The CDC recommends we all get our flu shot as soon as our doctor or local clinics begin to offer the vaccination, usually in the early autumn, in an effort to protect each of us before flu season officially hits. If you wait until you see headlines about a major flu season underway (or your coworkers and family members start coming down with it), there’s a real chance you could be infected before that last-minute shot really starts to protect you. It takes more than a week or two for the benefits of the vaccination to take effect, so there’s the possibility that you could get your shot and then develop influenza if you were exposed to the virus either just before or after your vaccination.

So, your odds of preventing the flu from keeping you down increase if you’re vaccinated early in the flu season, but the window of opportunity is much larger than you might think. Getting your influenza vaccine sometime between Labor Day and Thanksgiving is considered ideal, but flu season doesn’t typically peak until January, February or March — some seasons it’s been known to last through May. And a late shot is better than no shot, so no matter whether it’s October or February, the vaccine can still help.

You’ve been sneezing, you have a sore throat and you’re beginning to develop a bit of a cough; don’t be disappointed that this year’s flu shot failed you — it’s likely you’re suffering something other than the flu. The common cold is often confused for the flu, but the two illnesses aren’t caused by the same thing. Additionally, only strains of the influenza virus are included in the flu vaccine. There are a few respiratory illnesses that can look a lot like colds and flu, despite being neither.

Respiratory syncytial virus (RSV), respiratory adenoviruses and parainfluenza viruses also cause upper respiratory illnesses that feel a lot like having the flu. RSV, for instance, usually develops as a cough with a stuffy nose, sore throat, earache and fever, and it can cause other conditions such as pneumonia and bronchitis. Adenoviruses also may cause respiratory infections such as pneumonia, as well as conjunctivitis (pink eye).

This may come as a surprise to many, but you can’t get the flu from the flu vaccination itself. You just can’t; the virus is in the vaccination is inactivated (that mean’s it’s been killed). You can’t get it from the nasal spray, for that matter, either. But despite this, many people’s personal experience sometimes suggests otherwise. There’s a good reason for this happening, though, and it’s not the fault of the vaccination; it’s your body. It takes two weeks, give or take a day or two, after you’ve been vaccinated for your body to build up a level of antibodies great enough to protect itself against the flu when you are exposed, but in the meantime you’re just as vulnerable as you were the day before you got vaccinated. Plus, the flu vaccine can only protect you from the known strains of the flu that were around when the vaccine was formulated. If a new strain develops, you won’t be covered.