This is in line with GILD comments that they estimate 90% share for Q1. This is not an end of Q1 or current market share estimate like you assert - from the prepared remarks: "We estimate that at least 90% of genotype 1 HCV patients beginning treatment in the quarter started therapy on Harvoni".
In the Q&A, GILD said the 90% figure applied to April too, so it’s the current figure for all practical purposes.