New data suggests Canada's 'gamble' on delaying, mixing and matching COVID-19 vaccines paid off
CBC
This is an excerpt from Second Opinion, a weekly roundup of health and medical science news emailed to subscribers every Saturday morning. If you haven't subscribed yet, you can do that by clicking here.
New Canadian data suggests the bold strategy to delay and mix second doses of COVID-19 vaccines led to strong protection from infection, hospitalization and death — even against the highly contagious delta variant — that could provide lessons for the world.
Preliminary data from researchers at the British Columbia Centre for Disease Control (BCCDC) and the Quebec National Institute of Public Health (INSPQ) shows the decision to vaccinate more Canadians sooner by delaying second shots by up to four months saved lives.
The researchers excluded long-term care residents from the data, who are generally at increased risk of hospitalization and death from COVID-19, in order to get a better sense of vaccine effectiveness in the general population — and the results were exceptional.
The analysis of close to 250,000 people in B.C. from May 30 to Sept. 11 found two doses of any of the three available COVID-19 vaccines in Canada were close to 95 per cent effective against hospitalization — regardless of the approved vaccination combination.
That means for every 100 unvaccinated people severely ill in Canadian hospitals, 95 of them could have been prevented by receiving two doses of either the AstraZeneca-Oxford, Pfizer-BioNTech and Moderna vaccines, or some combination of the three.
Dr. Danuta Skowronski, a vaccine effectiveness expert and epidemiology lead at the BCCDC whose research laid the groundwork for the decision to hold back second doses based on the "fundamental principles of vaccinology," says the early data is extremely encouraging.