LONDON — Will Nutland, a doctor in public health and research fellow in London, was in Amsterdam earlier this year when he decided to take his first tablet of a generic version of Truvada, the once-a-day pill that can help prevent HIV infection.Nutland bought the drug online from an Asian manufacturer. He didn’t know whether it would work, or harm him, or whether what he was sold was actually what had been advertised on the internet. But, like many others in the United Kingdom, he also didn’t feel like he had a choice.
