"Ultimately, however, Factor VIII killed many of those who infused it in the 1970s and 1980s. For decades, British officials and ministers claimed that the contaminated blood scandal was a tragedy no one could have prevented: when haemophiliacs began to be infected, hepatitis C hadn’t even been named, and HIV/Aids was entirely unknown; new protocols were introduced once the dangers became clear. According to Margaret Thatcher, ‘all patients received the best treatment available in light of the medical knowledge at the time.’ These claims were not true."
https://www.lrb.co.uk/the-paper/v45/n22/florence-sutcliffe-braithwaite/we-ve-messed-up-boys