With speed of communication being limited to speed of travel, it is highly unlikely that the Traveller Universe would be able to implement any meaningful increase in border protection in response to a pandemic. Which means we either face a full biohazard assessment and quarantine for every traveller every time they pass through a starport (where that is possible), or no pandemic border security at all.

Given the "leave worlds to themselves" attitude of the 3I, and the difficulty of screening when not knowing what particular novel pathogen you might be screening for, I think the 3I would be likely to try to pick up the pieces after a pandemic has spread, rather than try to prevent the spread in the first place.

So, as a result, I think the health systems of HiTec worlds would be set up on the assumption that some sort of pandemic at the COVID level comes through once a decade or so. Lots of surge capacity! And LoTec worlds ... well, we all know what the middle ages were like!