In those with all swab specimens ( n = 1134 ) , oseltamivir significantly reduced virus isolation on days 2 ( placebo 374 [ 66 % ] vs oseltamivir 321 [ 56 % ] ; difference 15.2 % , 95 % CI 9.5-20 .8 , p = 0.0004 ) , 4 ( 241 [ 43 % ] vs 174 [ 30 % ] ; difference 30.2 % , 95 % CI 24.6-35 .8 , p < 0.0001 ) , and 7 ( 68 [ 12 % ] vs 36 [ 6 % ] ; difference 47.5 % , 95 % CI 44.2-50 .8 , p = 0.0009 ) .