The three necessary elements to successfully proceed with a malpractice claim are liability, causation, and damages. You have to show someone did something wrong, provable by expert witnesses; that the wrong thing caused harm; and that resulted in damages. An experienced plaintiff malpractice attorney lives for the day when a case involving the wrong limb being amputated walks in the door, since liability, causation, and damages are all clear, and such a case will settle quickly with minimal time, effort, and cost on the part of the plaintiff attorney. The overwhelming majority of cases that walk in the door are not like that, and experienced counsel end up turning down those cases since they know they are not likely to win. Although it can vary by jurisdiction, 75% or so of all malpractice cases against physicians end up being won by the physicians.
Of the three elements, liability and causation are the most difficult to prove. We have seen very very few malpractice cases come out of people dying from Covid. Laypeople who have never laid hands on a patient parroting comments from Twitter, forums, and the like on how patients in the ICU should be managed does not meet the Daubert standard for expert witness testimony. The real critical care specialists who actually manage the patients were practicing in accordance with the generally recognized medical consensus, and that is the definition of the standard of care. So if you think you are going to successfully sue on the basis of how someone was managed with Covid and ended up dying, you are going to have a difficult time finding credible medical expert witness testimony on the standard of care and that this proximately caused the patient's death.