A universal masking policy for health care providers and home care workers dramatically reduced respiratory viral infections in hematopoietic stem cell transplant (HSCT) patients, researchers report.1
In particular, parainfluenza virus 3 (PIV3) – the primary threat to this particular patient group – was reduced sharply from an infection rate of 8.3% to 2.2% following the mask intervention.
“That really is the virus that was most prevalent in our population and causing the most symptoms,” says Mitchell E. Horwitz, MD, associate professor of medicine and director of the Clinical Research Adult Blood and Marrow Transplant Program at Duke University Medical Center, in Durham, NC. “Influenza and respiratory syncytial virus are much more serious, but fortunately, not as common. Whether [this intervention] would help reduce those viruses is not clear because of the relatively low numbers, but the parainfluenza was the biggest [factor] and was really the impetus for the study.”
The surgical mask policy requires all individuals in inpatient and outpatient HSCT facilities with direct patient contact to wear surgical masks regardless of symptoms or season. While standard infection control procedures are effective against respiratory infections, they may be insufficient to prevent the spread of PIV3. That is because providers and others with PIV3 may shed virus while asymptomatic, Horwitz explains. Thus, standard droplet precautions that focus on symptomatic patients may not be protective. Similarly, strategies that increase infection control measures during the winter influenza and respiratory syncytial virus (RSV) seasons neglect PIV3, which peaks in the summer months, he notes.
The Duke stem cell unit was hit hard with respiratory infections in 2009, leading to the creation of the new policy: all healthcare workers and care givers of HSCT must wear a surgical mask around the patients. The masking policy was in effect all year, regardless of season or symptoms.
The researchers compared the infection rate from the period of 2003-2009 to the post-intervention time frame of 2010–2014. Overall, respiratory infections dropped from a rate of 10.3% in the no-mask period to 4.4% after the policy. Significant decreases were seen for both allogeneic and autologous transplants. Again, infections due to PIV3 comprised the majority of the reduced infections.
We asked Horwitz to comment further on the study, which certainly suggests other centers may want to consider such a policy in the face of recurrent parainfluenza viruses in this patient population.
HIC: You found that universal masking dramatically decreased respiratory viral infections in this patient group -- what do you think was happening there? Is it possible asymptomatic workers were spreading viral infections to patients prior to the masking policy?
Horowitz: “Yes, that is certainly true, and it also was true of the caregivers that were involved with the patient management. When someone is going through a bone marrow transplant, at least in our program, they spend a lot of time out of the hospital. So, by instituting this not only by healthcare providers, but by care givers at home, I think that is how we were able to have this impact.
Often patients are coming from out of town so they are housed in an apartment. There is not as many of the typical family members or friends, although we do have some patients who come from the local area. The instructions are for anybody who gets near the patient during this period of time should be wearing a mask.
HIC: What was the reaction of the healthcare workers? Showing them such results would certainly be a validation of the policy, but did you get any pushback on masking and any signs of lack of compliance?
Horowitz: “None at all. Everyone was very compliant and they realized the importance of the issue. These are not N95 [respirators] and uncomfortable. They are surgical masks and much easier to tolerate. Anecdotally, the head nurse believes there were fewer respiratory infections among nurse staff because they were wearing masks more frequently and there were less infections being passed from nurse to nurse.”
HIC: Could there be implications for using universal surgical masking with other immune compromised patient groups, or perhaps ICUs in general?
Horowitz: “I think so. I don’t know if the non-influenza respiratory viruses are quite as significant as they are in bone marrow transplant patients. I’m sure there are occasions when patients get sick, but I think that our population is unique in the degree of lymphocyte depletion in the immune system. With standard solid tumor chemotherapy or even leukemia the neutropenia is profound and prolonged, but the lymphopenia is not quite as pronounced -- and that is where you are getting the major holes in the immune system and the susceptibility to severe viral infections. I think there would be an impact [in other populations] but I don’t think it would be quite as clinically significant.
REFERENCE
- Sung AD, Sun J, Thomas S, et al. Universal Mask Usage for Reduction of Respiratory Viral Infections After Stem Cell Transplant: A Prospective Trial Clin Infect Dis 2016; 63(8):999-1006
