California’s COVID-19 cases are getting younger

As California’s economy opens up, coronavirus cases are getting younger and younger.

An analysis released this week reveals that more than 44% of new diagnoses are in people age 34 or younger, up from 29% a month ago.

There’s a corresponding drop in cases among older people. The proportion of COVID-19 cases among Californians older than 50 has plummeted from 46% to 30.5% in the past month.

The proportion of cases among middle-aged Californians – ages 35 to 49 – have plateaued, neither rising nor falling.

“It is striking that there is such a strong shift. Cases are much younger now than they were earlier in the pandemic,” said infectious disease epidemiologist George Lemp, who calculated the trends using historical data from the California Department of Public Health.

“It may reflect the opening up of California since mid-May, particularly among younger people who may have started to move away from the practices of social distancing and consistent mask use,” he said.

It’s unknown whether the shift is in part due to the increased availability of tests to everyone who wants one. California has significantly ramped up esting capacity – scaling up from just 2,000 per day in April to more than 60,000 tests per day this week.

The state does not report overall trends in COVID-19 cases, by age. But Lemp recorded and archived the data from three different snapshots in time to detect the dramatic shift.

People between ages of 18 to 34 now claim the largest share of new infections in the state, with 12,919 known cases diagnosed between May 31 to June 13. The second largest group, with 9,691 new cases, are people between the ages of 35 and 49.

There has been a worrisome jump in youth under the age of 17. From the beginning of the pandemic until May 13, cases were rare, with a cumulative tally of only 2,799 diagnoses reported in this group. But that number was surpassed in merely two weeks, between May 14 and May 30, with 3,455 new cases. And it was exceeded again, between May 31 and June 13, with 3,930 new cases.

“It’s likely a combination of factors,” said Lemp. “Young parents with young kids who are moving away from mitigation measures — and teenagers hanging out together.”

While there’s a common misperception that only the old and frail can contract the virus, the analysis is a reminder that California’s youth also are vulnerable. But COVID-19 is less deadly in the young.

The trend helps explain why the state isn’t seeing a spike in hospital visits and deaths from the disease – even as counties reopen and cases are gradually rising, said Lemp, former director of the University of California’s HIV/AIDS Research Program.

“Death rates and hospitalization go up dramatically with older age,” he said.

Surveys show that there’s a generation gap in attitudes toward mask-wearing. Youth are less likely to wear a facial covering, and hang out in closely packed groups totally free of social distancing. Young men, in particular, view mask-wearing as “not cool” and a sign of weakness.

“A lot of people have gotten the message about protective masking. But as I walk around my neighborhood, I don’t see masks on teenagers,” said UC San Francisco epidemiologist Dr. George Rutherford.

Older people are more likely to be retired, so they don’t face workplace exposure.

Risk also may be dropping among elders because they are taking steps to avoid infection. People over 65 are at increased risk from illness due to underlying health problems, such as heart disease, lung disease or diabetes.

“Early on, there were a lot of unfortunate mistakes made at nursing homes, either because we didn’t know enough or people didn’t move quickly enough,” said Lemp of the high rates of infections among residents and staff in long-term care facilities. “Over time, they’ve learned to be much more protective of nursing home and assisted living populations.”

But the shift may also be driven, in part, by expanded testing.  The number of tests increased by 166% between May 13 and June 13, when diagnoses among youth people soared.

When the virus was first circulating in our region, and tests were in short supply, older and high-risk people were most likely to be tested. Test sites were located in more affluent communities, or required a car, according to Dr. Georges Benjamin, executive director of the American Public Health Association.