A retrospective observational study of the nosocomial outbreak caused by human rhinovirus A34

Past reports of nosocomial outbreak due to human rhinovirus (HRV) in adults are limited. We report a case of nosocomial outbreak of HRV-A34 in a long-term care facility with a literature review.

Multiplex real-time polymerase chain reaction assay (Allplex™ RV Essential Assay) was used for the detection of HRV. After whole genome sequencing (WGS), genomic data of HRV-A strains obtained from the GenBank database were used for phylogenetic comparison with outbreak strains.

A nosocomial outbreak of HRV occurred between August 22 and September 4, 2021. During the outbreak, 17 patients had respiratory symptoms and 14 patients were positive for HRV. Additionally, HRV was detected in nine asymptomatic patients. The attack rate reached 58 %. HRV was identified five days after the onset of index case and the outbreak was terminated in 13 days. There were no significant differences on their median age (37 vs 44 years old, p = 0.1221) and sex (male gender 61 % vs 39 %, p = 1.000) between symptomatic and asymptomatic HRV patients. No patients developed pneumonia and died. WGS showed that outbreak strains were genetically identical and belonged to the HRV-A34. Literature review showed past outbreaks were caused by either HRV-A or HRV-C, and the mortality rate was reported to be 22 % at highest. The present report is the first case of nosocomial outbreak of HRV-A34.

Although nosocomial HRV infection is difficult to suppress, even with strengthened infection control measures, prompt identification of HRV is important. HRV should not be underestimated, especially in long-term care facilities.