Some Flu Patients May Pose Greater Risk to Healthcare Providers

One in five flu patients exhales so much more of the airborne virus than other flu patients, that researchers are asking whether these "super emitters" pose a greater likelihood of transmitting  the virus to the people near them.

Werner Bischoff, MD, assistant professor of infectious diseases at Wake Forest Baptist Medical Center in Winston-Salem, NC, and lead author of a study published in the Jan. 31 online edition of The Journal of Infectious Disease, told HealthLeaders Media that more research is needed before he can determine the potential threat that super emitters may present to healthcare providers.  

"It's too early at this stage to offer any broad recommendations to healthcare providers or caregivers overall," Bischoff says. "The study looked at the release of the influenza virus. We did not look at the transmission patterns. We need to take a further step to find out how influenza is transmitted and what we can do to prevent it."

The study examined 94 patients at Wake Forest Baptist who were screened for influenza symptoms during the 2010-2011 flu season. Nasal swabs were taken, and air samples were obtained from within one foot, three feet and six feet of patients during routine care.

Of the 94 patients, 61 tested positive for the flu virus and 26 released influenza into the air. Five of the patients emitted up to 32 times more virus than the others. Those patients also reported a greater severity of illness.

Bischoff says researchers could not find a way to proactively identify the super emitters. "We collected a lot of data from these individuals and we looked into that, but it was a pilot study so we had a very limited amount of participants," he says.

"So, we tested pretty much everything that we collected from them: from vaccinations to other medical conditions they may have had to age-related factors. Nothing could be matched, but that doesn't mean there couldn't be a link between some of these factors and the super emitters' status by itself. Next would be to look at that in a larger study overcoming the limitation of the pilot study."

"If we can identify them we can implement some preventive measures, be it face masks or anything else we can come up with to protect any caregivers that come into close contact with them."

It is generally believed that the flu virus spreads mostly through large particles emitted within three to six feet of the infected person. As a result, existing infection-control efforts for bedside providers have required the use of fitted respirators during bronchoscopies, intubations, cardiopulmonary resuscitation, and other aerosol-generating procedures.

However, Bischoff says that most of the influenza virus in air samples collected for the study was found in small particles during routine care up to six feet from the patient's head. Those small particles float in the air for hours and can travel relatively long distances, and can more easily penetrate non-fitted protective masks.

"Everybody emitted the virus up to six feet from the patient's bed. It was pretty much at the end of the patient bed when you stood in front of it," Bischoff says.