In individuals with fatal COVID-19 outcomes, there was a strong correlation between antibody responses to the HCoV-OC43 S2 subunit and the SARS-CoV-2 spike (Spearman’s rank correlation: P = 6.48 × 10–7), which extended to the SARS-CoV-2 RBD (Spearman’s rank correlation: P = 3.62 × 10–5) and NTD of the spike protein (Spearman’s rank correlation: P = 3.38 × 10–6), as well as the SARS-CoV-2 nucleocapsid (Spearman’s rank correlation: Figure 5, B and C; P = 0.0018). This evidence concerns the gene CHMP5 and COVID-19.