Work starts today (Thursday) to contact them and give them the correct information.
The issue arose when a mail merge error resulted in individuals being sent the Autumn /Winter version of invitation rather than the new Spring invitation letter.
But the vaccination appointment date, time and venue issued in the letter is still correct - and individuals are encouraged to attend their allocated appointment this weekend.
NHS Fife said the error arose through an administration error.
Lisa Cooper, Fife’s immunisation programme director, said: "We are really sorry for this administration error, and we are working with NHS Scotland to contact all those affected in Fife to apologise for any confusion this may have caused.
“We would, however, want to reassure recipients that they should continue to attend the vaccination appointment allocated in the letter and individuals will have the opportunity to raise any questions about their vaccination on the day, with our vaccination clinic nurses.
"With COVID infection rates remaining high, across Scotland, vaccination is one of the best ways to protect ourselves against the virus.”Lisa added: “Those identified as immunosuppressed are more susceptible to the virus and are actively encouraged to come forward for this spring booster to help to maintain their protection against Covid.
“For some people with weakened immune systems this may be their fourth or fifth dose, and that is okay, as long as you have had at least 12 weeks since your last dose.”