The first cases of the infection with HCoV-NL63 were found in young children with severe lower respiratory tract infections admitted to hospitals. While the clinical presentation of the virus can be severe, it has also been found in mild cases of respiratory infection. The comorbidity of HCoV-NL63 with other respiratory infections, has made the specific symptoms of the virus difficult to pinpoint. A study of clinical symptoms in HCoV-NL63 patients without secondary infection, reported the most common symptoms to be fever, cough, rhinitis, sore throat, hoarseness, bronchitis, bronchiolitis, pneumonia, and croup. An early study investigating children with lower respiratory tract illness, found that HCoV-NL63 was more commonly found in outpatients than hospitalized patients, suggesting that it is a common cold virus similar to HCoV-229E and HCoV-OC43, which generally cause less severe symptoms. However, the high frequency of croup is specific to HCoV-NL63 infection.
Human coronavirus NL63
SARS-CoV-2 Beta variant
Human coronavirus OC43
SARS-CoV-2 Gamma variant
Human coronavirus HKU1
SARS-CoV-2 Iota variant
SARS-CoV-2 Alpha variant
Influenza D virus