From: Rabbi Moshe Sofer
To: Rabbi Aharon Pollak
A sick person who has eaten meat need not wait the full interval before drinking whey (mei chalav). After one hour and birkas hamazon, the sick person may consume it, since the prohibition of mei chalav with meat is at most Rabbinic and the Torah's repeated phrase 'in its mother's milk' does not encompass this altered secondary extract.
Source: Shu"t Chasam Sofer YD §73