No evidence surgical masks protect against flu: health agency

There is no evidence inexpensive surgical masks can protect against flu virus particles small enough to be inhaled into the lower respiratory tract or the lungs, says anew report written for the Public Health Agency of Canada.

And the report, released Wednesday, says it's unclear how effective surgical masks are in blocking flu virus particles that are bigger and therefore likely to settle in the nose and throat of an exposed person.

The report is meant to serve as guidance to the Public Health Agency on the question of how flu is transmitted and how best to protect against infection.

Federal, provincial and territorial health authorities need that kind of information to decide what kind of masks to stockpile to protect health-care workers during a flu pandemic cheap surgical masks or more expensive N95 respirators.

The report, produced by the Council of Canadian Academies, represents the findings of a 13-member panel of experts chaired by Dr. Donald Low, microbiologist-in-chief at Mount Sinai Hospital in Toronto.

The panel says the scientific evidence remains unclear about how precisely flu is spread and what role exposure to bigger or smaller virus particles plays in transmission.

It concludes flu viruses are mainly transmitted over short distances and that more people become infected by inhaling viruses than by touching contaminated surfaces.