This depends on what is meant by research. If you have no natural curiosity to understand how things work and how to fix them, then yes, that will be recognized negatively. If you were too busy caring for people who needed to be helped and did not do 1000 pcr reactions or mouse surgery, that is ok at any medical school.
You would rarely get into a biomedical MD/PhD program without doing research, but many medical students get accepted into MD programs without doing any research. It is a good idea to have done something, even if it is small. For most people, this is a "yes I did it" or "no I hate it" category.
So what is research? We are talking about medical research. Realize that a lot of people do research outside of biomedical lab. Not all projects are published in Science, Nature, and the New England Journal. Examples: helping someone write a case report or a case review, biostats, public health, cost benefit analysis, preparing a book chapter, figures, doing a talk or poster presentation helping someone work up a difficult patient case....normally academic doctors would be pleased to give you some work to do, even for a short time. A short summer session of research is about average for most people who apply.