How about this?
Have a medic class, armed with an SMG but only half the standard ammunition load, as their weapon is used mainly for defending themselves and their patients rather than going on the offensive. They can bandage flesh wounds to stop players bleeding out, and can do it faster and better than regular soldiers because of their medical training. Of course, they can't heal wounds to vital areas.
Now the main idea I have for medics comes into play when soldiers are severely wounded. What I mean by that, is when a soldier is hit in a way that doesn't kill them outright, but renders them combat ineffective, so that for gameplay's sake they are counted as dead, and respawn. So when a soldier is severely wounded, there could be a period of say 5-to-10 seconds, during which a medic can get to the soldier and "heal" him. Of course, this doesn't magically restore his health, the player still "dies" and respawns, BUT there is no reinforcement penalty for that player's "death".
In summary, medics patching up wounded soldiers doesn't heal them, but rather extends the team's reinforcements.