Secondhand smoking and pediatric asthma after respiratory syncytial virus or human metapneumovirus infection

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are common pathogens leading to lower respiratory tract infection in young children, even during the COVID-19 pandemic.1 Infection with RSV or hMPV in infancy has a reported association with the onset and/or exacerbation of bronchial asthma (BA).2,3 Secondhand smoking (SHS) is a powerful trigger for the onset and exacerbation of BA, but the additional effect on BA with the history of RSV/hMPV infection remains unclear. To clarify the impact of SHS on pediatric-onset BA in association with infection, the link of parents' smoking to the occurrence and severity of BA with the history of infection was assessed.