72 Sera from 51 patients suffering from other viral or bacterial infections (influenza A virus [n = 12], influenza B virus [n = 8], respiratory adenovirus [n = 12], respiratory syncytial virus [n = 10], hepatitis B virus [n = 10], Mycobacterium tuberculosis [n = 10], other bacteria [n = 10]) as control patients for comparison with SARS patients.