I use either interchangeably. I think I use the latter more frequently.

Movie theater is definitely more of an American thing. I've never heard any American say, "Hey, let's go to the cinema." As someone else said, "Let's go to the movies," is the most common phrase. 

The influenza epidemic is a very important problem for the Japanese government to solve as soon as possible, because the notorious disease has led to many deaths, especially the elderly and young children. Although drug manufacturing companies develop and provide vaccinations every year, we haven’t acquired an effective preventative method yet. This is because the influenza virus changes its own formation every year and the companies have to foresee the variation and develop vaccines before the epidemic outbreak. Therefore, it’s hard for us to completely prevent the virus with only vaccination. We have to take another countermeasure to prevent infection.

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Very good short article! I changed a few words that sounded a little odd based on context. Especially with diseases, it's more common to use prevention, although protect isn't necessarily wrong. It's easier and more natural to say, "prevent disease," than, "protect against disease." Also, "elderly persons" isn't really wrong either, but a better way in this context would usually be, "the elderly" or, "elderly people."