Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Normally, the influenza virus changes its structure slightly for each passing year. Although, we are being exposed to these “modified” or slightly mutated and evolving influenza strains every year, we do not always come down with the flu disease even if we have not received the yearly influenza vaccine. However, sometimes, we do get a really bad case of the flu, despite the fact that we have memory cells left from previous infections with the influenza virus.
Reason R: This is a concept of original antigenic sin, which suggests that we only mount a primary response once we have exhausted the potential to use our memory cells to eradicate the infection. Since most of our first encounters with influenza will vary, the years in which “all” of the key influenza epitopes are significantly “new” to each of us will also vary. It is only in these years that we experience a new primary response to influenza virus, and therefore symptoms of the flu are most severe.
In the light of the above statements, choose the correct answer from the options given below
