count the number of patients who have received a microbiology test for rapid respiratory viral screen & culture since 2104.
select count( distinct admissions.subject_id ) from admissions where admissions.hadm_id in ( select microbiologyevents.hadm_id from microbiologyevents where microbiologyevents.spec_type_desc = 'rapid respiratory viral screen & culture' and strftime('%y',microbiologyevents.charttime) >= '2104' )