assalam o alekum.During the swan (roza) time can give 10ml blood to HIV test.

Answered according to Hanafi Fiqh by

بسم الله الرحمن الرحيم

(Fatwa: 1496/1496/M=1431)

Blood donation does not nullify the fast. One can give blood at the time of need and compulsion.

Allah knows Best!

Darul Ifta,
Darul Uloom Deoband