Their argument, essentially, why should the NHS pay for gay men to have unprotected sex.
Now, what happens if the cost of PrEP were to go up after a trade deal?
There have always been people who have said "why should it pay for self-inflicted things?" The argument has been used about smokers, the overweight, those with drink issues, and others.
It's even a sort of policy right now. In some cases, you may not get an operation, eg, unless you lose weight first.
It's not much of a leap for a politician to say "Well, we regret we can no longer fund these things in their entirety. If you want PReP, or stuff to stop smoking, or for late onset diabetes, pay 25%"
No one much. That's who
And while it was available for about £40 a month before, it's likely it would cost much more.
The cost to the uninsured in the US can be over $1600 per month.
Even a 10% contribution towards your own costs would make that prohibitive for many people.
But that doesn't mean we won't face exactly this problem with the next gen version of PrEP. Or with some other drug, for some other condition.
You don't have to "sell the NHS" to do it hard. You just have to stop it getting drugs at cheaper prices.
Most of us pay £9 per drug, per prescription. That's a bargain compared to elsewhere, and we should fight to protect.