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The increase in U.S. coronavirus cases shows a change in who gets sick

When COVID-19 cases began to rise once again in the United States this spring, it may have felt like a déjà vu, a repeat of the first months of the pandemic. Although now cases are starting to fall in many, but not all hot spots, the country continues to see more than 50,000 new cases a day, and for a few days in mid-April, those numbers topped 70,000, according to the Centers of Disease Control and Prevention of the United States. This may seem more manageable than the more than 200,000 days of cases in December and January, but the latest figures are comparable to those in the accounts during last summer’s rise.

This time, however, the demographics of many of the people who get sick are different: although they vary by state, they are usually younger and still at risk because they are not yet vaccinated. They appear to be driving the new wave over more transmissible coronavirus variants, especially a so-called B.1.1.7. And, while companies continue to reopen and vaccination efforts are undemanding, public health experts are concerned that the same communities that were vulnerable throughout the pandemic may be hit again.

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New cases by the numbers

In the past year, demographic trends among individuals infected with COVID-19 have shown that adults over the age of 65 were more likely to die from the disease. Black residents, Latinos and Hispanics, and other minority groups are more likely to get sick and face serious illnesses. Now, however, vaccinations protect the majority of older people, while many minority communities and younger yet unvaccinated adults, those under 50, remain vulnerable to infection.

And this younger crowd is not only suffering from asymptomatic or mild cases of COVID-19: a majority of those hospitalized are now younger adults compared to their share of total hospitalizations from previous months. Nationwide, about 9,000 COVID-19 patients under the age of 50 were admitted to hospitals in the second week of April, compared to about 6,000 people in that age group a month earlier – while admissions for patients over the age of 60 remained at constant levels since late February.

This trend is most pronounced in states with increasing numbers of cases. Michigan, for example, saw about 1,000 new adult patients under the age of 50 admitted to the hospital with confirmed cases of COVID-19 in the week ending April 9, compared to fewer than 300 patients in that age group in the first week of 2021, during the peak of the winter wave. Younger patients accounted for only 17 percent of all patients in Michigan during that previous week, but 29 percent three months later.

Vaccines help. However, while younger adults have come to the forefront of the vaccine line in recent weeks alone, many eligible residents in minority communities have struggled to get a vaccine since implementation began. Survey data show they are willing (if not more so) to be vaccinated than their white neighbors, but have trouble accessing the shots. Most states, for example, vaccinated at least 25 percent of their white populations, according to the Bloomberg vaccine tracker, but only 12 states vaccinated the same part of their black populations as on April 26. And only nine states have achieved that. landmark with Hispanic / Latino populations.

These figures are troubling, says Enrique Neblett, a behavioral health expert at the University of Michigan at Ann Arbor and associate director of the Detroit Community-Academic Urban Research Center. Neblett has seen access problems disrupt first-hand vaccination through his work in Detroit. “People on the ground (community organizers in Detroit) were saying things like they didn’t see much doubt, but it was more about vaccine access, transportation, and working hours,” he says. These barriers are common in already vulnerable communities, leaving people living there more susceptible during this new wave, he says.

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That vulnerability has consequences. During the winter of 2020, racial and ethnic disparities in COVID-19 hospitalization rates became less severe compared to the first months of the pandemic. But Neblett says he is concerned that lack of access to the vaccine, along with long-standing differences in access to health care, employment and other institutional and cultural factors that have caused these COVID-19 disparities, could reverse this pattern in the coming months ( SN: 10/10/20).

“It’s very hard to say, but I think if we don’t get this, it’s very likely that we’ll start to see those disparities increase again,” he says.

Role of new variants in increasing cases

One of the reasons for the increase in cases is that the coronavirus is mutating, creating variants of the original SARS-CoV-2 virus that initially sowed infections. B.1.1.7, a variant first identified in the United Kingdom, was causing more cases in the United States than any other version of the coronavirus, with an estimated 59 percent of cases nationwide as of April 10, according to the CDC.

COVID-19 vaccines currently used in the United States are demonstrably effective against B.1.1.7, which means you may be protected against serious disease even if you get sick with this variant. But it is estimated that B.1.1.7 is between 40 and 70 percent more transmissible, so it can spread more easily among people who have not yet received a vaccine (SN: 19/04/21).

“There are almost two pandemics,” says Will Lee, head of science at genomics company Helix, who has been working with the CDC to track variant cases through genetic testing and sequencing. "One of them is the original SARS-CoV-2 and the other, which is B.1.1.7." Since B.1.1.7 is much more communicable, Lee says, we can think of it as a new disease, with patterns of infection and outbreaks of its own.

Lee says the UK winter outbreak shows how cases of B.1.1.7 may increase in one region although cases caused by older variants are declining. The increase in Michigan cases follows a similar pattern. From mid-March to mid-April, B.1.1.7 accounted for 70 percent of cases in the state, which identified its first case with the variant only in mid-January. And the variant has a clear impact: Michigan accounted for 10 percent of new COVID-19 cases nationwide the week of April 8-14, while the state accounted for only 3 percent of the nation’s population. State hospitals have canceled elective surgeries to deal with the wave of patients with COVID-19. And Michigan isn’t the only state with a B.1.1.7 problem: nearly three out of four cases in Tennessee, Minnesota and Florida are now caused by B.1.1.7, CDC reports.

Meanwhile, other parts of the country are dealing with other variants that are not so well studied. In California, 39 percent of cases are caused by B.1.427 / B.1.429, a couple of more transmissible variants that do not respond to medications that doctors have been using to treat COVID-19. California variants also spread easily in Arizona (31 percent of cases), Colorado (25 percent) and other Midwestern states. A variant grown at home in New York has also been identified and is causing more than 1 in 10 cases nationwide.

It takes time to do the genetic testing needed to identify these variant cases – and the United States is still struggling to expand its national surveillance efforts – so these data are a snapshot from mid-April. Since then, new outbreaks of B.1.1.7 and other variants have likely grown.

That said, variants are not entirely to blame for the sharp rise in cases. “I don’t think there’s ever a factor that guides everything we see,” says Natalie Dean, a biostatistician at the University of Florida in Gainesville. While B.1.1.7 and other emerging variants may accelerate case increases, Dean points out, there have been other factors that have contributed in recent months, such as the reopening of businesses and behavioral changes that place people in closer places, stimulating the spread of the virus.

States from California to Connecticut have reduced mask mandates, indoor capacity limits and other restrictions. These reopenings can cause outbreaks in larger communities as people who become infected in a restaurant or at a football game interact with other people who have not chosen to enter a more risky environment (SN: 18/06/20).

Prisons and jails are also particularly likely to cause outbreaks in their surrounding communities. Many incarcerated Americans have not yet been vaccinated, unlike residents in nursing homes, another group living nearby. The Bellamy Creek Correctional Center, a prison in Michigan, was one of the main foci of B.1.1.7 in February, which sowed other cases in the state.

Still, in the midst of this latest increase, there is one crucial metric that has remained mercifully low: the mortality rate. The daily average of deaths has remained below 1,000 since mid-March. This number suggests in part that, so far, vaccines protect many of the most vulnerable.

But that is not enough. In order for us to control the new rise in cases, the United States will need enough people vaccinated to stop new infections. Dean sees Michigan as a warning to other states of how quickly new outbreaks can occur, but says it’s not a lost conclusion.

“Every day we vaccinate more people we make that (trajectory) less likely,” he says.

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