Robert Dyrdak, Emma B. Hodcroft, Martina Wahlund, Richard A. Neher and Jan Albert
medRxiv, vol. , 2020.10.01.20205096, 2020
10.1101/2020.10.01.20205096
Abstract
{\textless}h3{\textgreater}Objectives{\textless}/h3{\textgreater} {\textless}p{\textgreater}The four seasonal coronaviruses 229E, NL63, OC43, and HKU1 are frequent causes of respiratory infections and show annual and seasonal variation. Increased understanding about these patterns could be informative about the epidemiology of SARS-CoV-2.{\textless}/p{\textgreater}{\textless}h3{\textgreater}Methods{\textless}/h3{\textgreater} {\textless}p{\textgreater}Results from PCR diagnostics for the seasonal coronaviruses, and other respiratory viruses, were obtained for 55,190 clinical samples analyzed at the Karolinska University Hospital, Stockholm, Sweden, between 14 September 2009 and 2 April 2020.{\textless}/p{\textgreater}{\textless}h3{\textgreater}Results{\textless}/h3{\textgreater} {\textless}p{\textgreater}Seasonal coronaviruses were detected in 2,130 samples (3.9\%). OC43 was most commonly detected (28.4\% of detections), followed by NL63 (24.0\%), HKU1 (17.6\%), and 229E (15.3\%). The overall fraction of positive samples was relatively similar between seasons. In contrast, at species level there was distinct pattern of biennial alternating peak seasons for the \textit{Alphacoronaviruses}, 229E and NL63, and the \textit{Betacoronaviruses}, OC43 and HKU1, respectively. The \textit{Betacoronaviruses} peaked earlier in the winter season (Dec-Jan) than the \textit{Alphacoronaviruses} (Feb-Mar). Coronaviruses were detected across all ages, but diagnostics were more frequently requested for paediatric patients than adults and the elderly. The species showed different age distributions, with OC43 and 229E positivity being relatively constant across age strata, while the incidence of NL63 and HKU1 decreased with age.{\textless}/p{\textgreater}{\textless}h3{\textgreater}Conclusions{\textless}/h3{\textgreater} {\textless}p{\textgreater}Both the \textit{Alphacoronaviruses} and \textit{Betacoronaviruses} showed alternating biennial winter incidence peaks, which suggests some type of immune mediated interaction. Symptomatic reinfections in adults and the elderly appear relatively common. Both findings may be of relevance for the epidemiology of SARS-CoV-2.{\textless}/p{\textgreater}