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The new coronavirus spikes, explained

Some states are seeing Covid-19 spikes. Here’s what we know.

A nurse and patient at a Covid-19 testing center at the Navajo Nation town of Monument Valley, Arizona, on May 21.
Mark Ralston/AFP/Getty Images
Dylan Scott covers health care for Vox. He has reported on health policy for more than 10 years, writing for Governing magazine, Talking Points Memo and STAT before joining Vox in 2017.

In many parts of the United States, Covid-19 appears to be surging.

It is a grim reminder that the country has not beaten the coronavirus pandemic that has taken more than 110,000 American lives and locked down the country for much of the year. The number of confirmed cases in the US has now exceeded 2 million, and while new cases nationwide appear to be flat, they’re not dropping. Moreover, the national numbers obscure the state and local trends that have public health experts worried.

Christina Animashaun/Vox

The original pandemic epicenters — namely, the New York City area and a couple neighboring states like New Jersey — have seen a steady decline in cases and deaths since a mid-April peak. But new hot spots are emerging.

Arizona, for one, is seeing increased hospitalizations, more tests are coming back positive for Covid-19, and the rate of new infections as a share of the state’s population is quite high. Outbreaks are picking up in parts of the country that were spared the worst of the pandemic initially because, first, they were lucky the virus did not arrive there early and, second, they instituted social distancing policies before their outbreaks could grow out of control.

But even if lockdowns slowed the coronavirus, they could not stop it completely, and the virus continued to seep into more and more of the country. Some states are starting to see a worrying combination of trends in their Covid-19 data: Not only are case numbers rising, but hospitalizations are increasing and the share of tests that come back positive has gone up, all of which suggest the coronavirus is spreading in the community.

Yet at the same time, states are relaxing their stay-at-home orders, businesses are opening, and people are socializing. The protests against police violence could also have been vectors for Covid-19 spread, though it is still too early to be sure how significant their effect will be.

Renewed spread, in a country that seems committed to reopening its economy to alleviate the financial pain of the lockdowns, could put the US on a dangerous path.

“In the face of increasing numbers of case counts, the continued relaxation will only provide more opportunity for community transmission,” William Hanage, an epidemiologist at Harvard University, told me. “The virus is getting highways along which to transmit.”

There is not one coronavirus pandemic in the US, but many. Some places are finally seeing relief after the virus took a catastrophic toll. But elsewhere, the situation appears to be getting worse.

Where coronavirus spread is getting worse

Public health experts are worried about the trend lines in some areas because the coronavirus is perfectly built to cause a health care crisis, even if local health systems are not yet in crisis mode. Once people are infected with Covid-19, it takes about a week for them to show symptoms. But they are still contagious before then, unwittingly exposing more people to the virus. And once the symptoms start — they get a fever, or develop a dry cough — it can take another week or so for them to be sick enough to be hospitalized.

Hospitalizations are, in other words, a lagging indicator. But once hospitals exceed capacity, it’s already too late; they are effectively guaranteed to endure several difficult weeks after that point. People arriving in hospitals were infected two weeks or so earlier. The virus continued spreading in the interim, infecting more people. It takes time for a case to become serious enough that the patient must be hospitalized. So the next wave of those newly infected won’t show up at a hospital for a couple more weeks.

It’s a vicious cycle. That’s why the public health community was so alarmed when a major Arizona hospital system warned this week their ICU units were filling up and ventilator use had quadrupled since mid-May.

Arizona seems the likeliest candidate to become a new Covid-19 hot spot. The state’s new Covid-19 cases are up more than 200 percent over the last two weeks, according to the Covid Exit Strategy dashboard.

Some of that spike is probably the result of more testing. But what’s so concerning is that the positive test rate is also increasing at the same time, up from less than 8 percent at the end of May to nearly 14 percent now. As I wrote earlier this week, that trend “suggests the virus is actually spreading, not just that more tests happen to be finding more cases.” In new cases per million residents, another means of measuring whether spread is getting worse, Arizona has the highest rate in the country.

And hospitalizations are up. On May 10, 713 people were in the hospital in Arizona with Covid-19, according to the University of Minnesota’s hospitalization tracking project. On June 10, nearly 1,300 people were. The number of people currently on a ventilator is also higher; it was less than 200 a month ago but today is approaching 300.

Arizona might be the most extreme case in terms of worrying trends, but at least six other states share a similar profile:

  • Arkansas (cases up 113 percent in two weeks, positive test rate increasing, current hospitalizations up from 64 on May 10 to 181 on June 10)
  • Florida (cases up 87 percent in two weeks, positive test rate increasing, the state does not report current hospitalizations)
  • North Carolina (cases up 62 percent in two weeks, positive test rate increasing, current hospitalizations up from 442 on May 10 to 780 on June 10)
  • South Carolina (cases up 93 percent in two weeks, positive test rate increasing, the state does not routinely report current hospitalizations but there was a reported recent spike)
  • Texas (cases up 53 percent in two weeks, positive test rate increasing, current hospitalizations up from 1,626 on May 10 to 2,153 on June 10)
  • Utah (cases up 126 percent in two weeks, positive test rate increasing, current hospitalizations up from 93 on May 10 to 130 on June 10)

This is not a second wave. These places are experiencing their first significant upswing in Covid-19 cases because they had constrained the virus by adopting stay-at-home orders and other distancing measures before their outbreaks grew out of control. Early research suggests that lockdowns have significantly suppressed Covid-19’s spread.

Other states — California, Kentucky, and Oregon, to name a few — also have trends worth watching, but their signals are more mixed. California, for example, has seen cases rise by 20 percent in two weeks, but the positive test rate is little changed and hospitalizations are actually flat from a month ago. Oregon has seen a much steeper increase in cases, up 146 percent in 14 days, but its rate of new cases per million people is quite low (22) compared to Arizona (150). Kentucky’s positive test rate is flat, and new cases per million people is mild despite a 62 percent jump in cases over the last two weeks.

While these places are seeing their cases climb, the national Covid-19 curve looks like a plateau, with 21,894 new cases on June 1 and 20,839 new cases on June 10. That’s because other parts of the country — particularly the Northeast, which endured the worst Covid-19 outbreak in the early weeks of the pandemic — are seeing their numbers drop.

But nobody should rest easy yet, because even as cases rise in some places, most of the country is relaxing social distancing and reopening the economy.

Reopening the economy too quickly could worsen the coronavirus’s spread

It is difficult to ignore that the places seeing surges in Covid-19 cases began to reopen businesses and other public spaces a few weeks ago. Because of those reporting lags that are innate to the virus, any changes in spread would only become evident now.

“The early opening with insufficient public concern for behavior change will undoubtedly lead to more problems ahead,” David Celentano, who leads the Johns Hopkins University’s epidemiology department, told me.

Arizona rolled back its stay-at-home order on May 16. North Carolina relaxed its order on May 22. Some of the other emerging hot spots — Texas, Arkansas, etc. — have been open for business since the beginning of May. Experts point out we are now a few weeks out from Memorial Day, which may have served as an unofficial end to self-quarantine for many people in the states where shelter-in-place is no longer in effect.

We should be cautious about interpreting the surges as a clear sign that reopening is increasing spread. Correlation is not causation. There are acute outbreaks in prisons and meat-packing plants that explain part of the spike.

And not every state that’s eased its distancing policies has seen a dramatic deterioration in its Covid-19 numbers. Georgia, for example, seems to be holding up okay after allowing businesses to reopen; cases and positive test rates are up slightly but not to the degree of Arizona or Utah.

People I spoke with in these states said some increase in spread was expected; it might even be considered an acceptable trade-off for getting people back to work. Hospital capacity may be down, but that partly reflects an increase in non-Covid-19 patients now that elective surgeries have resumed.

Experts are still concerned. Texas has been seen as a leader in reopening; it never had a statewide stay-at-home order and businesses began reopening on May 1. But whatever the exact cause, the new trends in the state are troublesome.

“There is little doubt in my mind that the recent increase is also a result of more community spread,” Thomas Giordano, who leads the infectious disease program at the Baylor College of Medicine, told me. “We need to get this right, and currently the numbers aren’t looking so good.”

And to repeat one more time for good measure, Covid-19 data is always a week or more behind whatever the situation on the ground is. Spread is increasing and social distancing is easing, which could accelerate spread even more before we realize the full extent of the problem. That is the danger experts worry about right now.

“If cases are increasing under current conditions, you are not going to slow things down by giving the virus more opportunities,” Hanage said.

It’s too soon to know how much the George Floyd protests spread Covid-19

The nationwide protests over George Floyd’s death, police violence, and structural racism have also been met with concerns that they would become superspreading events.

At the protests, thousands of people congregated in close quarters and, though mask-wearing was common, it was not universal. Many public health experts lent their support to the protests, citing the toll taken on black Americans’ health across US history because of slavery and racism, but there seemed to be a real risk that these protests organized and attended by black activists would simply deepen the racial disparities in the coronavirus pandemic. Black Americans are already getting sick and dying from Covid-19 at higher rates than white Americans.

According to the experts I spoke with, however, it is simply too early to know whether the coronavirus will spread widely because of the protests. And it is worth remembering the differences between outdoor and indoor exposure, the latter being much more dangerous; it could end up being the case that people got infected because they were arrested and put into a police van or jail cell with other people, not because they were outside protesting in a big crowd.

Regardless, it’s only been about two weeks since the protests in Minneapolis grew into a national movement; new cases and any other worrying trends in the data would just now be starting to surface and may not be perceptible. For now, the trend lines in Minnesota show new cases dropping and the positive test rate is down, according to the Covid Exit Strategy dashboard.

Even if some of the places with large protests see a spike in Covid-19 cases, it will be difficult to separate the effects of the demonstrations from the effects of reopening. Minnesota, for example, relaxed its stay-at-home order on May 18 and started allowing restaurants to open again on June 1, coinciding almost exactly with the protests.

“Given that it took about a month after opening to start to see a clear increase in cases, we probably expect that any uptick coming from the protests wouldn’t be visible for a few more weeks,” Ellie Murray, an epidemiology professor at Boston University, told me. “But it’s also going to be difficult to tease out how much of any uptick is related to protesting versus other opening-related changes in behaviors.”

And as a matter of scale, widespread changes in social distancing policies or people’s behavior are likely to have a larger effect than the acute impact of a few days of protests.

“As states open up, the total number of risky contacts that are made in the population as a whole will outnumber those made at the protests,” Hanage said. “I expect there will be some retrofitting of disease in the future to the presence of a protest, but that’s not really responsible.”

The trend lines are real enough and worrying enough, in other words, without apportioning blame on the protesters. All kinds of risky behaviors are becoming more common.

The more people take precautions — wearing masks, washing hands, avoiding contact when possible — the more difficult it will be for the coronavirus to spread. But it should be clear by now: The pandemic is not over.


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