Protecting healthcare workers against transmission of H1N1 is a primary concern in healthcare settings, but existing evidence suggests that medical masks may not be effective, in part because many healthcare workers either don't use them or use those that aren't fitted properly to their faces.
Because of that concern, an Institute of Medicine committee this week issued two recommendations on protecting workers in healthcare settings against this new influenza strain.
Workers who are in close contact with individuals, who have nH1N1 influenza or influenza-like illnesses, should use fit-tested N95 respirators, which fit better than looser medical masks, to help guard against respiratory infection.
However, the committee said, scientists do not know to what extent flu viruses spread through the air or whether infection requires physical contact with contaminated fluids or surfaces or is exclusively transmitted through airborne particles.
Because of that, the committee advocates a boost in research to answer these questions and design and develop better protective equipment to enhance workers' comfort, safety, and ability to do their jobs.
"Based on what we currently know about influenza, well-fitted N95 respirators offer healthcare workers the best protection against inhalation of viral particles," said committee chair, Kenneth Shine, executive vice chancellor for health affairs at the University of Texas System, Austin, and former president of the Institute of Medicine.
"But there is a lot we still don't know about these viruses, and it would be a mistake for anyone to rely on respirators alone as some sort of magic shield. Healthcare organizations and their employees should establish and practice a number of strategies to guard against infection, such as innovative triage processes, handwashing, disinfection, gloves, vaccination, and antiviral drug use," he said.
Studies have shown that inhalation of airborne viruses is a likely route of flu infection. However, it is not clear that airborne transmission is the sole or main way the disease spreads.
N95 respirators and medical masks both cover the nose and mouth. But medical masks are worn much more loosely, while respirators are designed to form a tight seal against skin.
If properly fitted and worn correctly, N95 respirators filter out at least 95% of particles as small as .3 micrometers, which is smaller than influenza viruses.
The report was sponsored by the Centers for Disease Control and Prevention and the Occupational Safety and Health Administration.
In a letter to the Centers for Disease Control and Prevention, Kenneth I Shine, MD, and M.E. Bonnie Rogers, chair and vice chair respectively of the Committee on Respiratory Protection for Healthcare Workers in the Workplace Against Novel H1N1 Influenza A, wrote:
"The need for research in a number of areas was striking. Due to the lack of a strong and conclusive evidence base, the committee concluded that determination of the relative contribution of each route of influenza transmission is essential for long-term preparedness planning."