Mixing brands of mRNA vaccine is safe, Windsor-Essex top doctor says

Health care workers administer the COVID-19 vaccine at clinics across Simcoe Muskoka. (CTV News Barrie)

Windsor, Ont. -

The Windsor-Essex Medical Officer of Health maintains mixing mRNA vaccination brands is a “safe and effective practice.”

Dr. Wajid Ahmed issued a statement Wednesday offering clarification surrounding remarks made by World Health Organization (WHO) chief scientist Dr. Soumya Swaminathan regarding mixing COVID-19 doses.

“The comments made by WHO’s chief scientist Soumya Swaminathan was in response to individuals making their own decisions to access 3rd or 4th doses of COVID vaccines on their own instead of following public health recommendations,” Dr. Ahmed said. “The Windsor-Essex County Health Unit continues to follow the advice of Canada’s National Advisory Committee on Immunization (NACI) which recommends that the mixing of mRNA vaccines is a safe and effective practice.”

While discussing booster doses of the COVID-19 vaccine during an online briefing Monday, Dr. Swaminathan said that she advised against people mixing and matching vaccines from different manufacturers.

“It's a little bit of a dangerous trend here. We are in a data-free, evidence-free zone as far as mix and match," Dr. Swaminathan said. "It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose.”

Dr. Swaminathan issued a tweet following the briefing stating "individuals should not decide for themselves" to mix vaccine doses, but that "public health agencies can, based on available data."

Dr. Ahmed says mixing brands of the same vaccine helps more residents to receive their second dose sooner, “providing the protection necessary to prevent transmission of the Delta Variant which is now the dominant strain in Ontario.”

“The health and safety of all residents remains our top priority and the Windsor-Essex County Health Unit will continue to make recommendations based on scientific evidence and will always act in the best interest of the community.”

- With files from CTV Toronto