H1N1 flu virus Microphoto from the CDC

Here’s a fact: all influenza, not just H1N1, is mostly transmitted by breathing particles of the virus from those with the disease.

So obviously it makes sense that caregivers – from medics on the street, to hospital staff and nursing home workers – wear masks to protect themselves while working with patients with H1N1.

Last month, a panel from the Institute of Medicine of the National Academies reported that the more expensive N95 mask was far more protective than the  traditional disposable surgical-type mask because it stops smaller particles.

The panel and other health researchers in the Centers for Disease Control said the N95 was a vital defense in protecting health care workers from the H1N1 pandemic.

I got several emails on the story I posted on the panel’s conclusions. Half challenged the effectiveness of the N95.

Looks like they might be correct.

Researchers in Canada got 446 nurses in emergency departments, medical  and pediatric units in eight large Ontario hospitals to test the effectiveness of surgical masks with the N95 in protecting against influenza.

The outcome was that there was virtually no difference between masks, according to the study published in the Journal of the American Medical Association.

Of the test participants, Influenza infection occurred in 50 nurses wearing the old style surgical masks and in 48 of the nurses using the much-recommended N95 mask.

These Influenza infections were confirmed by laboratory tests

An editorial which accompanied the study said that it was a  “sad commentary” on the state of research in this area that the Canadian effort is the first and only published randomized trial assessing respiratory protection for preventing influenza transmission.

There is a critical importance of implementing other strategies known to prevent the transmission of influenza.

“Indeed, the use of personal protective equipment such as masks and respirators should be considered the “last line of defense” in a hierarchy of infection control measures,” said the editorial.