*Correction, 3/20/2020: An earlier version of this story misstated the age range for COVID-19 deaths. The headline of this story was corrected to read "20% of COVID-19 deaths were aged 20-64 years" and the text was adjusted to reflect the correct age range.

A review of more than 4,000 U.S. patients who were diagnosed with novel coronavirus infection (COVID-19) shows that an unexpected 20% of deaths occurred among adults aged 20-64 years, and 20% of those hospitalized were aged 20-44 years.

This transmission electron microscope image shows SARS-CoV-2—also known as 2019-nCoV, the virus that causes COVID-19—isolated from a patient in the U.S. Virus particles are shown emerging from the surface of cells cultured in the lab. Courtesy NIAID-RML

The expectation has been that people over 65 are most vulnerable to COVID-19 infection, but this study indicates that, at least in the United States, a significant number of patients under 45 can land in the hospital and can even die of the disease.

To assess rates of hospitalization, admission to an ICU, and death among patients with COVID-19 by age group, the Centers for Disease Control and Prevention analyzed 4,226 COVID-19 cases in the United States that were reported between Feb. 12 and March 16.

Overall, older patients in this group were the most likely to be hospitalized, to be admitted to ICU, and to die of COVID-19. A total of 31% of the cases, 45% of hospitalizations, 53% of ICU admissions, and 80% of deaths occurred in patients aged 65 years and older. “Similar to reports from other countries, this finding suggests that the risk for serious disease and death from COVID-19 is higher in older age groups,” said the investigators. “In contrast, persons aged [19 years and younger] appear to have milder COVID-19 illness, with almost no hospitalizations or deaths reported to date in the United States in this age group.”

But compared with the under-19 group, patients aged 20-44 years appeared to be at higher risk for hospitalization and ICU admission, according to the data published March 18 in Morbidity and Mortality Weekly Report.

The researchers excluded from their analysis patients who repatriated to the United States from Wuhan, China, and from Japan, including patients repatriated from cruise ships. Data on serious underlying health conditions were not available, and many cases were missing key data, they noted.
Among 508 patients known to have been hospitalized, 9% were aged 85 years or older, 36% were aged 65-84 years, 17% were aged 55-64 years, 18% were 45-54 years, and 20% were aged 20-44 years.

Among 121 patients admitted to an ICU, 7% were aged 85 years or older, 46% were aged 65-84 years, 36% were aged 45-64 years, and 12% were aged 20-44 years. Between 11% and 31% of patients with COVID-19 aged 75-84 years were admitted to an ICU.

Of 44 deaths, more than a third occurred among adults aged 85 years and older, and 46% occurred among adults aged 65-84 years, and 20% occurred among adults aged 20-64 years.

More follow-up time is needed to determine outcomes among active cases, the researchers said. These results also might overestimate the prevalence of severe disease because the initial approach to testing for COVID-19 focused on people with more severe disease. “These preliminary data also demonstrate that severe illness leading to hospitalization, including ICU admission and death, can occur in adults of any age with COVID-19,” according to the CDC.

[email protected]

SOURCE: CDC COVID-19 Response Team. MMWR Morb Mortal Wkly Rep. 2020 Mar 18. doi: 10.15585/mmwr.mm6912e2.