when did patient 19627 last receive prescriptions for vancomycin since 01/2101?
select prescriptions.startdate from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 19627 ) and prescriptions.drug = 'vancomycin' and strftime('%y-%m',prescriptions.startdate) >= '2101-01' order by prescriptions.startdate desc limit 1