Is there any canon or former canon evidence that Force-trained beings can protect themselves from viruses and the like? I know some Jedi can use the Force to heal injuries, and perhaps that Force-sensitives in general heal faster than others, but I couldn't find any references on that topic.
There are various example of Force users contracting mundane diseases.
Ahsoka Tano, Anakin's Padawan, contracted a virus in The Clone Wars: "Mystery of a Thousand Moons (1x18)"
PADME: ...can anyone hear—
AHSOKA: Senator Amidala, we're trapped in the safe room at the end of Complex B.
PADME: We'll be right there. Are you contaminated?
AHSOKA: I'm afraid so.
By the end of the episode, of course, Ahsoka is showing the effects of the virus quite clearly.
VINDI: The virus is liberated. You are doomed, young Jedi, along with the rest of the planet.
This indicates that the scientist who made the virus, a presumed expert, believes that it can infect and kill Jedi.
Mara Jade, a Force user of some skill, was infected with coomb spores (a Yuuzhan Vong bioweapon), as were many others.
"You couldn't reach me before I threw this. It's full of coomb spores, Jade Skywalker. The spores I painted on a hundred abominable breath masks, before that outdoor ceremony." Mara's stomach lurched. "They didn't all sicken right away," she recalled. She'd fallen ill two months later.
—The New Jedi Order: Balance Point
...but they can heal an illness or slow its course
The Jedi Cilghal, perhaps the greatest healer the Jedi had, was able to slow the course of Mara Jade's disease, although she was not truly cured until Vergere helped her. She also was able to save Mon Mothma from an infection of artificial nanodestroyers, a technique which probably would work on ordinary microorganisms.
Cilghal found other microscopic destroyers and nudged them, pushed them, herding the poison away from healthy cells, preventing further damage. The task was incomprehensibly large. The poison had spread and replicated, scattering itself through the billions and billions of cells in Mon Mothma's body. Cilghal would have to search and remove every one of them.
—Champions of the Force
It is suggested in the Star Wars RPG sourcebook Power of the Jedi that Jedi can use the Force to cure disease.
Vergere, a sometime Jedi Knight, was able to use the Art of the Small to produce tears capable of healing many things, including the coomb spore that Mara Jade was infected with. Of course, this may have had something to do with her species, but the Force was definitely involved.
Liquid gems gathered at the corners of her eyes and rolled down her muzzle, gleaming in the misty green twilight. Vergere's tears...He remembered the little vial of tears, and Mara's sudden recovery from the coomb-spore infection that everyone had privately suspected would take her life.
—The New Jedi Order:Traitor
Therefore, Jedi (and other Force-users) are not immune to disease as a matter of course, but particularly strong individuals may be able to resist or cure illness.