Question

question 4 of 5
why do vaccine makers have to guess which flu strains will be active months before the flu season begins?

a. vaccines must be administered over months.

b. transporting flu shots to doctors takes time.

c. it is difficult to convince people to get vaccinated.

d. vaccines take a long time to make.

Explanation:

To determine the answer, we analyze each option:

• Option A: Vaccine administration time doesn't relate to why makers guess strains early.
• Option B: Transport time is about distribution, not strain guessing timing.
• Option C: Convincing people to vaccinate is unrelated to strain prediction timing.
• Option D: Vaccines have a long production timeline, so makers must guess strains early to have vaccines ready for flu season.

Answer:

D. Vaccines take a long time to make.