More countries investigating delaying second doses of COVID-19 vaccine


An increasing number of health officials in countries around the world are thinking about the idea of giving as many people as possible a first dose of a COVID-19 vaccine -- not two doses about three weeks apart.

Canada is one of the countries looking at how long someone could go without getting a second dose.

Dr. Theresa Tam, Canada's chief public health officer, says she has asked the National Advisory Committee on Immunization to investigate.

Several countries are now investigating or authorizing the delay of those second doses, to get more people vaccinated with first doses.

Denmark authorized a six-week delay.

The UK is pushing that second dose back by 12 weeks for its two approved vaccines from Pfizer-BioNTech and AstraZeneca.

Germany is also investigating whether to delay the second dose.

Pfizer told The Canadian Press in a statement it doesn't endorse a delayed-dose plan.    

Moderna similarly says it can't comment on whether its vaccine is effective outside the two-dose, 28-day schedule.