- It seems like, but isn’t, as high as 4%
- Most likely, it’s around 1.4 – 1.6%
One of the most reported and widely varying statistics associated with COVID-19 is its mortality rate. Mortality rates for the disease depend on a number of factors (which we’ll examine in more detail), but there is a way to determine overall mortality, or naive mortality. The math is relatively simple: the number of deaths divided by the number of people infected.
‘Naive’ mortality is 4%
Taking the data on reported cases against deaths provided by the John Hopkins Coronavirus Resource Center, the naive or crude mortality rate is currently around 4 percent. Earlier in March, that number was proposed to be 3.4-3.6 percent, though many of those calculations were based on numbers from the World Health Organization. We’ll be updating that number often, though, and not only because we want this post to be as accurate as possible, but because the problem with a naive mortality rate is that currently reported cases could result in deaths, changing the percentage entirely.
Problems with naive mortality rate
It’s hardly surprising that different expert organizations are reporting varying numbers. Naive, or crude, mortality rate is a difficult number to calculate because the quantities are constantly changing. There’s also the issue of the likelihood that not all cases are being counted. Just like we don’t know how many reported cases will result in deaths, we also don’t know how many cases there truly are or were.
As has been widely reported, COVID-19 can present as incredibly mild, so it’s possible that cases that didn’t end in death were and are underreported. That would obviously also skew the numbers. According to a study released in March in the journal Science, researchers estimate 86% of all infections in China were undocumented before the January travel restrictions were enacted.
Actual mortality is currently around 1.4-1.6%
It’s incredibly difficult to quantify actual mortality as the numbers are constantly changing, but a yet-to-be-peer-reviewed report from the University of Bern that looked at data from China places it at 1.6 percent. Another preprint report from epidemiologists from Harvard and the University of Hong Kong determined it to be 1.4 percent.
Mortality increases steeply with age
Breaking outside of the naive mortality rate dilemma, a more accurate understanding of COVID-19’s damage could come from breaking down how it’s affecting different age groups. As in China, the U.S.’s mortality rate is highest among the elderly (those aged 65 or older). In China, 80% of deaths from COVID-19 were attributed to people 60 years or older. In a CDC report released March 18, the U.S. appears to be following a similar trajectory. The mortality rates for the following groups are:
- In people 85 or older: 10-27%
- In people 65-84: 3-11%
- In people 55-64: 1-3%
- In people 20-54: less than 1%
- In people 19 or younger: no fatalities
Mortality increases steeply with risk factors
Mortality rates don’t only vary between age groups, they also change depending on risk factor—things like immune deficiencies or other illnesses. Here are the mortality rates according to China’s Centers for Disease Control for people suffering from different diseases:
- Cardiovascular disease: 10.5%
- Diabetes: 7.3%
- Chronic respiratory disease: 6.3%
- High blood pressure: 6%
- Cancer: 5.6%
- No existing conditions: 0.9%
Mortality increases dramatically when healthcare is overwhelmed
The mortality rate will also increase if hospitals and healthcare workers are overwhelmed and unable to provide care for infected people. We saw this happen in China and in Italy, and there is a looming threat that it will happen in the U.S. as well. The purpose of social isolation, social distancing, and quarantining measures is to “flatten the curve”; another way to put that would be to lessen the surge, the surge being the swarm of patients who could hit hospitals all at once. If, and more likely when, that happens, mortality rates will increase because beds will be full, there will be no more available medical professionals, supplies (like ventilators, face masks, and medicines) will run out, and healthcare professionals will have to treat people based on the best likely outcomes, as they had to in Italy (and is standard practice in crisis situations).
That means that the sickest people will die, and that will dramatically increase the mortality rate. In Italy, the mortality rate of infected people is hovering around a staggering 9 percent; that is in part due to Italy’s large elderly population, but it can also be tied to surges on hospitals and healthcare workers’ determination to focus on patients with the best chances of survival.
Surges on hospitals also result in healthcare workers contracting the disease, and then being unable to work and becoming a strain on the system; again, this has been the case in Italty and China, where the director of the Wuhan Hospital died of COVID-19 in February. As of mid-March in Switzerland, health officials estimated their health care system would be over-capacity by the end of the month.
Some projections say the U.S. healthcare system will reach capacity by the end of March. Again, to combat this, countries need to flatten the curve, and as it currently stands, in the U.S. the curve is still rising.
Sources: NCBI, Euro News, Bloomberg, University of Minnesota, Washington Post, Reuters, New York Times, Newsweek, The Economist, Centers for Disease Control and Prevention, Stat News, Daily Signal, CNN, Vox