Why did Dimitri most likely get the flu? Dimitri received a flu vaccination earlier in the year. However, he has just been tested and has a confirmed case of the flu.

A flu vaccination lowers the chance of getting the flu, but it does not guarantee complete protection. Dimitri could still have become infected despite being vaccinated, so “Vaccinations are not always effective” is the best answer. Vaccines do not cause a full case of the flu, and they do not need to be given at the onset of illness to work.

AI-written and checked against the verified answer.