VANCOUVER -- During her update on B.C.'s response to COVID-19 on Thursday, provincial health officer Dr. Bonnie Henry described a recent increase in infections among residents under age 40 as "concerning."

Her concerns, she said, are based not only on the possibility that younger people could transmit the coronavirus to older, more vulnerable members of society, but also on recent research that has shown larger numbers of young people becoming seriously ill when they contract COVID-19.

"Over the past couple of months in particular, we have seen increased in COVID cases that are variants of concern," Henry said, adding B.C. has mostly seen cases of the B.1.1.7 variant, which has higher transmissibility.

"We've now seen data particularly from the U.K. but some other countries as well that shows that it can have increased severity of illness in younger people and across the age spectrum, but in younger people as well," she said. "So we are concerned about that."

While it doesn't draw an explicit connection to variants of concern, local data tells a similar story about increasing severity of illness among those in their 30s.

The B.C. Centre for Disease Control's weekly "situation reports" have shown marked increases in hospitalizations and deaths among B.C. residents ages 30 to 39 so far in 2021.

At the start of the year, as of the week that ended Jan. 9, there had been a total of 285 people in the 30-39 age group hospitalized with COVID-19 since the start of the pandemic. Sixty-two in the age group had been admitted to intensive care units, and four had died. 

Roughly a month later, as of the week that ended Feb. 6, there had been 343 hospitalizations (an increase of 20 per cent) and 68 ICU admissions. The number of deaths was unchanged at four. 

In the most recent report, which was released on March 24 and covers the week that ended March 13, hospitalizations were up to 418 (an increase of 22 per cent from Feb. 6 and 47 per cent from Jan. 9). ICU admissions were up to 78 and the number of deaths had more than doubled, to 11. 

While that's only a small fraction of the 1,411 COVID-19-related deaths that had occurred in B.C. up to that point, it's a significant increase in deaths among people under 40 in a short period of time.

From the start of the pandemic to Feb. 6, 2021, only four people under age 40 had died from COVID-19 in B.C. In the five weeks after that, seven more died. Put another way, 63 per cent of all 30-39-year-olds who have died from COVID-19 in B.C. have died in the last two months.

The under-40 data is one example of a broader trend in B.C., which has seen a significant decrease in severe illness and death from COVID-19 among older residents as vaccination has been rolled out to care homes and older members of the general public.

Last weekend, just two of 16 people who died from the coronavirus were care home residents.

Likewise, according to the latest BCCDC situation report, the median age of death from COVID-19 in the province was 70 years old during the week of March 7 to 13, down from 87 during the week of Jan. 17 to 23.

Half of the deaths recorded in the most recent report were among people under age 70, compared to just 10 per cent of deaths during the week of Jan. 24 to 30.