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Coronavirus (COVID-19) Mortality Rate

Last updated: May 14, 22:00 GMT

See also: Death Rate by Age and Sex of COVID-19 patients


When calculating the mortality rate, we need:

  1. The number of actual cases. We need to know the number of actual cases (not merely the reported ones, which are typically only a small portion of the actual ones) that have already had an outcome (positive or negative: recovery or death), not the current cases that still have to resolve (the case sample shall contain zero active cases and include only “closed” cases).
  2. The number of actual deaths related to the closed cases examined above.

Considering that a large number of cases are asymptomatic (or present with very mild symptoms) and that testing has not been performed on the entire population, only a fraction of the SARS-CoV-2 infected population is detected, confirmed through a laboratory test, and officially reported as a COVID-19 case. The number of actual cases is therefore estimated to be at several multiples above the number of reported cases. The number of deaths also tends to be underestimated, as some patients are not hospitalized and not tested.

If we base our calculation (deaths / cases) on the number of reported cases (rather than on the actual ones), we will greatly overestimate the fatality rate.

Fatality Rate based on New York City Actual Cases and Deaths

Worldometer has analyzed the data provided by New York City, the New York State antibody study, and the excess deaths analysis by the CDC. Combining these 3 sources together we can derive the most accurate estimate to date on the mortality rate for COVID-19, as well as the mortality rate by age group and underlying condition. These findings can be valid for New York City and not necessarily for other places (suburban or rural areas, other countries, etc.), but they represent the best estimates to date given the co-occurrence of these 3 studies.

Actual Cases (1.7 million: 10 times the number of confirmed cases)

New York State conducted an antibody testing study [source], showing that 12.3% of the population in the state had COVID-19 antibodies as of May 1, 2020. The survey developed a baseline infection rate by testing 15,103 people at grocery stores and community centers across the state over the preceding two weeks. The study provides a breakdown by county, race (White 7%, Asian 11.1%, multi/none/other 14.4%, Black 17.4%, Latino/Hispanic 25.4%), and age, among other variables. 19.9% of the population of New York City had COVID-19 antibodies. With a population of 8,398,748 people in NYC [source], this percentage would indicate that 1,671,351 people had been infected with SARS-CoV-2 and had recovered as of May 1 in New York City. The number of confirmed cases reported as of May 1 by New York City was 166,883 [source], more than 10 times less.

Actual Deaths (23,000: almost twice the number of confirmed deaths)

As of May 1, New York City reported 13,156 confirmed deaths and 5,126 probable deaths (deaths with COVID-19 on the death certificate but no laboratory test performed), for a total of 18,282 deaths [source]. The CDC on May 11 released its “Preliminary Estimate of Excess Mortality During the COVID-19 Outbreak — New York City, March 11–May 2, 2020” [source] in which it calculated an estimate of actual COVID-19 deaths in NYC by analyzing the “excess deaths” (defined as “the number of deaths above expected seasonal baseline levels, regardless of the reported cause of death”) and found that, in addition to the confirmed and probable deaths reported by the city, there were an estimated 5,293 more deaths to be attributed. After adjusting for the previous day (May 1), we get 5,148 additional deaths, for a total of actual deaths of 13,156 confirmed + 5,126 probable + 5,148 additional excess deaths calculated by CDC = 23,430 actual COVID-19 deaths as of May 1, 2020 in New York City.

Infection Fatality Rate (23k / 1.7M = 1.4% IFR)

Actual Cases with an outcome as of May 1 = estimated actual recovered (1,671,351) + estimated actual deaths (23,430) = 1,694,781.

Infection Fatality Rate (IFR) = Deaths / Cases = 23,430 / 1,694,781 = 1.4% (1.4% of people infected with SARS-CoV-2 have a fatal outcome, while 98.6% recover).

Mortality Rate (23k / 8.4M = 0.28% CMR to date) and Probability of Dying

As of May 1, 23,430 people are estimated to have died out of a total population of 8,398,748 in New York City. This corresponds to a 0.28% crude mortality rate to date, or 279 deaths per 100,000 population, or 1 death every 358 people. Note that the Crude Mortality Rate will continue to increase as more infections and deaths occur (see notes under the paragraph “Herd Immunity” below for details).

Mortality Rate by Age

See also: Death Rate by Age and Sex of COVID-19 patients

When analyzing the breakdown of deaths by age and condition [source], we can observe how, out of 15,230 confirmed deaths in New York City up to May 12, only 690 (4.5% of all deaths) occurred in patients under the age of 65 who did not have an underlying medical condition (or for which it is unknown whether they had or did not have an underlying condition).

Underlying illnesses include Diabetes, Lung Disease, Cancer, Immunodeficiency, Heart Disease, Hypertension, Asthma, Kidney Disease, GI/Liver Disease, and Obesity [source]

Under 65-year-old (0.09% CMR to date)

85.9% of the population (7,214,525 people out of 8,398,748) in New York City is under 65 years old according to the US Census Bureau, which indicates the percent of persons 65 years old and over in New York City as being 14.1% [source].

We don’t know what percentage of the population in this age group has an underlying condition, so at this time we are not able to accurately estimate the fatality rate for the under 65 years old and healthy.

But we can calculate it for the entire population under 65 years old (both healthy and unhealthy): with 6,188 deaths (26% of the total deaths in all age groups) occurring in this age group, of which 5,498 deaths (89%) in patients with a known underlying condition, the crude mortality rate to date will correspond to 6,188 / 7,214,525 = 0.09% CMR, or 86 deaths per 100,000 population (compared to 0.28% and 279 deaths per 100,000 for the general population).

So far there has been 1 death every 1,166 people under 65 years old (compared to 1 death every 358 people in the general population). And 89% of the times, the person who died had one or more underlying medical conditions.

NOTE: We are gathering and analyzing additional data in order to provide more estimates by age group.

Herd Immunity and final Crude Mortality Rate

Crude mortality rate is not really applicable during an ongoing epidemic.

And to reach herd immunity for COVID-19 and effectively end the epidemic, approximately two thirds (67%) of the population would need to be infected. As of May 1, New York City is at 20%, based on the antibody study findings.

Therefore, the crude mortality rate has the potential to more than triple from our current estimate, reaching close to 1,000 deaths per 100,000 population (1% CMR), and close to 300 per 100,000 (0.3% CMR) in the population under 65 years old, with 89% of these deaths (267 out of 300) occurring in people with a known underlying medical condition (including obesity).

Historical Account of the Initial Estimates


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