Omicron could boost waning immunity, blood tests show

Immunity against COVID-19 among vaccinated adult Canadians and those who have already contracted the virus has been waning throughout the population, tests on donated blood have found.

Tests on around 9,000 donated blood samples from across Canada show that antibodies in the blood which fight the virus declined in October among all age groups, with experts saying the waning immunity is likely to have continued in November and December.

But the head of the government's COVID-19 Immunity Task Force says that the highly contagious Omicron variant may offer an "immune dividend" offering fresh protection against future infection.

Scientists on the task force are now analyzing the extent of immunity offered by Omicron, as well as "memory of immune protection" in the cells which can kick in with future COVID-19 infections.

With the task force studies of immunity levels informing government policy on booster shots, the findings are likely to influence when and how many booster shots people may have in future.