the most vulnerable.

3) Vaccinated people can contract Covid-19, but cases are almost always mild

Covid-19 vaccines are very good, but they’re not perfect. A number of people who have been fully vaccinated will contract the coronavirus, and they may also explain part of the growing number of cases.

When the Pfizer / BioNTech and Moderna vaccines were first approved, it was the astonishing 95% efficacy rates that received all the attention. But even then, it meant that a very small number of those vaccinated fell ill.

This share will increase as the delta variant becomes more dominant; as Irfan reported, early evidence suggests that the Pfizer / BioNTech vaccine is still 80 percent effective in preventing disease. But it does mean that more people who have been vaccinated can contract the virus and experience symptoms as the variant continues to spread.

This is still a high success rate. The World Health Organization said this week that most vaccinated people who contract the delta variant have no symptoms. They may also be less likely to spread the virus because they appear to eliminate less of it, CDC deputy director Jay Butler told reporters at the Infectious Diseases Society of America briefing.

And vaccines still offer impressive protection against serious illness, which is reflected in the tiny number of vaccinated people hospitalized or dying from Covid-19.

“Rupture infections tend to be milder,” Butler said. “Even in the event of infection, [vaccination] decreases the risk of hospitalizations and death.

Rising cases are not ideal. Millions of Americans are still vulnerable to Covid-19, and a more dangerous variant of the virus is taking hold. The number of fatalities occurring each day is still equivalent to a crash of an airliner every 24 hours.

But this is a different wave from those that preceded it, with nearly 160 million Americans counting now fully vaccinated. The solution is the same as in the past six months, as Celentano told me by email: “The best way to avoid acquiring SARS-CoV-2 is to get the vaccine now!”

Otherwise, as long as the virus is circulating, there are risks.

“The more virus that circulates, the more mutations there are, and the more likely that another new variant will emerge,” Jen Kates, director of global health at the Kaiser Family Foundation, told me.

A new, more lethal, more transmissible, or more vaccine-resistant variant “would of course have more serious public health implications.”