Global seasonality of human seasonal coronaviruses

Background It is speculated that the ongoing pandemic of Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 virus could recur as seasonal outbreaks, a circulating pattern observed among other pre-existing human seasonal coronaviruses (sCoV). However, little is known about the seasonality of these sCoVs on a global scale. Methods We conducted a systematic review of existing data on the seasonality of human sCoV, including NL63, 229E, OC43 and HKU1. We searched four English databases and three Chinese databases for relevant publications between 1st January 2020 and 15th April 2020. We also searched online surveillance datasets and preprints. We extracted weekly or monthly number of sCoV from included studies and calculated the monthly annual average percentage (AAP) as the relative strength of virus activity. We compared the seasonality of sCoV with that of influenza virus and respiratory syncytial virus that we previously reported. We further modelled the monthly activity of sCoV using site-specific temperature, relative humidity and dew point.