VANCOUVER -- Variants of concern now make up about 60 per cent of identified COVID-19 cases across British Columbia, and even more in the health region that includes Vancouver.

Upwards of 70 per cent of infections found in the Vancouver Coastal Health region from April 4 to 10 involved variants of concern, most commonly the P.1 variant associated with Brazil, provincial health officer Dr. Bonnie Henry revealed at her monthly modelling presentation Thursday.

While officials have previously spoken about an eruption of P.1 cases in the Whistler area, Henry noted that there have been clusters in different parts of the region as well.

"We've had a number of different introductions of P.1 and transmission chains in different areas of Vancouver Coastal," she said.

Just over 60 per cent of cases identified in the neighbouring Fraser Health region last week involved variants, and the majority of those are the B.1.1.7 variant associated with the U.K.

Both variants are believed to be much easier to catch, particularly indoors, and epidemiologists have pointed to research suggesting P.1's mutations may make it more resistant to COVID-19 antibodies.

There are also concerns that some variants may cause more severe illness in younger age groups.

Data presented Thursday shows an alarming spike in hospitalizations over recent weeks involving people who are between 40 and 59. There has also been a more gradual but significant increase in hospitalizations for those 60-79.

"That why it's so important that we continue to focus our age-based immunization program on those down to age 40, in particular," Henry said.

Provincially, cases involving variants of concern are split approximately 50-50 between P.1 and B.1.1.7.

There are variant cases in every corner of B.C., Henry said, but their prevalence in some health authority regions is currently much lower. Fewer than 10 per cent of cases identified in the Northern Health region from April 4 to 10 involved variants.

Variants of concern now make up about 60 per cent of identified COVID-19 cases across British Columbia, and even more in the health region that includes Vancouver.

Upwards of 70 per cent of infections found in the Vancouver Coastal Health region from April 4 to 10 involved variants of concern, most commonly the P.1 variant associated with Brazil, provincial health officer Dr. Bonnie Henry revealed at her monthly modelling presentation Thursday.

While officials have previously spoken about an eruption of P.1 cases in the Whistler area, Henry noted that there have been clusters in different parts of the region as well.

"We've had a number of different introductions of P.1 and transmission chains in different areas of Vancouver Coastal," she said.

Just over 60 per cent of cases identified in the neighbouring Fraser Health region last week involved variants, and the majority of those are the B.1.1.7 variant associated with the U.K.

Both variants are believed to be much easier to catch, particularly indoors, and epidemiologists have pointed to research suggesting P.1's mutations may make it more resistant to COVID-19 antibodies.

There are also concerns that some variants may cause more severe illness in younger age groups.

Data presented Thursday shows an alarming spike in hospitalizations over recent weeks involving people who are between 40 and 59. There has also been a more gradual but significant increase in hospitalizations for those 60-79.

"That why it's so important that we continue to focus our age-based immunization program on those down to age 40, in particular," Henry said.

Provincially, cases involving variants of concern are split approximately 50-50 between P.1 and B.1.1.7.

There are variant cases in every corner of B.C., Henry said, but their prevalence in some health authority regions is currently much lower. Fewer than 10 per cent of cases identified in the Northern Health region from April 4 to 10 involved variants.

Officials recently revealed they would no longer routinely do whole genome sequencing to confirm all variant cases, a decision that drew some criticism.

Henry explained that they now have a screening test that can reliably detect the B.1.1.7 variant and only takes a day or two to complete, compared to the approximately one week turnaround time for genome sequencing.

"We no longer need to do whole genome sequencing for all the people who screen positive for the B.1.1.7," she said.

But because the screening tests are less reliable for other variants, Henry said B.C. will continue using sequencing to confirm cases that are flagged as variants other than B.1.1.7.

"The screening tests we have for other variants look for mutations that are common to many different variants, so you can't tell for sure if it's a P.1 or a B.1.351 just by the screening test," Henry said. "So we will continue to do whole genome sequencing on all of those so we're not missing any new variants that come up that may be important in terms of transmission in the province."

The province will also be doing sequencing on five to 10 per cent of variant cases to watch for additional mutation, the provincial health officer said.

The spread of variants has been blamed, in part, for the worsening state of the pandemic in B.C. The province's third wave has broken numerous records, including for hospitalizations and patients in intensive care.

Henry noted that rule-breaking behaviour like meeting friends indoors has become much riskier – and the chances of bringing the virus home and passing it to entire families has grown substantially.

"Before if there were 10 people in a household, we might see transmission to two or three other people at most," she said. "Now we're seeing, with the new variants in particular, that transmission can be widespread in households. It may be that the whole household becomes infected."

British Columbia has been under several strict COVID-19 restrictions since November, and more were introduced in late March barring indoor dining at restaurants and indoor group fitness activities. It's unclear how long those might remain in place, but it's expected that at least some of them will continue past the end date of April 19 that was initially suggested.

While people are allowed to gather outdoors in groups of 10, Henry urged the public to consider spending more time with their own household and stressed the need to be safe even when seeing others outside.

"There's no zero risk right now," she said. "Keep your distance. If you're going to be in close contact, wear masks, even if it's outside."

The spread of variants has been blamed, in part, for the worsening state of the pandemic in B.C. The province's third wave has broken numerous records, including for hospitalizations and patients in intensive care.

Henry noted that rule-breaking behaviour like meeting friends indoors has become much riskier – and the chances of bringing the virus home and passing it to entire families has grown substantially.

"Before if there were 10 people in a household, we might see transmission to two or three other people at most," she said. "Now we're seeing, with the new variants in particular, that transmission can be widespread in households. It may be that the whole household becomes infected."

British Columbia has been under several strict COVID-19 restrictions since November, and more were introduced in late March barring indoor dining at restaurants and indoor group fitness activities. It's unclear how long those might remain in place, but it's expected that at least some of them will continue past the end date of April 19 that was initially suggested.

While people are allowed to gather outdoors in groups of 10, Henry urged the public to consider spending more time with their own household and stressed the need to be safe even when seeing others outside.

"There's no zero risk right now," she said. "Keep your distance. If you're going to be in close contact, wear masks, even if it's outside."