Dose Stretching for the Monkeypox Vaccine

Photo Credit: NIAD. https://www.flickr.com/photos/niaid/52103767506/

We are making all the same errors with monkeypox policy that we made with Covid but we are correcting the errors more rapidly. (It remains to be seen whether we are correcting rapidly enough.) I’ve already mentioned the rapid movement of some organizations to first doses first for the monkeypox vaccine. Another example is dose stretching. I argued on the basis of immunological evidence that A Half Dose of Moderna is More Effective Than a Full Dose of AstraZeneca and with Witold Wiecek, Michael Kremer, Chris Snyder and others wrote a paper simulating the effect of dose stretching for COVID in an SIER model. We even worked with a number of groups to accelerate clinical trials on dose stretching. Yet, the idea was slow to take off. On the other hand, the NIH has already announced a dose stretching trial for monkeypox.

Scientists at the National Institutes of Health are getting ready to explore a possible work-around. They are putting the finishing touches on the design of a clinical trial to assess two methods of stretching available doses of Jynneos, the only vaccine in the United States approved for vaccination against monkeypox.

They plan to test whether fractional dosing — using one-fifth of the regular amount of vaccine per person — would provide as much protection as the current regimen of two full doses of the vaccine given 28 days apart. They will also test whether using a single dose might be enough to protect against infection.

The first approach would allow roughly five times as many people to be vaccinated as the current licensed approach, and the latter would mean twice as many people could be vaccinated with existing vaccine supplies.

…The answers the study will generate, hopefully by late November or early December, could significantly aid efforts to bring this unprecedented monkeypox outbreak under control.

Another interesting aspect of the dose stretching protocol is that the vaccine will be applied to the skin, i.e. intradermally, which is known to often create a stronger immune response. Again, the idea isn’t new, I mentioned it in passing a couple of times on MR. But we just weren’t prepared to take these step for COVID. Nevertheless, COVID got these ideas into the public square and now that the pump has been primed we appear to be moving more rapidly on monkeypox.

Addendum: Jonathan Nankivell asked on the prediction market, Manifold Markets, ‘whether a 1/5 dose of the monkey pox vaccine would provide at least 50% the protection of the full dose?’ which is now running at a 67% chance. Well worth doing the clinical trial! Especially if we think that the supply of the vaccine will not expand soon.

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