Use of a multiplex polymerase chain reaction assay for the early detection of an outbreak of human parainfluenza virus type 3 infection in a nursery school during the COVID-19 pandemic

INTRODUCTION: Although outbreaks of parainfluenza virus type 3 (PIV-3) have been reported in children, to our knowledge none have been reported in a nursery school. As the symptoms of PIV-3 infection are similar to those of COVID-19 infection, accurate diagnosis of PIV-3 and other respiratory viruses is important during the COVID-19 pandemic. AIMS: We experienced an outbreak of upper respiratory symptoms at a nursery school in Miyagi Prefecture, Japan, from 29/5/2021 to 13/6/2021 and aimed to determine the causative organism(s). METHODS: A multiplex polymerase chain reaction (PCR) assay which enabled rapid detection of a variety of causative microorganisms of respiratory tract infections was used to analyse 13 nasopharyngeal swabs collected during the outbreak. Infection Prevention and control measures were implemented to prevent further spread of infection. RESULTS: All 13 samples were positive for PIV-3 infection. 2 of the 13 samples were also positive for rhinovirus/enterovirus and 1 sample was also positive rhinovirus/enterovirus and coronavirus NL 63. No samples were positive for SARS-CoV-2. DISCUSSION: Children in school settings are especially vulnerable to respiratory viral infections, including COVID-19. Children under two years are unable to wear masks reliably, and the COVID-19 vaccine was approved only for older children. Multiplex PCR assays can be used for the rapid diagnosis of respiratory infections. CONCLUSION: We identified an outbreak of PIV-3 in a nursery school during the COVID-19 pandemic. The investigation of the outbreak highlighted that it was important not to overlook other respiratory infections including PIV-3 during the COVID-19 pandemic. The multiplex PCR assay provided rapid and accurate diagnosis of the causative organisms in the outbreak and helped to direct appropriate interventions to control the outbreak.