Question

The influenza virus, commonly referred to as the flu, is an RNA virus that infects birds and mammals. Upon infecting a host cell, the virus copies its RNA genome using a viral polymerase. Once the RNA is copied, it is translated by the host cell into the viral proteins needed to package additional viral particles. There are three strains of influenza, but most humans in the United States are infected with strain A. This particular strain constantly changes, due to the high mutation rate of the RNA copying machinery and the ability of the viral RNA segments to undergo reassortments. Although there are different influenza vaccines offered each year, it is estimated that the influenza virus still infects between 5% and 20% of the United States' population annually. Which characteristic of the influenza virus best explains why there is a different influenza vaccine offered each year?

Answer 1

The answer is: The influenza viral evolves rapidly.

Step-by-step explanation:

The explanation is that the virus that produces influenza mutates rapidly into a new form, and it is because of these mutations that the vaccine that is found at a certain moment becomes ineffective, and that is why the vaccine against viral influenza needs to be continuously synthesized, at the same production rate at which the virus mutates.

Answer 2

Answer: New vaccines are offered each year because the virus changes.

Explanation: The flue viral strain constantly changes its genetic make up, a process called antigenic drift. As the virus replicates there are small changes that creates new strains which evolve to a completely different influenza virus requiring a new type of vaccine each year.