As US coronavirus cases have surged to record levels, a dark question hovers in the minds of public-health experts: When will deaths follow?
In the past two weeks, daily cases have risen by about 50% compared with the two weeks before that, with a peak of nearly 55,000 new cases on July 2. Meanwhile, deaths have declined a little, from about 690 per day in mid-June to about 560 per day over the past two weeks.
There are good reasons to think that the ratio of COVID-19 deaths to cases during this second surge won’t reach the same level it hit in April. That’s primarily because increased testing is catching more mild cases, younger people make up a larger share of cases than they used to, and hospitals and doctors are better informed and prepared now.
On the other hand, it could be only a matter of time before deaths spike again. Severe COVID-19 cases progress over several weeks, and case numbers began to rise considerably only a few weeks ago.
“We’re starting to see that uptick in deaths coming now,” Dr. Theo Vos, who develops coronavirus projections for the University of Washington’s Institute for Health Metrics and Evaluation, told Business Insider.
His model predicts that the US could see more than 200,000 coronavirus deaths by November 1, with deaths starting to climb dramatically in the fall. Recently, Arizona, Florida, and Texas have seen their daily death counts rise.
“No one wants to say too early that deaths are not rising,” Dr. Howard Koh, a professor at the Harvard T.H. Chan School of Public Health, told Business Insider. “That would really be a mistake.”
Koh, Vos, and other experts suggested a handful of reasons that deaths have lagged so far. Here are the five main factors at play.
Young people represent a growing share of coronavirus cases
Dr. Jeffrey Klausner, a professor of epidemiology at the University of California, Los Angeles, said the primary reason deaths haven’t risen considerably is the changing demographics of coronavirus patients.
“Age is by far the strongest predictor of mortality,” he told Business Insider. People over 65 represented about 80% of US coronavirus deaths reported in June.
In Florida, the median age of coronavirus cases has dropped to 35 from 65 in March. Cases among people under 40 have risen in Arizona, California, Minnesota, Ohio, South Carolina, and Texas. Since coronavirus cases in young people tend to be milder, many of those cases won’t prove fatal.
“We’re all speculating that after Memorial Day, it was really the younger people who perhaps reengaged with society too soon and without the proper precautions,” Koh said.
Older people or people with preexisting health conditions, meanwhile, are more likely to still be at home, given their vulnerability to getting a severe infection.
“People over the age of 70 or 75, they’re avoiding most people, or they’re taking protective measures,” Klausner said. “Older people are saying, ‘Hey, you know, I’m not going to attend this family event,’ or ‘I’m going to keep my distance where it’s possible.'”
Increased testing is catching more mild cases
President Donald Trump has suggested that the skyrocketing case numbers are due solely to increased testing. Experts say that’s not the case — the virus is spreading rapidly in many states, most notably Arizona, California, Florida, and Texas.
But the US is testing far more now than it was a month or two ago. The country is testing 62 out of every 100,000 people per day, on average — a lower per-capita rate than Russia, Iceland, and Australia, but a higher rate than Italy and France. That could mean more mild cases are being found than at the start of the outbreak, when tests were reserved for people with severe infections.
“With increased testing, you identify more cases, hopefully in a rapid way,” Vos said.
As testing becomes widely available, people may get tested earlier in the course of their illness, leading them to seek treatment right away. That could save some lives. Most people, however, don’t show up to the hospital until their case is already severe — about 10 or 11 days after symptoms start.
Doctors are getting better at treating COVID-19 patients
A growing body of coronavirus research — paired with the development of therapeutic agents — could also be preventing some deaths.
On top of that, doctors have become savvier about treating critical cases.
For example, Koh said, physicians have discovered the benefits of proning, or placing coronavirus patients on their stomachs instead of on their backs to improve oxygenation in the lungs. They’ve also used ventilators more sparingly, or on settings with lower air pressure, to avoid damaging patients’ lungs even further.
But since there’s no slam-dunk treatment, many patients still face grim outcomes.
“There may be some effect of getting better at treating people,” Vos said. But he added that “things are trending towards much, much larger problems in Texas, Florida, Arizona, and a host of other states.”
Hospitals are more prepared for an influx of patients
More than 80% of Florida’s adult intensive-care-unit beds were occupied on Tuesday, according to Florida’s Agency for Healthcare Administration. More than 50 hospitals in the state have reported that their ICUs have reached max capacity, while another 30 have said their ICUs are more than 90% full.
Hospitals in Houston, Texas — where coronavirus hospitalizations nearly quadrupled from Memorial Day to July 1 — have started transferring patients to other cities.
Still, many hospitals have had time to prepare for new arrivals by adding beds, hiring or transferring staff members, and stocking up on personal protective equipment. Hospitals in the San Francisco Bay Area, for instance, prepared tents for coronavirus patients in March that went unused but could open if necessary.
“We will be ready if a surge does come,” Dr. Maria Raven, the chief of the Department of Emergency Medicine at the University of California, San Francisco, told ABC7 last week.
There’s a considerable lag between cases and deaths
A highly plausible and very worrisome explanation for why deaths have stayed flat, however, is that more are coming soon.
“It’s a false narrative to take comfort in a lower rate of death,” Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said during a news conference on Tuesday.
Official case numbers generally reflect infections contracted about two to three weeks prior. On average, COVID-19 patients die about 18 or 19 days after first showing symptoms. After a patient dies, it can take several days for that death to be added to the official tally.
“Deaths are a lagging indicator,” Koh said. “If somebody is infected and then has the risk of getting sick and being hospitalized and dying — that whole trajectory takes a number of weeks at least, maybe up to a month or more.”
And as coronavirus cases are detected much earlier in the course of an illness, there may be an even longer lag.
“When you start identifying people at earlier stages of a disease, it looks like they survive longer (or have the disease longer) compared to when you identify based on severe symptoms,” Eleanor Murray, an assistant epidemiology professor at Boston University’s School of Public Health, wrote on Twitter on Monday.
The unfortunate reality is that after new coronavirus cases are identified, some deaths are bound to follow.
“In places where cases are rising, hospitalizations are increasing too,” Koh said. “We will inevitably see deaths coming in such situations, unfortunately.”