Global death rates fall despite more infections
Reasons could include younger people bearing brunt of new cases, growth in tests
After working for three months straight at Detroit Medical Center, Said El Zein noticed that the coronavirus patients who began arriving in May appeared less sick than those who came before.
More than 4,000 miles away in northern Italy, researcher Chiara Piubelli was struck by the same thing.
Rafael Cantón, an infectious disease specialist in Madrid, also marveled at the change. “It’s totally different,” he said last month of the falling admissions at his medical center, noting that only 130 of 1,000 beds were full despite surging infections — a huge change from early spring, when every bed was occupied.
Death rates from the coronavirus are lower in hot spots around the world, even as new infections accelerate in what may be the pandemic’s next wave. Scientists are confident the change is real, but the reasons for it — and whether it will last — are a matter of debate.
“Is this a trend or a blip?” asked Joshua Barocas, an infectious disease specialist at the Boston University School of Medicine. “Nobody really knows.”
The mortality rate of the coronavirus has been a moving target since the outbreak began.
Early reports out of China put it as high as 7 percent. But that was based mostly on hospitalized patients, and by the time the wave hit the U.S., epidemiologists believed it was closer to 2 to 3 percent. Now, factoring in asymptomatic infections, as well as mild cases that might not be part of official tallies, the Centers for Disease Control and Prevention puts the mortality rate at 0.65 percent.
Barocas emphasized that even the lowest estimates represent the potential for millions more deaths. The U.S. already has the highest number of cases in the world and the most recorded deaths of any country. Though its 330 million people represent roughly 4.25 percent of the world’s population, the country has recorded just over 20 percent of deaths from COVID-19.
Public health officials cite multiple reasons for the lower death rates: They note a shift in the demographics of who is being stricken with the virus, with younger people making up the bulk of new infections. More widespread testing is capturing a more diverse range of people and illness, and improved treatment strategies that include antivirals and steroids are saving more lives.
But some researchers speculate there may be more to the story.
One idea that has generated a lot of discussion recently, bolstered by two back-to-back studies — one by El Zein and another from Italy, presented in late September to the European Society of Clinical Microbiology and Infectious Diseases — is that social distancing and masks are reducing the level of virus people are receiving, resulting in less-severe illness.
As El Zein and other doctors in Detroit probed why their patients appeared to be less ill, they were startled to find that one indicator in particular changed dramatically over time: viral load.
Among 708 patients treated by early summer, the average viral load — a measure of the particles of virus in the body as measured by nasal swabs — fell almost on a weekly basis. In most infectious diseases, including Ebola, HIV/AIDS and hepatitis, the higher the load, the worse the outcome.
El Zein saw glimmers of hope in the findings: Could it be that the steps being taken to mitigate the coronavirus’ effects were showing success?
Monica Gandhi, an infectious diseases researcher at the University of California at San Francisco, shares that view. If the initial viral dose — known as the “inoculum” — is lower, she theorized, people’s bodies are able to fight back more effectively.
This “likely indicates an ability to control the viral infection better, and, therefore, have less severe disease,” Gandhi said.
El Zein’s findings are considered preliminary because the team still is analyzing possible confounding factors, such as differing treatments, to see if the relationship holds.
El Zein said the relationship between viral loads and deaths was so striking that he went back to the lab to check, doublecheck and then triple-check equipment and to try to figure out whether anything had changed with the procedures for collecting samples, He found no differences.
“It definitely wasn’t by chance or by mistake those numbers are going down,” he said.
“It definitely wasn’t by chance or mistake those numbers are going down.”
Said El Zein, Detroit Medical Center