(USA TODAY) -- Here are a few common questions and answers about the flu from experts and public health officials:

Q: What are the symptoms?

A: Misery, basically. Flu comes on suddenly, accompanied by fever and chills (rare for a cold), coughing, sore throats, muscle aches, fatigue and headaches. Nausea and diarrhea are more common in children. A bad cold makes daily life rotten, but a bad flu makes it really miserable.

Q: Why is it so bad this year?

A: Flu is unpredictable, and its year-to-year spread depends on the strain of the virus, how well vaccinations match the bug (and how many people get vaccinated) and chance. This year's vaccine is actually a good match to the strain that is dominant now, Columbia University virus expert Vincent Racaniello says.

Q: Who is most at risk?

A: Most cases of the flu are mild and resolve within two weeks. The elderly are the most likely to die from flu cases that cause severe complications, such as pneumonia. Flu can also trigger severe asthma attacks and worsen chronic heart disease. Even healthy teenagers and young adults can die from complications of the flu, although young children and people with compromised immune systems face a much higher risk.

Q: Are there vaccine shortages?

A: Tom Skinner of the Centers for Disease Control and Prevention says the agency has only seen spot shortages, not large-scale ones, "so you may have to shop around" to find a pharmacy with shots left. Manufacturers made 135 million doses, and about 128 million have been distributed, with 112 million people inoculated by around New Year's Day. Typically, about 35% of the population is vaccinated every year, and this year looks similar.

Q: Is it too late to get a shot?

A: Not at all. Go get a shot. More important, get your child vaccinated, if he or she hasn't been already. For the first vaccination, children younger than 2 need two shots, spaced four weeks apart, but even one shot helps.

Q: What about prevention?

A: Get the flu vaccine. Wash your hands often, or use an alcohol-based hand cleanser, and keep them away from your face. Don't go back to work until 24 hours after your fever breaks to prevent infecting other people.

Q: Can I get the flu even after I get the shot?

A: Yes. The CDC estimates the flu vaccine is about 60% effective, on average. "Even if it isn't perfect, and we wish it was a lot better, it is a lot better than taking your chances and getting sick," Racaniello says. And people who have been vaccinated typically have weaker bouts with the flu, even if they do get sick.

Q. Why don't we have a better flu shot?

A. Because the current flu vaccine is still made with 1950s-era technology, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy.

The currently available flu vaccines stimulate immunity by including proteins found on the outer coating of the influenza virus, but these proteins change from season to season.

A better vaccine would stimulate immunity with components of the virus that don't change, providing protection for a decade or more, says William Schaffner, a professor at the Vanderbilt School of Medicine in Nashville. Early trials of a universal flu vaccine are underway, he says.

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