What about the use of antivirals to prevent infection, in the form of pre-exposure or post-exposure prophylaxis?
The reverse transcriptase inhibitors (e.g. Truvada) used for HIV PrEP (Pre-Exposure Prophlaxis) seem to also work for (treatment of) Hepatitis B. If we had platform pre-exposure prophylactics, wouldn’t that complement vaccines, or perhaps be useful for stopping outbreaks of diseases that are harder to develop vaccines against?
These pills have enough side effects that we’re not going to ask large groups of people to take them on a regular basis unless they’re genuinely at risk of exposure, but that would be true in a pandemic. At least with HIV, it also seems like taking antivirals in the 72 hours after infection[1] is pretty good at preventing infection. That seems like the sort of thing that could bring R_0 down?
That’s a good point. I seem to recall that the efficacy of (most) antivirals as prophylaxis against most diseases is approximately nil, and we can’t easily do COMPARE-style studies for prophylaxis, so I’m unsure if, in general, this is a good strategy. (And I don’t think HCTs for trying this out early on using a battery of drugs would be ethical, even ignoring sample size requirements, though perhaps animal studies could be done quickly.)
But I definitely think post-exposure prophylaxis is potentially promising, if it’s likely to work. The two challenges are that 1) it requires contact tracing far better than what we saw during COVID—though we often manage such contact tracing for HIV, so it’s not at all impossible, and 2) in most countries, I can’t imagine that the prescription / medical system would adapt fast enough to allow such prescriptions, short of them actually becoming super-competent at response. So if this is a good idea, we need lots of preparation to actually make sure it can be used.
Alternatively, I guess it could be used very early on to slow / stop initial spread, but for the cases I’m most concerned about, I don’t know how we’d know enough to try the strategy then.
The benefits of pre-exposure prophylaxis vs. vaccines have been back on my mind since reading GiveWell’s Initial thoughts on malaria vaccine approval, which concluded that seasonal malaria chemoprevention (SMC) remains more cost-effective than vaccination at present (though it’s important to note that this vaccine is much lower-efficacy than the COVID ones, in part because taking down parasites is vaccination on hard mode).
What about the use of antivirals to prevent infection, in the form of pre-exposure or post-exposure prophylaxis?
The reverse transcriptase inhibitors (e.g. Truvada) used for HIV PrEP (Pre-Exposure Prophlaxis) seem to also work for (treatment of) Hepatitis B. If we had platform pre-exposure prophylactics, wouldn’t that complement vaccines, or perhaps be useful for stopping outbreaks of diseases that are harder to develop vaccines against?
These pills have enough side effects that we’re not going to ask large groups of people to take them on a regular basis unless they’re genuinely at risk of exposure, but that would be true in a pandemic. At least with HIV, it also seems like taking antivirals in the 72 hours after infection[1] is pretty good at preventing infection. That seems like the sort of thing that could bring R_0 down?
I think this also means that your note that “the drugs take months to work” is not quite accurate, at least for this use case
That’s a good point. I seem to recall that the efficacy of (most) antivirals as prophylaxis against most diseases is approximately nil, and we can’t easily do COMPARE-style studies for prophylaxis, so I’m unsure if, in general, this is a good strategy. (And I don’t think HCTs for trying this out early on using a battery of drugs would be ethical, even ignoring sample size requirements, though perhaps animal studies could be done quickly.)
But I definitely think post-exposure prophylaxis is potentially promising, if it’s likely to work. The two challenges are that 1) it requires contact tracing far better than what we saw during COVID—though we often manage such contact tracing for HIV, so it’s not at all impossible, and 2) in most countries, I can’t imagine that the prescription / medical system would adapt fast enough to allow such prescriptions, short of them actually becoming super-competent at response. So if this is a good idea, we need lots of preparation to actually make sure it can be used.
Alternatively, I guess it could be used very early on to slow / stop initial spread, but for the cases I’m most concerned about, I don’t know how we’d know enough to try the strategy then.
The benefits of pre-exposure prophylaxis vs. vaccines have been back on my mind since reading GiveWell’s Initial thoughts on malaria vaccine approval, which concluded that seasonal malaria chemoprevention (SMC) remains more cost-effective than vaccination at present (though it’s important to note that this vaccine is much lower-efficacy than the COVID ones, in part because taking down parasites is vaccination on hard mode).