Short answer about vaccines

[Anna232]

Aren't my sentences wrong without the comma and the article before "flu"? If I am not mistaken "the reason" is followed by "why" and in the last sentence I think I can also use "a vaccine."
Context: It is my short answer to the question whether it is a good idea to get vaccinated or not. I wrote the sentences but when I read them I thought it could be either option in some of them. Am I right?

First of all, it is important to know what the flu vaccine is(,) to be able to decide if we really need them. It reduces the risk of getting (the) flu and helps your body fight the/a virus easier if you get sick. Vaccinated people can fight off (the )flu easier. However, the symptoms after getting the vaccine might be: fever, weakness and running nose. These symptoms are the reason (why) people are against getting (the) vaccines.

 

[Lwords]

You are mostly right: "the flu" is more natural in most of your sentences, and it"s better to use the comma after "is" in the first sentence. "The reason why" is common, but "the reason people are against getting vaccines" is also fine. In the last example, both "a virus" and "the virus" can work, depending on whether you speak in general or about a specific case. "A vaccine" and "the vaccine" are both possible, but with "the vaccine" you mean a specific one (the flu vaccine).

 

[emsr2d2]

For info, in BrE, just "flu" is still more common.

I think I've got flu.
He was laid up with flu last week.
Vaccinated people can fight off flu more easily.
It reduces the risk of getting flu.

 

[Tarheel]

Say:

First of all, it's important to know what the flu vaccine is to be able to decide if we really need it.

 

[Anna232]

Say:

First of all, it's important to know what the flu vaccine is to be able to decide if we really need it.

So the comma is optional after "is", isn't it?