Table 2. Serologic response to SARS coronavirus^a.

Clinical category	No. of patients	Paired sera available for study	No (%) of patients with 4-fold rise in antibody titer to SARS-CoV
Clinical SARS	590	417	384 (92.1)
Suspected SARS	79	11	1 (9.1)
Not SARS	379	25	2 (8.0)
Controls	45	45	0 (0.0)

^aSARS, severe acute respiratory syndrome; SARS-CoV, severe acute respiratory syndrome coronavirus.
^bAn additional 47 convalescent-phase sera were subsequently tested without any further evidence of antibody to SARS-CoV.