I’m not really sure what you are asking. Influenza is a disease caused by a virus. Are you trying to figure out why some people are more likely to get influenza (the flu)?

If that is your question, you might want to look up things that make people more likely to get the flu (like spending time in crowded areas), things that make people less likely to get the flu (like getting vaccinated and washing their hands) and then give people a survey about these things and whether they got the flu. You will also want to make sure they know the difference between the symptoms of a cold and the symptoms of flu before they answer that question.

If that’s not what your project is about, please describe it a bit more and I will try to help you.

Yeah, don't do the project. Influenza is caused by a virus that is transmitted by people who are infected to people who are not infected. If you hang around infected people, chances are good that you are going to get sick. There are scientists who study this sort of thing, but they use protective gear that you as a middle-school student aren't likely to have access to.

It’s important to realize that influenza is an extremely contagious and occasionally dangerous virus. Generally when people work with a virus like influenza they do it in a special “box” called a biosafety cabinet which has constantly circulating air so the virus doesn’t escape.

Also while the flu vaccine is highly effective, it doesn’t eliminate the possibility that you could get the flu. This is different than vaccines to other diseases like Measles and Polio which completely protect people. What all this means is that you should not come in contact with anyone with influenza or the virus itself because it’s dangerous. I would say you should just look up facts about influenza on a bunch of different websites and in books. While it’s useful to conduct controlled experiments to learn the scientific method, you should be careful with dangerous biological things like viruses. If you are really focused on learning about a virus with experiments, you might have more luck with the common cold, also called Rhinovirus. Of course, there is still danger in this because you could get the cold from someone.

Since so many people get a cold, you could ask people about their experiences if that fits into your objectives. Studying viruses in general has its risks, but if you want to do tests, the only one you could maybe do tests with is the common cold.