Human coronaviruses common in young children, may present with coinfection

In children younger than 5 years, infections with human coronaviruses OC43 and NL63 are common, and they may be characterized by lower respiratory tract involvement and substantial disease burden, according to recent findings.

In the study, researchers evaluated the medical records of all children younger than 5 years at St. Louis Children’s Hospital who tested positive for human coronaviruses(HCoVs) using a new multiplex molecular assay. The analysis included 52 children in whom the test detected HCoV-OC43 and 44 who tested positive for HCoV-NL63. For comparison, the investigators also evaluated samples of children with respiratory syncytial virus, parainfluenza virus (PIV) and picornaviruses.

Overall, picornaviruses were the most commonly isolated virus. However, the researchers found that during the course of the study, HCoV-OC43 was the fifth most common respiratory virus (4%) and HCoV-NL63 was the eighth (2%) most common virus. The test detected coinfections in 35% of the children with HCoV-OC43 and in 38% of the children with HCoV-NL63. Croup was found to be more prevalent in HCoV-NL63 (30%) than in HCoV-OC43 (2%). Notably, HCoV-NL63 appeared to be the most prevalent cause of croup in infants younger than 6 months.

The presence of lower respiratory tract infection was observed in 33% of the HCoV-OC43 patients and in 25% of the children with HCoV-NL63. When compared with other infections, there was a lower incidence of severe illness in both coronaviruses and in PIV (14% for both) than in RSV (30%) and picornaviruses (26%; P=.055 for both HCoVs vs. other respiratory viruses), and severe illness was more prevalent in patients with underlying conditions.

According to the researchers, further genomic studies will allow more complete characterization of HCoVs.

“We plan to carry out further studies of the whole genomes of the HCoVs circulating during this season, which may allow us to understand the relationship between the virus circulating in St. Louis and previously described strains of HCoV-OC43, as well as the relationship of the viral genomes to clinical manifestations, and to understand the evolution of the viruses,” the researchers wrote.