The Centers for Disease Control (CDC) just released some of the early data on severe outcomes, including hospitalizations and fatalities, for the first 4,226 COVID-19 patients in the US. Health officials have been relying primarily on data from other countries like China and Italy, whose populations and healthcare systems are not necessarily comparable to our own. Though this continues to be an evolving situation, this early research is telling. It supports something we know, and raises a red flag on something that needs more attention.
Case fatality rates
Forty-four COVID-19 cases with known status had died as of March 16, 2020. That represents approximately 1% (1 in 100) of identified cases. (I will address whether this is a true representation of case fatality rate later on). Cases 85 years-old and above had the highest fatality rates, ranging from 10% of all cases in that age group, up to 27% of those hospitalized (Table). Among cases 65-85, 3-11% had died. The case fatality rate among those ages 20-54 was less than 1%. This is in line with what we have learned and heard previously about COVID-19 – that older individuals are heightened risk of dying. What we learned next was somewhat more surprising.
Case Hospitalization rates
Among the 12% of cases (508) with a known hospitalization, we again saw that the highest number of patients, 35%, were cases over the age of 65. However, we also saw that younger patients, between the ages of 20 and 54, made up 38% of all hospitalizations. This suggests that although the risk of death is lower for younger individuals, they are still at risk of severe disease that requires hospitalization. This is important because it addresses a dangerous misconception that young, healthy people are not at risk of serious illness from COVID-19, which has been a detriment to social distancing measures enacted to slow the spread of the virus.
what does this all mean?
This are very early data based on what will amount to be a very small number of the cases we see in this country. The analysis was limited to the 2,449 cases whose age was known. Further, these data are still incomplete. Most cases are still unresolved. Some may still be hospitalized or yet-to-be hospitalized. Some may die. Most will recover. The report also did not include information about underlying health conditions, which we know also increase the risk of death.
When it comes to case fatality rate, we are not yet seeing the full picture. These initial cases came before widespread testing was made available in the US. In other words, these cases likely came to our attention due to illness or because they were exposure to an already confirmed case. Some evidence suggests that for for every confirmed case, there are 7 more that have yet-to-be identified.
The number of identified cases will continue to rise in the US, and with that increase in cases, the true case fatality rate will surface. If China is any indication, we can anticipate it to be closer to 0.1% (1 in 1000) or less.
Table: COVID-19 severe outcomes by age – United States, february 12-march 16, 2020
| Age group (cases) | Hospitalization | ICU admission | Fatality |
| 0–19 (123) | 1.6–2.5 | 0 | 0 |
| 20–44 (705) | 14.3–20.8 | 2.0–4.2 | 0.1–0.2 |
| 45–54 (429) | 21.2–28.3 | 5.4–10.4 | 0.5–0.8 |
| 55–64 (429) | 20.5–30.1 | 4.7–11.2 | 1.4–2.6 |
| 65–74 (409) | 28.6–43.5 | 8.1–18.8 | 2.7–4.9 |
| 75–84 (210) | 30.5–58.7 | 10.5–31.0 | 4.3–10.5 |
| ≥85 (144) | 31.3–70.3 | 6.3–29.0 | 10.4–27.3 |
| Total (2,449) | 20.7–31.4 | 4.9–11.5 | 1.8–3.4 |
Lower bound of range = percentage among total in age group; Upper bound of range = percentage among total in age group with known hospitalization status, ICU admission status, or death; Table adapted from CDC.