Should I account for opponents hand (when flopping a flush draw)?

If I'm trying to calculate the odds for flush.

And i have two hearts. If I'm alone there is 50 cards left in the deck and 11 of them are hearts. So it's easy to calculate the odds.

But in a game of heads up there will be 48 cards in the deck and 2 unknown in opponents hand.

Are the odds still 11/50 or 11/48 or something else.

Forget about hand-ranges. Just two random cards in opponents hand.

Thanks in advance.