They were to be vaccinated against seasonal influenza - but got a basic vaccine for children instead.
A total of 103 people receiving home care in Vetlanda municipality were affected by the mistake, reports P4 Jönköping.
The incorrect vaccine - against polio, tetanus and whooping cough - had a similar name to the influenza vaccine and is, according to the municipality, harmless to those who received it.
Those affected will immediately receive the correct vaccination and the incident will be reported under the Lex Maria regulations.
"We take this very seriously and will now review the entire process regarding vaccination work to ensure it does not happen again. This includes the entire chain, from ordering to administering the vaccine", says Helen Karlsson, medically responsible nurse in the municipality, in a press release.
