Immunity against seasonal human coronavirus OC43 mitigates fatal deterioration of COVID-19

YAMAGUCHI, Tomoyuki; SHINAGAWA, Toshie; KOBATA, Hisanobu; NAKAGAWA, Hidemitsu

BACKGROUND: : The effects of high-intensity immunity on coronavirus disease 2019 (COVID-19) remain unclear. While it may be protective, antibodies against SARS-CoV-2 are more preferentially induced in inpatients with COVID-19 than in outpatients with milder disease, and immunosuppression is the standard therapy for severe cases. We studied the relationship between cross-reactive antibody production against seasonal human coronavirus and the clinical course of COVID-19. METHODS: : Among the SARS-CoV-2 immunogenic epitopes, conserved peptides in the human coronavirus OC43 were searched and synthesized. ELISA was designed to detect antibodies against synthesized peptides. Antibody titers against S2ʹ cleavage site epitopes near fusion peptides of SARS-CoV-2 and OC43 were determined in the sera of 126 COVID-19 inpatients. The correlation between antibody titers and clinical data was analyzed. RESULTS: : COVID-19 inpatients who produced antibodies against the OC43 peptide did not develop severe or fatal pneumonia. Antibody titers against the corresponding epitope of SARS-CoV-2 did not differ between inpatients with severe and mild COVID-19. The antibody titers against the OC43 epitope increased more than those against SARS-CoV-2 during the first 2 weeks of COVID-19. CONCLUSIONS: : Immunity to seasonal human coronavirus OC43 effectively enhanced recovery from COVID-19. Detecting cross-reactive antibodies to OC43 may help predict COVID-19 prognosis.