Canada’s top doctor says the science behind B.C.’s decision to extend the gap between COVID-19 vaccine doses from 21 days to four months could be promising.
However, the National Advisory Committee on Immunization is still reviewing the data around the delay.
On Monday, B.C. provincial health officials decided to spread the doses of the Moderna and Pfizer vaccines to 16 weeks.
Originally, the doses to combat COVID-19 were spread out by 28 days. That was then pushed to 42 days and now it is 112 days.
The goal is to get more people vaccinated with the first dose before people are fully vaccinated with both doses.
“There will be a continuous monitoring of the vaccine effectiveness as we go along,” Dr. Theresa Tam, Canada’s Chief Public Health Officer said Tuesday. “Not just globally but British Columbia and Quebec, for instance, (they) have already stretched the interval of the administration between the two doses, giving us domestic real-life data from long-term care and from health-care workers.”
However, Dr. Mona Nemer, Canada’s Chief Science Advisor, said not all viruses act the same way and therefore, not all vaccines act the same way.
“I’ve said it before, this is the first time that we have RNA vaccines. We don’t know how our bodies respond to them. We don’t know how strong immunity is and how long it lasts.”
“So I think we need to maintain some humility in the face of this evolving science and to maintain public trust, that we be open and transparent about the data that is being used for decision-making,” Nemer added.
The National Advisory Committee on Immunizations is looking at the evidence to support the time span between the doses and is expected to release its findings later this week.
B.C.’s Provincial Health Officer said Tuesday that efficacy studies of the vaccine have shown that receiving a first dose of the vaccine is over 90 per cent effective for at least a few months.
“That is why I am so confident that the decision we made, over this weekend, to extend that interval is the best one based on all of the science and the data that we have to maximize the benefit to everybody in our community here in B.C.,” Henry said.
She added the more people who have received one dose of the vaccine lowers the risk of passing the virus on to others.
Henry said the hope is that some of the restrictions can be lifted once enough people have received the first dose.
B.C. is expecting all adults in the province will have the option to receive their first dose before the end of July.
Pfizer, one of the vaccine manufacturers, has recommended a 21-day gap between doses and the province previously was spacing them out by 42 days.
“The extension of dose two will make a big difference in our ability to vaccinate our mass population,” Dr. Penny Ballem, who is leading the province’s vaccination plan, said Monday.