Does a vaccination against meningitis invalidate the fast?.
Vaccinations against meningitis do not invalidate the fast. There is nothing wrong with that, but if it is possible to give the injection at night, that is more on the safe side. And Allaah is the Source of strength. May Allaah send blessings and peace upon our Prophet Muhammad and upon his family and companions.
Standing Committee for Academic Research and Issuing Fatwas, 10/251