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Last year’s flu season was the mildest in the United States in three years. But that’s no reason to lower your guard. This viral illness can bring seven or more days of aches, fever, cough and headache. Older adults and those with underlying health problems such as asthma, diabetes and heart disease are more likely to have complications such as pneumonia, to be hospitalized — or even to die.

The most important protection is the annual flu vaccine. Its effectiveness varies, depending on how well matched it is to the flu strains that end up circulating. But it usually significantly lowers risk, reduces severity should you catch the flu anyway and, recent research shows, decreases the likelihood of hospitalization by more than 50 percent for people 50 and older. Here’s what else you need to know:

Ask about newer vaccines

As you age, your immune system may become less responsive. If you are 65 or older, ask your doctor whether you’d benefit from a high-dose vaccine (Fluzone High-Dose), which is four times stronger than the standard vaccine, or the adjuvanted vaccine (Fluad), which has an additive designed to elicit a more robust immune reaction. Studies show that both are better at preventing flu than standard flu shots, but research is stronger for the high-dose shot, says William Schaffner, a professor of preventive medicine at Vanderbilt University School of Medicine.

Check your timing

Try to have the vaccine before flu season starts, which is usually late October, says Fiona Havers, a medical officer at the Centers for Disease Control and Prevention, because it can take two weeks to build up your immunity. But if your timing is off, get the vaccine when you can: The flu usually doesn’t peak until January or February, and it can circulate for a month or two afterward.

And consider receiving the vaccine in the morning. A recent British study found that vaccines given between 9 and 11 a.m. led to higher levels of protective antibodies to two of three flu strains than those given between 3 and 5 p.m. The researchers haven’t yet looked at whether a morning shot offers more protection, but “more antibodies in principle relate to better resistance,” says study leader Anna C. Phillips of the University of Birmingham.

Humidify, hydrate and wash

Dry air helps the flu virus live longer, so consider using a humidifier to keep humidity at 30 to 50 percent, drink plenty of water and minimize your intake of alcohol, which is dehydrating. Avoid touching your nose and eyes to reduce the chance of transferring any virus you might have on your hands. Wash your hands often with soap and water for 20 seconds. Or use hand sanitizer with at least 60 percent alcohol.

Be wise about medications

Ask your doctor for a prescription for an antiviral medication right away if you develop a fever, cough and body aches and you’re 65 or older, obese or have a compromised immune system or a chronic health concern. Starting an antiviral drug within 48 hours of getting sick can shorten the flu by one to three days, ease symptoms and cut the risk of complications, Also, rest, keep yourself hydrated and, if you have fever, headache and achiness, opt for acetaminophen (Tylenol and generic), ibuprofen (Advil and generic) or naproxen (Aleve and generic). Avoid cough suppressants (flu coughs usually go away on their own) and antibiotics, which don’t work for viral infections.

More ills to guard against

Pneumonia. If you’re 65 or older, have a chronic illness or smoke, get vaccinated against pneumococcus. You will need to have two slightly different vaccines, one year apart.

Respiratory syncytial virus. This flulike infection is better known in kids, but it also strikes adults and can lead to complications including pneumonia. There’s no adult treatment, so take preventive steps such as washing your hands frequently.

Zika virus. Most infected people have no symptoms, but it can cause severe birth defects and Guillain-Barré syndrome. Some people will experience fever, joint aches, a rash or conjunctivitis. If you’re in a region where the virus is circulating, avoid mosquito bites. Go to consumerreports.org/zika for its free insect-repellent ratings.

Copyright 2016. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.