The institute provides independent, evidence-based advice to policymakers, health professionals, private entities and the public. It is one of four groups that make up the National Academies. The study released Thursday was requested by the Centers for Disease Control and Prevention and the Occupational Safety and Health Administration. "Scientists do not know to what extent flu viruses spread through the air or whether infection requires physical contact with contaminated fluids or surfaces," a summary of the report says. It calls for "a boost in research to answer these questions and to design and develop better protective equipment that would enhance workers' comfort, safety and ability to do their jobs.""Based on what we currently know about influenza, well-fitted N95 respirators offer health care workers the best protection against inhalation of viral particles," said committee chairman Kenneth Shine, executive vice chancellor for health affairs at the University of Texas in Austin. He is a former president of the institute. "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." Health care workers should use several strategies to guard against infection, such as innovative triage processes, washing hands, disinfecting, wearing gloves, getting vaccinated and using antiviral drugs, Shine said. The institute was asked specifically to evaluate personal protective equipment designed to guard against respiratory infection, and therefore the committee focused on the efficacy of medical masks and respirators.