60% of the people have been vaccinated, so 40% have not.
The probability of getting five people in a row that aren't vaccinated is (0.40)^5 = 0.01024
Subtract this from 1 to get the probability of at least one vaccinated person in the sample of five.
1-0.01024 = 0.98976
This works because the events "at least one vaccinated" and "none vaccinated" are complementary. One or the other must happen, which means the two probabilities add to 1.
