Here's what we know today, or rather, here's what the U.S. Centers for Disease Control and Prevention (CDC) knows today about how deadly the COVID-19 coronavirus infections are:
These figures are the CDC's best estimates as of 20 May 2020, which specifically apply for those who have developed COVID-19 symptoms, which according to the CDC as of 13 May 2020, can include the following:
- Fever or chills
- Shortness of breath or difficulty breathing
- Muscle or body aches
- New loss of taste or smell
- Sore throat
- Congestion or running nose
- Nausea or vomiting
After being exposed to a sufficient amount of the SARS-CoV-2 coronavirus to become infected, early studies have indicated COVID-19 symptoms can take anywhere from 4.5 to 5.8 days to develop, with a median incubation period of 5.1 days. According to the CDC, about 35% of those who become infected may never develop any of the listed symptoms associated with COVID-19. The coronavirus infection does not appear to be deadly for those who do not develop symptoms.
After the onset of symptoms, another early study found the typical period before death might occur could range between 15 and 22 days, with a median period of 18.5 days. Combined, that gives an estimated period from infectious exposure to death of anywhere from 20 to 28 days, with a median period of about 25 days. The incidence of death from COVID-19 increases with age, though most who have succumbed to it have also had underlying medical conditions, which may be more strongly correlated with an increased risk of death than age alone.
If the indicated percentages in the chart seem lower than what you may have expected, that is because the analyses on which the CDC is relying to produce these estimates is considering its spread among the whole population. Many of the deaths that have driven news headlines have occurred within especially vulnerable subsets of the population, such as among elderly Americans who reside in nursing homes or other long term care facilities, for whom coronavirus infections combined with the health conditions that led them to live in such facilities in the first place greatly increases their risk of death far above what would apply for the general population.
Compared to seasonal influenza, such as experienced during the 2018-2019 flu season, COVID-19 is about four times as deadly overall. While it is not anywhere as apparently deadly as previously thought, the available evidence indicates the SARS-CoV-2 coronavirus is still more deadly than a typical flu virus.