Table 2. Visits for acute respiratory illness, enrollments and RSV test results in a community cohort of adults ≥50 years old.

Season	2006–07	2007–08	2008–09	2009–10
Study enrollment period (weeks)	10	10	12	23
Percent of state RSV cases (all ages) occurring during enrollment period	63%	56%	72%	99%
No. persons in community cohort	16088	16881	17072	17694
No. persons with MAARI episode (based on ICD-9 codes) during enrollment period	901 (6%)	1332 (8%)	1269 (7%)	2133 (12%)
No. persons enrolled and tested	267	336	307	416
No. (%) positive for RSV among enrolled persons	26 (10%)	40 (12%)	46 (15%)	52 (13%)