Chris, below is the response I received.
Thank you for your inquiry.
To see what rules apply to your own particular situation when entering
Switzerland, consult the online: https://travelcheck.admin.ch/home.
For further information on entry-restrictions, please consult our
FAQs.
Currently, entry for tourism purposes or visits from an SEM risk
country is only possible for fully vaccinated persons, with the last
dose within 270 days of entry (see FAQ "High-risk countries”).
Unfortunately the State Secretariat for Migration SEM is not competent
to answer your question as we are not responsible for the definition
regarding validity of vaccination.
All we can tell you is that at the moment, the Federal Office of
Public Health FOPH sets the validity date to 270 days for full
vaccination, this in accordance with EU recommendations. This
regulation can of course undergo changes as the year progresses.
Contact details FOPH: Tel. +41 58 464 44 88 / [email protected]
Please also note:
• The entry regulations are subject to continuous
change. You will always find the latest information on our website.
• This information only refers to entry into Switzerland. For
information on leaving or entering another country, please contact the
authorities of the country in question.
• When travelling by plane,
the airlines themselves decide under which conditions they transport
passengers. The Swiss authorities have no influence on this decision.
Therefore, please clarify the conditions of carriage with the
respective airline.