Covid-19 Case Counts Have Been Spiking for Weeks. Why Aren’t Deaths?
Experts say a handful of variables explain the apparent disconnect between cases and deaths.
By Markham Heid, July 13.2020
[in ELEMENTAL, your life, sourced by science. A new Medium publication about health and wellness]
Medical staff push a stretcher with a deceased Covid-19 patient to a car outside of the
United Memorial Medical Center on June 30, 2020 in Houston, Texas. Photo: Go
After slowly gathering momentum during the first quarter of the year, the number of U.S.
Covid-19 cases and deaths surged in early April. By the middle of that month, more than
30,000 Americans were testing positive for the novel coronavirus every day, and roughly
2,500 were dying, according to figures from the U.S. Centers for Disease Control and
But then, for a time, that initial wave seemed to be breaking. Daily case counts declined
as spring turned into summer. Deaths fell steadily. But these encouraging trends didn’t
last. A second wave of cases — or maybe just a resurgence of the initial wave — began
around the middle of June. Case counts have since increased sharply and show no sign
On July 9, there were nearly 65,000 new daily cases of Covid-19 — roughly double the
late-April average. But deaths have not followed suit. While the last week has witnessed
an uptick in deaths from the June nadir, line graphs of deaths are no longer mirroring the
line graphs of new cases.
That may change any day. There is usually a one- or two-week lag between a rise in cases
and an associated rise in deaths, says Stephen Morse, PhD, a professor of epidemiology
and infectious disease at Columbia University’s Mailman School of Public Health. And in
some of the newly hard-hit states, including Texas and Arizona, deaths have begun to
But given the mid-June timing of the caseload spike, we’re now well beyond the one-totwo-
week lag period that Morse described. And, according to a news report from the
American Medical Association, the virus’s springtime peak saw roughly 2,500 deaths for
every 30,000 new diagnoses. The most recent figures reveal a much more encouraging
ratio — one on the order of 1,000 deaths per 60,000 new diagnoses.
So what explains the apparent disconnect between cases and deaths? Expanded testing
capacity may be one contributing factor, although alone it can’t account for the size of the
discrepancy. Experts say a handful of variables may be at play.
“We’ve also learned that a lot of people are dying from abnormal clotting, and
we’re now able to prevent some of those deaths with protocols for
Shifting demographics — and maybe an evolving virus
Morse says that recordkeeping related to Covid-19 is “flawed” in several ways and that
these flaws make it hard to decipher the truths behind the numbers.
“Some states or localities restrict [testing] mostly to people with symptoms that look like
Covid-19 while other states will test anyone who asks for it,” he explains. At the same time,
he says that some states may be counting as “cases” only those who actually test positive
for SARS-CoV-2 while other states may include people that a clinician diagnoses based
on symptoms. “So we don’t even know what the actual baselines are,” he says.
Despite those cautions, he says that there are reasons to think that the cases-deaths gap
is legitimate. For one thing, he says that young people — those under 35 — seem to make
up a higher proportion of the recent Covid-19 cases. “There’s a preponderance of infection
among younger people as they’re the ones going out and are perhaps a bit blasé,” he
says. Meanwhile, he says that “the older and more vulnerable” may now be more likely to
stay home and play it safe.
If true, this could explain why death counts are down. Age is an established risk factor for
death due to Covid-19. According to a new, large-scale study published July 8
in Nature, adults in their eighties are at least 20 times more likely to die of Covid-19 than
adults in their fifties and hundreds of times more likely to die than someone under the age
of 40. If younger people make up the bulk of the new Covid-19 cases, it follows that fewer
of them would die from the disease.
Across the board, experts say that there’s not yet any hard evidence that the
virus or its associated disease is growing milder.
Improvements in clinical care may also explain the lower rates of death. “We know a lot
more about how to treat it than we did in March,” says John Swartzberg, MD, clinical
professor emeritus of infectious diseases and vaccinology at the University of California,
Berkeley School of Public Health.
For example, Swartzberg says that putting some patients in the prone position — lying on
their stomachs — seems to improve the amount of oxygen they take in whether they are
breathing on their own or via a ventilator. Along with these sorts of care insights, doctors
have found that certain drugs improve outcomes. Research has shown that the antiviral
drug remdesivir can reduce the risk of death in some patients, and Swartzberg says that
corticosteroids are another class of drug that has proven to be beneficial. “We’ve also
learned that a lot of people are dying from abnormal clotting, and we’re now able to prevent
some of those deaths with protocols for anticoagulation [treatments],” he says.
It may also be the case — though this is far from certain — that the virus itself is
weakening. “This is speculative, but another explanation could be that the circulating
strains [of the virus] have changed,” says Lee Riley, MD, a professor and division head of
infectious diseases and vaccinology at UC Berkeley.
Riley says that, over time, infectious pathogens mutate. While these mutations may make
a virus more transmissible — something that could explain escalating case counts — they
also frequently render viruses less pathogenic, meaning the resulting disease is less
severe, he says. Why does this happen? If a pathogen kills too prodigiously, it runs out of
Just last week, a new study in the journal Cell found that, yes, the novel coronavirus
seems to be mutating. A new and dominant “variant” of the virus has emerged, the authors
of that study told CNN, and it appears to be more infectious (easier to spread) than its
predecessor. Columbia’s Morse mentions this new research. Like Riley, he says that if the
virus is mutating, it may also be growing milder. “That’s usually what happens,” he adds.
“It’s a false narrative to take comfort in a lower rate of death.”
But the new Cell study did not find that the virus is weakening. And, across the board,
experts say that there’s not yet any hard evidence that the virus or its associated disease
is growing milder.
They also say that the apparent decline in the lethality of Covid-19 is no reason for the
public to let down its guard or abandon any of the lifesaving, virus-confounding safety
measures that health authorities have been recommending for months — measures like
wearing masks or social distancing. “We know how to control this,” Swartzberg says.
“People just aren’t doing it.” Also, doctors warn that in some cases, the disease may cause
lasting harm in those who survive.
“It’s a false narrative to take comfort in a lower rate of death,” said Anthony Fauci, MD,
director of the National Institute of Allergy and Infectious Diseases, during a conversation
last week with Sen. Doug Jones of Alabama. There are too many unknowns — and too
many established risks — to take any chances with the coronavirus. “Don’t get into false
complacency,” Fauci added.