[kiallmacinnes]

Theres a whole extra layer of legal complexity here :)

e.g. some countries will consider you fully vaccinated X weeks after your 2nd jab of a specific vaccine. Others will say it's X+1 weeks.

The system has been built so that these decisions aren't in the cert itself, rather each country can layer on "business rules" on top. So - even if the cert expiry date is likely to be set far into the future, that has zero bearing on if it will be accepted or considered expired.