Antiviral photodynamic therapy basically involves:

  • administering a 'photosensitive' drug which viruses can absorb
  • shining a laser at the area infected with viruses
  • the drug reacts to the laser and damages the viruses

Here's a review on antiviral photodynamic therapy:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883714/

It seems like photodynamic therapy is effective across a broad range of microbes and I can't think of obvious dual-use risks.

There also don't seem to be many human trials, so this seems like an underfunded area and could be useful for pandemic response.

I don't have time to write a more detailed post on this but would encourage anyone reading this to do so.

(I'm experimenting with making lower-effort posts, because restricting myself to higher quality posts was resulting in me making close to 0 posts. If you think this kind of post is too low-effort and makes the EA Forum worse overall, let me know in the comments).

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Very useful. Will look at it. Thanks for the short post.

One of the main challenges of photodynamic therapy is that biological tissues absorb and scatter the light used in the therapy.[1]  This seems to limit the effectiveness of such therapies to tissue depths less than 1-2cm.

The review article cites three studies as examples of in vivo photodynamic therapy; however, none of these overcome the challenge of tissue penetration.  The first study [2] is a skin xenograft model (which needs very little tissue penetration and does not seem obviously superior to topical therapy), the second [3] pre-treats virus before inoculation (technically not an in vivo model of photodynamic therapy), and the third [4] was in oysters and used curcumin[5].

  1. ^

    https://en.wikipedia.org/wiki/Near-infrared_window_in_biological_tissue

  2. ^

    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4459584/

  3. ^

    https://pubmed.ncbi.nlm.nih.gov/22153019/

  4. ^

    https://pubmed.ncbi.nlm.nih.gov/26117199/

  5. ^

    https://www.science.org/content/blog-post/curcumin-will-waste-your-time

Thanks for adding this.

I’m still optimistic because it sounds plausible that a device / procedure can be developed to deliver the light to tissues from inside the airway.

Why does this need charitable funding rather than existing profit incentives being sufficient? Is the assumption that non-pandemic use wouldn't be profitable enough?

EA funding would just speed things up, which I think would be worth the money.

I haven’t read enough to work out why this hasn’t seem more investment yet - a potential reason is that it might be harder to protect intellectual property and profit off these treatments compared to a medication.