Manitoba logged largest post-holiday infection spike: blood analysis

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This article was published 11/03/2022 (1483 days ago), so information in it may no longer be current.

A new analysis of COVID-19 antibodies among blood donors shows Manitoba recorded the largest spike in infections of all provinces outside Quebec following the arrival of the Omicron variant.

Results from a recent seroprevalence study conducted by the COVID-19 immunity task force show infection-acquired antibody levels nearly doubled in Manitoba between December 2021 and January 2022, from 8.18 per cent to 15.85 per cent.

According to the report, the jump was the highest among Canadian Blood Services donors from nine provinces. Data from Quebec was not included in the comparative analysis.

Manitoba also posted the highest infection-acquired seropositivity level in January among nine provinces.

“You had Omicron circulating really well when it was highly transmissible and that’s why you ended up having this percentage of blood donors showing evidence of having been infected,” Dr. Catherine Hankins, task force co-chairwoman, said in an interview Friday.

On average, infection-acquired antibodies climbed from 7.5 per cent to 10.1 per cent between Dec. 25, 2021, and Jan. 15, among donors from all provinces. It takes one to two weeks before antibodies are detected, meaning infections captured in the study occurred up to the 2021 holiday period, the report noted.

During that period, Manitoba’s public health capacity was overrun with demand for COVID-19 tests, as tens of thousands of people caught the Omicron variant.

Public health orders restricted private gathering sizes but continued to allow most businesses, including restaurants and other public venues, to operate at half-capacity and with limits on alcohol service. Meantime, essential service providers, including the Winnipeg Police Service, personal care homes, hospitals, public transit, corrections, and emergency responders, were stretched thin as workers fell ill in quick succession.

Hankins said it’s difficult to explain why Manitoba had a pronounced spike in infection levels compared to other western provinces, including Saskatchewan and Alberta, which logged infection-acquired seropositivity levels of 13.46 per cent and 13.99 per cent, respectively.

“This is a window on what was happening in the general population,” she said. “It’s hard to know. Did you really party harder over Christmas?”

However, the rollout of second doses of the COVID-19 vaccine, the availability of booster shots, plus the implementation and adherence to public health measures, all likely influenced the higher infection level among Manitoba donors, Hankins said.

“I think what’s striking is we’re talking about the Prairie provinces,” said Hankins, a professor at McGill University in the school of population and global health. “Alberta, Saskatchewan, Manitoba are consistently higher than Ontario.”

A federal analysis of public health measures in mid-December indicated Manitoba had the most stringent approach of the 10 provinces, but by early January, it had fallen to the middle of the pack as other jurisdictions tightened restrictions.

However, Manitoba’s measures were tighter than Alberta and Saskatchewan until mid-February, according to the Bank of Canada’s COVID‑19 stringency index.

The prevalence of COVID-19 in the community noted by the task force’s study reinforces the importance of public health recommendations as orders are lifted, Hankins said.

“The vaccines are holding and are important, but also are our non-pharmaceutical measures like putting on a mask in a crowded setting,” Hankins said. “Just lifting mask mandates and vaccine mandates and so on, doesn’t mean that it’s now a free for all.

“The virus is still here so we have to use some judgement. You do not want to get this infection if you can avoid it.”

danielle.dasilva@freepress.mb.ca