Hospital-Acquired Respiratory Viral Infections: Incidence, Morbidity, and Mortality in Pediatric and Adult Patients

Chow, Eric J.; Mermel, Leonard A.

Respiratory viruses are clearly important pathogens causing hospital-acquired infections [8, 9] . In one study, 23% of severe nosocomial pneumonia in adults were due to respiratory viruses [10] . For decades, it has been known that nosocomial respiratory viral infections are a particular problem in pediatric patients [11] . In one study, 1 in 6 children under the age of 4 hospitalized for 1 week or more during winter or spring developed a nosocomial respiratory viral infection [12] . However, detailed studies of noninfluenza nosocomial respiratory viral infections are limited, and, to our knowledge, our study is the only one that broadly assessed the incidence of these infections in both adult and pediatric patients in a nonepidemic setting in approximately 40 years (Table 4 ). We found that rhinovirus and/or enterovirus were the predominant viruses identified among nosocomial respiratory viral infections. A previous prospective cohort study demonstrated that rhinovirus was the most commonly detected virus among children with viral respiratory infections, and approximately 20% of these infections were hospital acquired [13] . Similar to our findings, a pediatric study found that 73% of nosocomial respiratory infections were due to rhinovirus [14] . However, another pediatric study found that RSV and influenza were associated with 51% and 19% of such cases, respectively [2] . This may reflect differences in virologic diagnostic testing performed as well as the recognition of RSV in patients diagnosed with bronchiolitis at admission. Seventy-nine percent and 81% of our hospital rooms are single occupancy for our adult and pediatric patients, respectively. During the study period, our hospital infection control policy stated that adult and pediatric patients presenting with influenza-like illness should be placed in contact and droplet precautions. However, we realize that influenza-like illness may be insensitive indicator for some respiratory viral infections [15] . Nevertheless, such patients were placed in a private room, or if no private room was available, they were cohorted with patients identified to have the same respiratory virus. Despite this policy, nosocomial respiratory viral infections occurred. This most likely reflects inadequate screening of ill visitors and family or ill healthcare workers reporting for duty despite symptoms of a respiratory viral infection because these have not been stressed in recent educational efforts, and our hospital did not have a formal screening program for visitors and staff. However, based on an educational campaign and compliance monitoring, we believe that transmission of such infections in the hospital setting was less likely to be due to noncompliance with the policy, inadequate decontamination of the inanimate environment, or suboptimal hand hygiene compliance. Our hospital occupational health policy followed the Centers for Disease Control and Prevention guidelines for mitigating risk of influenza transmission from infected healthcare workers to patients that uses fever as a determining factor for which healthcare workers should not have patient contact [16] . However, such guidelines may be inadequate as previously noted [17] . Unfortunately, fever is an insensitive indicator of influenza infection in adult healthcare workers at onset of symptoms when there may be maximal risk of transmission [18, 19] . At least 1 reported influenza outbreak involved healthcare providers who apparently