COVID19 Fatality Rates
According to various unofficial Covid19 trackers that calculate the death rate by dividing total deaths by the number of known cases, about 6.4 percent of people infected with the virus have now died worldwide. The death rate in the United States is currently 4.3% compared to 2% in South Korea and 13% in Italy. Italy’s high death rate may be attributed to having the second oldest population in the world.
Fatality rates calculated by comparing deaths, which are relatively easy to count, to infections, which are not, almost certainly overestimate the true lethality of the virus. The total number of cases most commonly includes those people whose symptoms were severe enough to be tested. This definition results in a severity bias. Epidemiologists estimate there are at least 5 to 10 times more people with asymptomatic infections than confirmed cases.
Even the death rate is often inaccurate at the time of calculation because deaths typically occur about one month are a person becomes infected. Also, not all deaths are apparent at the same time. COVID19 deaths that occur at home are underreported compared to those that occur in a hospital.
All 3,711 passengers and crew members aboard the Diamond Princess cruise ship were tested and 19% were positive. The case fatality rate, which included symptomatic individuals, was 2.6%. However, 46% of the passengers who tested positive were asymptomatic at the time of testing. The infection fatality rate, which included both symptomatic and asymptomatic individuals who tested positive, was 1.3%. Many other studies have also found that approximately 40% of individuals testing positive are asymptomatic. One of the most complete studies occurred in Iceland where 6% of its entire population was tested. Forty three percent of those who tested positive were asymptomatic at the time of testing.
The infection fatality rate in the general population may prove to be less than 1%. Even at this rate, COVID19 still remains a serious public health threat. The infection fatality rate of seasonal influenza is approximately 0.1%, but it kills tens of thousands of Americans each year.
References
Harmon, A. Why we don’t know the true death rate for COVID-19. New York Times, April 17, 2020.
Verity R et al. Estimates of the severity of coronavirus disease 2019: a model-based analysis. Lancet, published online March 30, 2020 https://doi.org/10.1016/S1473-3099(20)30243-7
