RT Journal Article SR Electronic T1 Oseltamivir once or twice daily safely prevented influenza JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 81 OP 81 DO 10.1136/ebm.5.3.81 VO 5 IS 3 YR 2000 UL http://ebm.bmj.com/content/5/3/81.abstract AB