Question

iterative testing for influenza vaccines
which of the statements regarding iterative testing are true of testing for influenza vaccines? select all that apply.
iterative testing is based on prediction and probability.
iterative testing will eventually lead to a universal flu vaccine.
iterative testing results in gradual changes in each years vaccine.
iterative testing makes the vaccine production process faster each year.

Explanation:

1. For "Iterative testing is based on prediction and probability": Influenza viruses mutate, so vaccine testing uses predictions (of viral strains) and probability (of effectiveness) to develop vaccines. This is true.
2. For "Iterative testing will eventually lead to a universal flu vaccine": While iterative testing helps improve vaccines, the goal of a universal flu vaccine is still a research target, and iterative testing is a means to approach it, but it's not guaranteed to "eventually" lead to it (as viral mutation complexity is high). However, more accurately, the current iterative testing for flu vaccines is aimed at adapting to yearly strains, and progress towards a universal vaccine is ongoing, but this statement's certainty is debatable. Wait, no—actually, the main point is that iterative testing for flu vaccines (due to antigenic drift/shift) is based on predicting which strains will be prevalent, so the first statement is true. The third statement: "Iterative testing results in gradual changes in each year’s vaccine"—since flu viruses change, each year's vaccine is adjusted (gradual changes) based on iterative testing of new strains, so this is true. The second statement: While research for a universal flu vaccine exists, iterative testing for yearly vaccines is about adapting to current strains, and saying it "will eventually" lead to a universal one is not a definite outcome of the iterative testing for yearly vaccines (the process for yearly is different from universal vaccine research). The fourth statement: Iterative testing is about improving vaccine match to strains, not necessarily making production faster each year. So the true statements are the first and third. Wait, let's re-express:

• "Iterative testing is based on prediction and probability": Flu vaccine development relies on predicting which influenza strains will be dominant (using surveillance data, probability models of mutation), so this is true.
• "Iterative testing will eventually lead to a universal flu vaccine": The iterative testing for yearly vaccines is focused on seasonal strains; a universal vaccine is a different research goal, and iterative testing for seasonal doesn't guarantee a universal one. So this is false.
• "Iterative testing results in gradual changes in each year’s vaccine": Each year, the vaccine is updated (gradual changes) based on the new strains identified through iterative testing (testing effectiveness against new variants), so this is true.
• "Iterative testing makes the vaccine production process faster each year": Iterative testing is about vaccine efficacy against strains, not production speed. Production speed improvements are from manufacturing advancements, not iterative testing for strain matching. So this is false.

So the true statements are the first (Iterative testing is based on prediction and probability) and the third (Iterative testing results in gradual changes in each year’s vaccine).

Answer:

• Iterative testing is based on prediction and probability.
• Iterative testing results in gradual changes in each year’s vaccine.