Congratulations Doctor, you have been selected to study and treat various types of viruses, and create valuable vaccines. So grab your latex gloves, get your breath mask on, and head over to Virology.
As a Virologist (Also known as Pathologist or a Microbiologist), Virology can be a boring job, and most who try fail often. Just make sure the Chemist or the Chief Medical Officer are around (and attentive) or you won't be able to cure uncommon diseases in the event of an outbreak.
Main Article: Curing
This is your main job. Find a virus, analyse it, and then produce a cure. Note, the only current way of detecting whether someone has an unknown virus is to take their blood and put it in the centrifuge in virology.
If there isn't currently an outbreak on the station, you'll have to deal with infecting and injecting monkeys.
See the above guide for a detailed way of curing a virus.
The other part of your job is researching biological warfare. See more about splicing and radiating viruses in the Guide to Virology.
If you accidentally infect some one with a certain type of infectious virus, well, there is not much you can do except quarantine, treat, and ensure they aren't infectious before releasing them. Make sure only people that know exactly what they're doing can enter your room. Warn people beforehand that you're conducting experiments and remember to vaccinate yourself once you research a disease.
Being a traitor is where a dangerous job like this one really shines. Make sure you get the Heads of Staff to crack a virus crate open for you, or use a traitor item on it to pop it open yourself. Brain Rot is quite an effective way to disable the crew.
Releasing a pandemic is also a good way to cause chaos, creating a convenient cover for illicit activities. As an added bonus, curing the disease and eradicating it from the station is a good way to get in the good graces of the crew, further protecting you from any suspicion. As always, protecting yourself from the disease is most important.
NOTE: Releasing non benefical diseases when not a traitor is a great way to be banned!