The flu is an illness that you hear so much about year after year that it’s easy to assume you know all there is to know about it. That’s a mistake. Widely held assumptions about the flu often are wrong—and dangerous. By learning the facts, you can help yourself and loved ones from being among the estimated 36,000 Americans who will die this year due to pneumonia and other flu-related complications. Common misconceptions…

Misconception #1: People who have the flu are contagious only when they have symptoms. Actually, most people with the flu are able to spread the illness beginning about a day before showing any symptoms and up to seven days after symptoms begin.

And you don’t even have to be in very close proximity. The influenza virus can spread to a person six feet away—mainly when the sick person sneezes, coughs or even talks. Of course, you can also become contaminated if you touch your eyes, nose or mouth after coming in contact with an object, such as an elevator button, handrail or doorknob, that harbors a flu virus. These viruses can live up to eight hours on such objects.

Helpful: Wash your hands or use hand sanitizer several times a day—and always after you’ve been out in public or in contact with someone who has the flu.

Also: If you get the flu and have a fever, stay home until your fever has been gone for at least 24 hours without the use of fever-reducing medication.

Misconception #2: If you’re not running a fever, you don’t have the flu. Flu symptoms aren’t always predictable. A fever is common with the illness, but it doesn’t occur in everyone. Typical flu symptoms include body aches, extreme fatigue and a dry cough. However, some flu patients may also experience sneezing, a stuffy nose and sore throat—symptoms that usually occur with the common cold. In rare cases, flu patients even suffer vomiting and diarrhea. Although flu symptoms vary, a hallmark of the illness is that it comes on quickly and makes you feel quite sick.

Misconception #3: If you think you have the flu, you should go right to bed until you feel better. Getting plenty of rest is important for flu recovery, but if you suspect that you have the flu and are in the high-risk category for flu complications (for example, you are over age 65, pregnant or have a chronic health condition such as asthma or heart disease), you should also alert your doctor right away.*

He/she may recommend a rapid flu test (using a nose or throat swab) that can diagnose the flu in about 30 minutes. If the result is positive, you may be prescribed the antiviral medication oseltamivir (Tamiflu). Key: This drug works best when started within 48 hours of getting sick.

Important: Adults produce much less of the flu virus and for a shorter time than children. If the rapid flu test is negative, it doesn’t necessarily mean that you don’t have the flu, and your doctor may want to treat you anyway.

If you’re generally healthy and get a mild case of the flu, you may simply want to get a lot of rest and drink plenty of fluids. To control symptoms, you can use over-the-counter drugs—cough medicine or acetaminophen (Tylenol) or a nonsteroidal anti-inflammatory drug such as naproxen (Aleve) for fever, if necessary.

Misconception #4: The flu vaccine must be given early in the season to be effective. You will certainly have protection for a greater part of the flu season if you get vaccinated early on, but it’s still worth getting the vaccine even as late as January if the flu is still circulating. But don’t wait! It takes about two weeks for the vaccine to trigger the development of antibodies and confer maximum protection.

Misconception #5: All flu vaccines offer the same level of protection. Again, not true. Traditional flu vaccines, known as trivalent vaccines, protect against three types of viruses—two strains of Type A (which cause the most severe illness) and one Type B strain.

New option this year: Manufacturers have introduced quadrivalent vaccines, which add a second type of B strain to the mix. It is more likely than older vaccines to protect against the variety of virus strains that circulate each year.

Ask your doctor—or the pharmacist where you get your shot—if the new version is available. The extra protection is worth it. The “quad” vaccine will probably become standard in the next few years. This year, however, it will be in short supply because manufacturers haven’t fully changed their operations.

Important: If the quad vaccine is not available in your area, don’t skip your vaccination.

Misconception #6: People who are allergic to eggs can’t get a flu vaccination. A new vaccine, Flublok, doesn’t use eggs in production—as do traditional vaccines that culture flu viruses in eggs. Instead, it’s made with recombinant DNA technology in which insect viruses are used to produce a protein found in flu viruses. The vaccine is FDA-approved for adults ages 18 to 49 (the ages of people in a study that was performed). It is just as effective as egg-based vaccines.

Misconception #7: The flu vaccine doesn’t work very well. Last year, the CDC reported that the flu vaccine was about 56% effective at overall prevention and about 27% effective in adults age 65 or older.

The immune system gets less robust with age. It produces fewer antibodies in response to vaccines. To help older adults, manufacturers have recently introduced a higher-dose vaccine that research has shown to be about 24% more effective than older vaccines.

Important: These percentages may seem low but represent complete prevention in people who respond to the vaccine. Even though the flu vaccine isn’t effective for everyone, it’s better than no protection. The vaccine also makes the flu milder in people who do get it and reduces deadly complications such as pneumonia.

If you are age 65 or older, your doctor or pharmacist will probably recommend the Fluzone High-Dose vaccine. Note: A small percentage of people will have arm soreness and/or a headache.

Misconception #8: All flu shots contain mercury. Questionable research that once claimed that the mercury-containing preservative thimerosal caused autism in children has been completely debunked. Even though there’s no credible evidence of harm caused by thimerosal, some people refuse to get a flu shot because they are still concerned about the preservative and assume that all flu shots contain it. If you would rather avoid thimerosal, ask your doctor for a single-dose flu vaccine (the preservative is used only in multidose vials that provide vaccine for multiple injections). The FluMist nasal spray also doesn’t contain thimerosal.

Too Healthy to Get the Flu? Think Again!

Many people believe that if they’re basically healthy, they won’t benefit from flu vaccination and that only high-risk individuals need the vaccine. That’s absolutely false. Perhaps you’ve dodged this bullet in past flu seasons, but that doesn’t mean you will this year or in any future year. While it’s true that people in high-risk groups are more likely to develop potentially deadly complications (such as pneumonia, dehydration and even heart attacks) from the flu, many perfectly healthy people contract the flu each year, and some of those cases turn out to be devastating.

Even people without symptoms can spread the flu: Younger adults (in their 20s and 30s) can get the flu but have no symptoms and pass it on to others, including those in high-risk categories. If younger adults get vaccinated, it helps cut down on the spread of the virus.

*For the entire list of CDC flu recommendations, go to CDC.gov/flu.