How Likely Are Young People to be Hopsitalized With Coronavirus?
Let’s look at South Korea, as a baseline for a country with an outbreak of COVID-19 and extensive testing.
Korean officials said that only about 10% of coronavirus patients had cases severe enough to need hospitalization.
In China, 19% of confirmed cases were “severe” or “critical”, but this number is likely higher than the true figure, due to limited access to test kits and mild cases of COVID-19 going unreported.
In a study of 391 patients in Shenzhen, China, 0 cases of COVID-19 among those <30 years old were “severe” (in need of mechanical ventilation, in a state of septic shock or multiple organ failure, or other serious criteria) and only 1% of those aged 30-39 were severe; overall, there was an 0.6% rate of severe cases among cases younger than age 40.
The rate of contracting COVID-19 among close contacts of confirmed cases, however, was relatively constant across all age groups, running between 7 and 8%, including among children ages 0-9 years old.
In a study of 262 patients in Beijing, however, only 8% of cases younger than age 44 were “severe”, compared to 41% of cases older than age 65 and 17% of cases between age 45-64 years old.
In a study of 221 confirmed COVID-19 cases in Wuhan, 8% of patients age 44 and under were classified as “severe”, compared to 29% of cases aged 45-64 and 39% of cases over age 65.
In all three Chinese cities, this comes to a rate of 4.9% of cases in under-40 or under-45 patients being severe.
But this is probably an overestimate, since Chinese testing probably understates the number of mild cases – note that the Chinese numbers show 19% of cases being severe, while Korea, where everyone gets tested, only has 10% of cases severe.
10% of all Korean cases are severe; let’s assume this is the true severity rate, since all Korean people were tested for the disease.
Let’s assume that in China there is a bias against diagnosing mild cases; let’s assume there are m times more mild cases in reality than were picked up by the Chinese diagnostic testing, such that if you picked up all the mild cases you’d actually get the Korean estimate of 10% of cases being severe.
136/(136 + m* (874-136)) = 0.10
136 = 0.10(136+ m738)
73.8m = 122.4
m = 1.66
Ok, so let’s compute a corrected estimate for the young person’s risk, assuming that there are 1.66x as many mild cases in young people than were observed.
There were 17 severe cases observed under 44, and 332 mild cases.
The true number of mild cases in the three Chinese cities should actually be 332 * 1.66 = 551.
So the true corrected risk for getting severe disease as a young person is 17/551 = 3.1%.
Young people exposed to COVID-19 are as likely as old people to become infected and contagious. Avoiding infection is prosocial, as it prevents passing COVID-19 to more vulnerable people.
Young (<40) people who contract COVID-19 have a very low death rate, 0.1-0.2%.
Young (<40) people who contract the virus have a low (~3%) chance of having a “severe” case, requiring mechanical ventilation or other intensive care.
However, if hospital beds are unavailable, people with severe cases who don’t go to the hospital will likely die. So this 3% severe case rate translates to more like a 3% fatality rate if a young person catches the disease when hospitals are over capacity.
Whether severe or mild, a high proportion of confirmed cases of SARS had chronic psychiatric and fatigue symptoms after recovery from acute illness, and it’s possible that similar problems may arise from COVID-19.
COVID-19 can infect the cerebrospinal fluid, and a few percent of severe SARS cases had chronic neurological problems, so perhaps a similar number of severe COVID-19 cases might have chronic neurological sequelae.
Written by Sarah Constantin