While I'm at it, I might as well do this as well:

the two key ones are, as Jeff surmises, a newer treatment for Mongoose 2 in Traveller Companion and the pretty stunning/comprehensive article in the online Freelance Traveller on Medicine in Traveller: Drugs by Rob O'Connor. (I mean in addition to JTAS 13 and Travellers' Digest 20 which I think have been noted).

(Just to clarify, this - and the earlier one on airships, is probably not exhaustive. It's a search for airship/dirigible/blimp earlier and now disease/plague/illness IN: The Traveller Bibliography (plus the 2018/2019 update), The Traveller Periodical Bibliography (plus the wip that is volume 2), and a web search on Freelance Traveller. Except that I've not done 'illness' on the latter as I must go to bed.)

HTH

plague/disease in Traveller

Double Adventure 1: Annic Nova/Shadows (GDW, 1980) – rules for disease infection

The Werewolf Disease (JTAS 5, 1980) – the players must recapture an armed man in the wilderness

Plague: Disease and Treatment in Traveller (JTAS 13, 1982) – rules for handling exposure to disease, effects of disease and treatment; tables for severity and location and notes on TL5 vaccines, TL6 anti-toxins, TL6 antibiotics and TL8 metabolics

The Day of the Glow (JTAS 16, 1983) – the PCs find themselves in the middle of a glowing plague

Mercy Mission (White Dwarf 82, 1986) – description and rules for Decal Tectitis, a rare disease affecting the foetus in the womb

The Galamone Problem III (Journal of the Senseless Carnage Society 17, 1986/7?) – the PCs suffering from an Ancient disease

Plague of Perruques (Travellers’ Digest 10, 1987) – the PCs investigate a plague

Sieben Schlafer (publisher?, 1989) – the PCs find a Zhodani noble who carries a long extinct bacterial disease [in German]

Diseases and Their Treatment (Travellers’ Digest 20, 1990) – rules for disease, effects & treatment

Nuggets (Challenge 73, 1994) – one of six patron encounters is titled Plague World

Death of Wisdom (GDW, 1995) – plague is wiping out the Hivers. Is it natural?

Double Adventures 1-6+ (FFE, 2001) – includes A Plague of Perruques (see above)

Creatures of Distant Worlds: Compendium 1 (Jon Brazer Enterprises, 2009) – one of three appendices lists diseases

#2, #3: 76 Plotlets, Parts 1 and 2: Space Adventures (Fifth Imperium #2/#3 at rpg.net, 2009) – plague is a reason a space station might be purposely abandoned

d66 Disease Names (Jon Brazer Enterprises, 2010) – 36 disease names

Options for the X-Boat Network (Freelance Traveller, Nov 2011) – one adventure hook includes experimental pharmaceuticals intended as a vaccine, destined for a planet suffering from a horrific plague

Lady Luck: A Long Night Adventure for Marc Millers Traveller (Freelance Traveller, Dec 2011) – Act III includes “R-Fever - a plague that swept the region during the fall of the Rule of Man” and is a major plot point

The Asklepios Recovery (Freelance Traveller, Dec 2014) – the PCs steal a cargo to prevent a nanotech plague [also Michael Brown, 2019 – Cepheus]

The Xero Option (Michael Brown, 2016) – the PCs help with a rare but curable disease

The Space Patrol (Stellagama, 2016) – adventure seed – The Demon Plague

The Twelve Hundred (Michael Brown, 2017) – the PCs aid a doctor whose son has a degenerative disease

Interdiction (Freelance Traveller, Jan/Feb 2018) – the PCs are asked to assist with a weapons shipment to a plague-interdicted asteroid belt

Echmerial and Incorial (Freelance Traveller, July/Aug 2018) – one of the adventure seeds has a Free Trader quarantined with Snow Plague but unfortunately the captain’s pet got past customs and is now loose in the highport

The Dangard Experiment (Freelance Traveller, Dec 2018) – the PC’s patron is succumbing to a deadly disease [also Michael Brown, 2018 – Cepheus]

Diseases, Toxins and Chemicals in Traveller Companion (Mongoose, 2019) – rules and notes on delivery, agents, exposure, resistance and acids; six examples

Medico Service (Felbrigg Herriot, 2019) – medic characters/ship; notes on diseases and rules for creating vaccines

The Asklepios Recovery (Michael Brown, 2019) – the PCs steal a cargo to prevent a cargo

Medicine In Traveller – Drugs https://www.freelancetraveller.com/features/science/tmed/med7.html - rules for a Universal Drug Profile and further rules for using the drugs; rules for poisons; rules for a Universal Infectious Disease Profile; treatment of infectious diseases; bug & drugs as weapons

Hiroshi II - https://www.freelancetraveller.com/features/culture/reference/emperors/hiroshi2.html - Late in his reign … Vilani scientist Duskir Isilguur developed the broad-spectrum antiviral drugs that finally brought the Plague of Duskir to heel

The Crucible Campaign: Travelling In the Commonwealth: The Midway Federation - https://www.freelancetraveller.com/features/othroads/crucible/polities/sabinar.html - library data for the Jehun Plague