Factors associated with unprotected exposure to 2009 H1N1 influenza A among healthcare workers during the first wave of the pandemic.

Protecting healthcare workers (HCWs) from occupational exposure to 2009 H1N1 influenza was a challenge. During the first wave of the pandemic, many HCWs reported that they had been exposed to 2009 H1N1 when they were not using respiratory personal protective equipment. Unprotected exposures tended to be more frequent among HCWs caring for patients with atypical clinical presentations.