Harmful acts are always sinful acts? This is the conclusion of an argument that I haven’t yet seen you make yet, namely, that such harm would be a sin: We used to think the same about surgery for this reason, and even anatomical dissection of corpses to obtain medical knowledge. If you do intend to say that harming an innocent person is always wrong, then I think you must denounce surgery as people used to, because it is hurting the person (literally cutting him open, severing tissue), and we know we cannot do evil that good may come from it: The end result of cutting the person open is to do some operation once he’s cut open (removing harmful tissue, or setting some bone, inserting a stent, etc), but clearly this is a separate action that occurs after that initial action (we must first cut him open before we do whatever medical procedure we have in mind). Of course it takes time after a surgery for the person to recover and to feel better – literally, he must recover from the harm that was done to him by cutting him open, etc. I understand that sometimes they even break bones, e.g. to open up the rib cage to access the heart.
So if harming someone is always wrong, as you implied with your post, then you must be against much modern health care. If harming someone is not always wrong, then you must get into the details and explain …
Posing another question, for another example of such detail, how do you know the principle of double effect does not apply? Namely, we (both volunteer and scientist) want to do the good act of collecting data for the future protection of people, but this is done together with the undesired yet unavoidable act of causing damage to some healthy tissue. This is another argument you’ve neglected to consider. If you’re not familiar with the principle of double effect, see some “Catholic Answers LIVE” podcasts, either prolife with Trent Horn discussing ectopic pregnancies, or the bioethics shows, where it tends to come up fairly often. Or you might search on the site here, etc.