Human coronavirus NL63 infection and other coronavirus infections in children hospitalized with acute respiratory disease in Hong Kong, China

Background. Human coronavirus NL63 (HCoV- NL63) is a recently discovered human coronavirus found to cause respiratory illness in children and adults that is distinct from the severe acute respiratory syndrome (SARS) coronavirus and human coronaviruses 229E (HCoV- 229E) and OC43 (HCoV- OC43). Methods. We investigated the role that HCoV- NL63, HCoV- OC43, and HCoV- 229E played in children hospitalized with fever and acute respiratory symptoms in Hong Kong during the period from August 2001 through August 2002. Results. Coronavirus infections were detected in 26 (4.4%) of 587 children studied; 15 (2.6%) were positive for HCoV- NL63, 9 (1.5%) were positive for HCoV- OC43, and 2 (0.3%) were positive for HCoV- 229E. In addition to causing upper respiratory disease, we found that HCoV- NL63 can present as croup, asthma exacerbation, febrile seizures, and high fever. The mean age (+/- standard deviation [SD]) of the infected children was 30.7 +/- 19.8 months ( range, 6-57 months). The mean maximum temperature (+/- SD) for the 12 children who were febrile was 39.3 degrees C +/- 0.9 degrees C, and the mean total duration of fever (+/- SD) for all children was days (range, 1-5 days). 2.6 +/- 1.2 HCoV- NL63 infections were noted in the spring and summer months of 2002, whereas HCoV- OC43 infection mainly occurred in the fall and winter months of 2001. HCoV- NL63 viruses appeared to cluster into 2 evolutionary lineages, and viruses from both lineages cocirculated in the same season. Conclusions. HCoV- NL63 is a significant pathogen that contributes to the hospitalization of children, and it was estimated to have caused 224 hospital admissions per 100,000 population aged <= 6 years each year in Hong Kong.