The proportions of patients with IgA antibodies against HCoV-OC43 and -HKU1 were significantly greater than those with IgA antibodies against HCoV-229E (P ϭ 0.03 and P ϭ 0.0013, respectively) and HCoV-NL63 (P ϭ 0.001 and P Ͻ 0.0001, respectively) ( Table  2) .