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It's not over. Experts warn of new COVID wave

A variant and fading vaccine protection could bring a rise in cases in April.
While B.C. will likely see short-term stability in case levels, the modelling group warns  waning immunity from booster doses could see the BA.2 sub-variant fuel another Omicron wave nearing 1,500 daily reported cases by the end of  April. 

As British Columbia ends mask mandates and other pandemic measures, an independent group of experts warned Thursday the province could face a  second, smaller Omicron wave within months.

The BC COVID-19 Modelling Group,  composed of independent experts and academics, urged the government to  authorize fourth vaccine doses for high-risk people and improve  ventilation for essential services to blunt a potential sixth wave  fuelled by the even more transmissible BA.2 sub-variant.

“With Canada having moved away from mask  requirements and other mandated safety measures, there is a need to  create safer indoor spaces, especially for those at higher risk,” the  group’s report said.

COVID-19 cases among those 70-plus have  dropped to less than a fifth of the peak of Omicron in January,  according to the new report.

The drop in cases has been  even more pronounced among younger age groups, but is difficult to  quantify because most under 70 are no longer eligible for PCR testing.

But while B.C. will likely  see short-term stability in case levels, the modelling group warns  waning immunity from booster doses could see the BA.2 sub-variant fuel  another Omicron wave nearing 1,500 daily reported cases by the end of  April. 

Omicron’s crest saw 4,078 daily cases reported on Dec. 31.

“The COVID-19 trajectory in B.C. over the  next month depends strongly on how fast waning occurs and whether people  continue to abide by safety measures, even if they are no longer  required,” the report said.

Provincial health officer Dr. Bonnie Henry  said last week that B.C. remains vulnerable to future variants that may  transmit more easily or evade protection afforded by vaccines.

“Those are the things that we don’t yet know,” she said as she announced the end of the mask mandate March 10. 

More than half of cases are now caused by  the BA.2 sub-variant of Omicron, whose share of daily cases rose  steadily through February and has now stabilized, Canada-wide data  shows. 

The risks of another wave are mitigated by  the immunity British Columbians have from vaccination or previous  infection, Henry and the group agree.

But they remain a concern for people who  are considered high risk, including those over 70 and who are  immunocompromised. The vast majority of high-risk and older people  received their boosters before Dec. 31, almost three months ago.

According to reports  from the United Kingdom and B.C.’s own figures, people who are  unvaccinated are 10 times more likely to be hospitalized as a result of  Omicron than those who are vaccinated.

But three to four months after a booster shot, that protection is cut in half.

Booster efficacy against infection from Omicron also drops sharply in the same timeframe.

“Many people in B.C., especially those most  susceptible to severe health impacts of COVID-19, received boosters  more than three months ago and are now experiencing declining levels of  protection,” said the report.

The group recommended B.C. follow advice  from Canada’s National Advisory Committee on Immunization to authorize a  fourth dose for immunocompromised individuals three months after their  third dose. 

“The option of a fourth dose, 3 to 4 months  following a third booster dose, would reduce hospitalization risks for  those most susceptible to severe COVID-19 reaction,” the report said.

Ultimately, the group warned, the impacts  of the BA.2 sub-variant will be determined by how many people continue  to mask, limit gatherings and how quickly booster immunity wanes or is  bolstered by fourth doses.

“While the COVID-19 situation is good and improving, B.C. faces a number of short-term risks,” the report said. 

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