Age of coronavirus cases dropping in California

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.|

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 — has 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 expanded its testing 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 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.

Their parents tend to be more cautious, wearing masks and social distancing while out in public. And older people who are retired don't face workplace exposure.

Risk also may be dropping among elders, who are at higher risk of severe illness, because of increased vigilance to avoid infection.

'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' to reduce infections at these facilities, said Lemp. 'Over time, they've learned to be much more protective of nursing home and assisted living populations.'

The bump in infections among the young may also be driven, in part, by expanded testing.

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.

Younger people — who tend to have high-deductible insurance plans and no regular physician — were less likely to receive a referral for a test.

Since then, the state has launched 100 new urban community-based sites and also sends mobile sites to rural regions. In the Bay Area, new 'pop up' test sites are targeting younger populations in underserved regions, such as San Francisco's Mission District, Oakland's Fruitvale area and San Rafael's Canal District, said Rutherford. This strategy could be detecting infections in younger people who would have otherwise gone undiagnosed.

It is unknown whether the elevated rates also are influenced by the recent protests prompted by the death of George Floyd, although health experts have urged those who participated to get tested. Rutherford noted that many protesters wore masks, and there has not yet been a surge in new cases in Minnesota and Washington D.C., sites of the initial protests, despite predictions.

During the first two weeks of June, when protest-related infections would be expected to appear, 12,919 new cases were reported among young people aged 18 to 34 — up from 11,653 reported during the last two weeks of May, Lemp noted. But there's been no sharp and sudden jump that would suggest the protests triggered major contagion.

'People under age 34 are moving out and about a lot more and moving away from social distancing and consistent mask use,' said Lemp. 'That is the concern.'

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