Natural SARS-CoV-2 infection triggers antibodies to multiple viral components, including both the nucleocapsid (N) and spike (S) proteins, whereas COVID-19 vaccines are designed to elicit an immune response primarily against the S protein of SARS-CoV-2, such that anti-S serology testing captures both natural and vaccine-induced immunity (5). The gene discussed is PROS1; the disease is COVID-19.