Younger Adults Made Up Greatest Rate of New US COVID-19 Cases over Summer

The age distribution of the coronavirus 2019 (COVID-19) pandemic has shifted in the US over recent months, according to new data. The median patient age is getting younger.

In new research published to the US Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR), a team of investigators from the CDC COVID-19 Response Team found that virus incidence was actually greatest among the 20-29 year-old population in the US from June-August of this year.

After being only the fourth most commonly infected decade-length age group in May, 20-29 year-olds accounted for more than 20% of all new national cases in every month of this summer.

Investigators, led by Tegan K. Boehmer, PhD, noted a similar shift in median COVID-19 age in Europe during the same months, and correlating increased incidence of COVID-19 related emergency department (ED) visits as well as positive SARS-CoV-2 RT-PCR test results in the younger age group.

What’s more, in southern regions where greater outbreaks were observed in those months, investigators observed a preceding of positive SARS-CoV-2 test results among adults aged 20-39 years old to increases among adults aged at least 60 years old by about 4-15 days—or, the mean time to transmission. Boehmer and colleagues believe the younger adult population—who have been observed to more commonly have mild to no symptoms of COVID-19—may have been unwittingly contributory to greater virus risks in older populations at the observed time.

The findings also highlight the issue of an unevenly reopened workforce in the US: the average “essential workers” who resumed or continued work with little to no offerings of enhanced protection from the virus are generally younger. The very same people may be more likely to visit an indoor bar or restaurant, join a large gathering of friends, or participate in other high transmission-risk activities.

In an interview with Contagion® regarding the findings, Boehmer highlighted a trio of categorical implications based on the understanding that the median COVID-19 patient age is dropping:

• Work expectations and social behaviors vary among age groups.
• Younger adults are indeed more likely to have mild to no symptoms from COVID19.
• More young people are at risk than they’re willing to understand.

“This is not a benign disease in younger adults,” Boehmer said. “Young adults who have underlying conditions such as obesity, diabetes, or hypertension can get seriously ill from COVID-19.”

Investigators advocated for greater emphasis on targeted strategies that mitigate infection and transmission risks among younger adults, including age-targeting prevention messaging and greater restriction on in-person gatherings and events.

“Given the role of asymptomatic and presymptomatic transmission all persons, including young adults, should take extra precautions to avoid transmission to family and community members who are older or who have underlying medical conditions,” they concluded.