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I fully agree with Dr. Krammer here. There are a few problems with human challenge trials for #SARSCoV2 #COVID19 #coronavirus vaccines that have not been adequately addressed. https://twitter.com/florian_krammer/status/1309143153589579776
1. SARS-CoV-2 is a deadly virus, and even though younger people are at a lower risk for severe disease, the risk is not zero. Young people can and do die from COVID-19. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2770542
2. We have very little information about the long-term impacts of COVID-19 or "long COVID," but it's clear that recovering from infection does not mean recovery. Dr. @Craig_A_Spencer and I discussed this with @ASlavitt earlier this month https://podcasts.apple.com/us/podcast/toolkit-covid-long-haulers/id1504128553
2 (cont). Dr. @EricTopol wrote this piece for @ScienceMagazine discussing the issue of cardiac sequelae and has a good thread here: https://twitter.com/EricTopol/status/1308981698701545473?s=20
3. This trial proposes using remdesivir as a rescue therapy. Remdesivir has not shown a substantial mortality benefit, so it's a stretch to call it a rescue therapy. See this perspective in @bmj_latest: https://www.bmj.com/content/369/bmj.m1798.short
4. The information obtained from a human challenge trial is necessarily limited. These trials will at most include a couple hundred participants. They are underpowered compared to an authentic phase 3 trial involving thousands of patients.
4 (cont). Using a human challenge study involving only young, healthy volunteers will not provide any information about how a vaccine will work in more vulnerable populations. And I have yet to see a person of color interviewed about how they can't wait to be a human volunteer.
4 (cont). We already know that some vaccines are age-dependent in terms of efficacy, so with a human challenge trial involving only young, healthy participants, you won't be able to evaluate that at all. Same with HIV status or any other immune/inflammatory co-morbidity.
4 (cont). I fail to see how human challenge studies would provide very much useful data at all in terms of efficacy outside of the narrow group being allowed to participate. So how does that accelerate vaccine approval? It doesn't.
5. Comparisons to human challenge studies for malaria, dengue, influenza, etc. are not germane. We either have rescue therapies and/or use viruses that are known to be low pathogenicity. We don't know much about what predisposes young, healthy people to severe COVID.
5 (cont). There are NO known attenuated SARS-CoV-2 isolates in people. And NO, using D614 instead of G614 does not address this. There is no evidence that this—or any—mutation decreases virulence.
6. There are multiple phase 3 trials that will have data by the time this human challenge study starts. So...what's the point of doing this AFTER those trials read out? Any knowledge gained from this study will be incremental at best.
So my question is, if human challenge studies are ethically dubious and present a great and unknown risk to participants, and if they won't result in useful information, why go through all the trouble of doing them when we will get much better data from phase 3 trials?
