Well, for a long time, the vast majority of effective major medical therapies were in infections and a few surgerical interventions. Child birth was more common, but most were conducted without a physician present, and indeed, physicians contributed to poor outcomes.
Semmelweis noted the correlation between the participation of doctors/studentsand poor outcome in the 1840s, and propounded a crackpot system of cleanliness including such outlandish measures as washing your hands after dissecting cadavers and squeezing ous out of boils. The incidence of puerperal (childbed) fever dropped dramatically, so naturally Semmelweis died in poverty and disgrace.
If you were raised in the South, as I was, you were probably taught that Crawford Long invented ether anaesthesia in 1842, but up north, ether was mostly used recreationally for the next few years (“ether frolics” were popular among physicians and students), Boston area doctors (among which I now number myself, so I can mock them) apparently took the Antoinettesque view that “it’s entirely too good for them”, until William TG Morton began doing demonstrations at the Massachusetts General Hospital about 1846. He certainly inspired a steady trickle of medical articles in the Boston medical journals, and is credited as the inventor by the Yankees.
Anaesthesia is not just a comfort measure. The pain of surgery alone can readily cause shock and death. Today, anaesthesiologists often describe their job as "desperately trying to keep the patient alive while the surgeon at the other end of the table does his damnedest to kill them. As someone who’s done surgery, but no ansetheiology since med school, I must confess I agree.
Pasteur’s work with vaccines, aseptic technique (sterilization, airborne contamination, and more) didn’t come until the 1860s. At around that time, Lister was pioneering chemical antiseptics and aseptic techniques in surgery. Some of his other milestones, like the use of catgut instead of silk (publ. 1884, IIRC) are probably as important but little heralded.
Koch, in the 1870s, was the first to prove links between specific types of bacteria and specific diseases. Dmitri Iwanowski did the first good work on viruses in the 1890s, but had no idea what they were. Actually his work was on a tobacco virus. Close enough.
Until the 1930s, you could get a correspondence school medical degree in a year or less from Harvard Medical School,a nd in a matter of days or weeks from less reputable schools like Columbia (which is now among the finest American medical schools) To find out more, Gooogle the “Flexner report”.
Fleming discovered the first truly effective antibiotic (penicillin) in the 1920s, but use was not at all widespread until the 1940s. Prior to the use of antibiotics, most antibacterial therapies seemed to be toxic compounds of arsenic, strychnine, mercury and the like, administered on the principle that the germs, being smaller, would probably die first. The basic idea was just to break the balance between man and germ, so the human immune system could get the upper hand. Even in modern medicine, the largest part of the cure (whether combating infections or healing) is actually done by the patient’s body. Even with our fanciest drugs and techniques, treating a patient who is immunocompromised or has impaired healing is a drawn-out struggle with an iffy outcome.