Speaking of H1N1 (again, sorry), a study in JAMA compares the efficacy of N95 masks versus surgical masks. Guess what?
Our data show that the incidence of laboratory-confirmed influenza was similar in nurses wearing the surgical mask and those wearing the N95 respirator. Surgical masks had an estimated efficacy within 1% of N95 respirators. Based on the prespecified definition, the lower CI for the difference in effectiveness of the surgical mask and N95 mask was within –9% and the statistical criterion of noninferiority was met. That is, surgical masks appeared to be no worse, within a prespecified margin, than N95 respirators in preventing influenza.
I don’t imagine manufacturers of (those costly) N95 masks are very happy about this. Just wait for the counter-study. And the wails of complaint and refutation.