Do you need the Medical exam record, that has what kind of vacination your fiance had, for any paperwork in the US?
Thanks

Vaccination record will be needed much later when adjusting status from K-Visa when you file I-485 for AOS. Vaccination record will need to be transfered to a vaccination supplement by a US Civil surgeon in the USA.

if you lost the vacination record, from the foreign country, will that affect anything, or my fiance can just get a different vacination record in the US?

When my wife interviewed for her K-1, she got vaccinated at the medical center that did the visa medical, she did the vaccinations after she got the visa. The med ctr gave her an international vaccinations book. We then had the book record transfered to a supplement in the USA by a US Civil surgeon for AOS.

Fiance can also get tested and/or vaccinated in the USA and then have the new records transfered to a supplement by US C.S..