I liked this post overall, but I think it may be optimistic about the effect of challenge trials on speeding up vaccine development in a couple of the mentioned cases. I was in a malaria vaccine challenge trial 11 years ago, and if I remember correctly the same lab was also testing tb vaccines with challenge trials. I think challenge trials are a really good idea, but if they’re already being used for some of the diseases mentioned then we don’t have an opportunity to improve things much by funding more of them.
There are certainly places where HCTs aren’t the right tool—and Josh suggested that several approaches are worth pursuing—but they do seem underused compared to their value, and they are almost unique in their ability to allow testing of certain vaccines. For instance, a universal influenza vaccine is difficult to trial naturally, because you can’t see what it does or does not protect against, and you only get data about the variants circulating the current year.
And the existence of some HCT work doesn’t imply that we’re anywhere near to optimal level—yes, there have been a few hundred HCTs in the past 40 years, but they haven’t been used much or at all for many diseases, sometimes for relatively justifiable reasons that I would disagree with, and other times for no reason other than no-one has done it. (There are also cases where HCTs are, in fact, actually unethical or impossible—for example, there are some bird flus that are 100% fatal when humans catch them, but which aren’t human to human transmissible. But I’m leaving those aside for now.)
In any case, yes, this isn’t a brand new idea, but neither were mosquito nets, direct cash payments, or treating schistosomiasis—but they are effective causes nonetheless.
I liked this post overall, but I think it may be optimistic about the effect of challenge trials on speeding up vaccine development in a couple of the mentioned cases. I was in a malaria vaccine challenge trial 11 years ago, and if I remember correctly the same lab was also testing tb vaccines with challenge trials. I think challenge trials are a really good idea, but if they’re already being used for some of the diseases mentioned then we don’t have an opportunity to improve things much by funding more of them.
There are certainly places where HCTs aren’t the right tool—and Josh suggested that several approaches are worth pursuing—but they do seem underused compared to their value, and they are almost unique in their ability to allow testing of certain vaccines. For instance, a universal influenza vaccine is difficult to trial naturally, because you can’t see what it does or does not protect against, and you only get data about the variants circulating the current year.
And the existence of some HCT work doesn’t imply that we’re anywhere near to optimal level—yes, there have been a few hundred HCTs in the past 40 years, but they haven’t been used much or at all for many diseases, sometimes for relatively justifiable reasons that I would disagree with, and other times for no reason other than no-one has done it. (There are also cases where HCTs are, in fact, actually unethical or impossible—for example, there are some bird flus that are 100% fatal when humans catch them, but which aren’t human to human transmissible. But I’m leaving those aside for now.)
In any case, yes, this isn’t a brand new idea, but neither were mosquito nets, direct cash payments, or treating schistosomiasis—but they are effective causes nonetheless.