Episodes Referenced:

The Next Generation:

“Unnatural Selection” (TNG - 2x7) - Pulaski tries to cure a group of scientists on a space station that are aging rapidly

“Contagion” (TNG - 2x11) - The crew investigates the destruction of their sister ship, the Yamato

Deep Space Nine:

“Babel” (DS9 - 1x5) - A virus spreads through the station

“The Quickening” (DS9 - 4x24) - Dr. Bashir tries to cure a plague affecting a planet

Voyager:

“The Phage” (VOY - 1x5) - The crew meets a species, the Vidiians, whose entire civilization revolves around a disease and Neelix’s lung is removed

“Lifesigns” (VOY - 2x19) - The Doctor helps a Vidiian doctor survive

“Resolutions” (VOY - 2x25) - Janeway and Chakotay are left behind on a planet to battle a disease

“Macrocosm” (VOY - 3x12) - A macroscopic virus attacks the ship and crew

Enterprise

“Observer Effect“ (ENT - 4x11) - Silicon-based virus infects crew members who have to quarantine

Your Star Trek Pandemic-Themed Watch List (StarTrek.com, March 23, 2020)