That seems like it will interfere with careless randomized controlled trial design. If the drug kills mosquitos, it could easily do less well at preventing the user from getting infected by a mosquito, but it could potentially prevent an infected patient from spreading an infection via mosquito or even kill a mosquito that would otherwise subsequently spread an infection between two other people.

In any case, here’s a better article. It seems the authors are very much aware of this issue, and they randomized entire clusters of people:

https://www.science.org/content/article/well-known-drug-coul...

https://www.astralcodexten.com/p/ivermectin-much-more-than-y...

Spoiler: this finding fits

[0] https://www.nobelprize.org/prizes/medicine/2015/press-releas...

> Four states -- Tennessee, Arkansas, Idaho, and Louisiana -- have passed OTC ivermectin laws

> [Nine] other states have bills moving through their legislatures

the reduction of infection is by reduction of mosquito population.

I remember reading some nasty mosquito diseases already landed in Florida and Southern Texas. And seems malaria use to be as far north as NH.

So, if work does not start soon, malaria could cover a decent area of the US. Of course we know the politicians will completely ignore this threat and some may even say it is no worse than the common cold. Just look at the progress on Climate Change, if decent work was done on that 30+ years ago, it would have solved lots of potential issues.

If the paper is legitimate, then the effect could be better with weekly dosing and much better with twice-a-week dosing.