Once upon a time, in a land very much like yours, there were reliable, not-magic ways to keep people healthy and avoid a whole roster of dreadful diseases — diseases that pock your skin (measles and chickenpox), swell your face (mumps), clog your lungs (diphtheria, whooping cough, pneumonia, influenza) and, for some, cause premature death.

But folks started to think that those ways — let’s call them “vaccines” — were somehow bad for you or not worth it. They didn’t understand that vaccines’ power to prevent disease compared with the risk that a shot might cause very bad reactions was 40,000-to-1. So, when it comes time (every year) to get the flu shot, we have to make the case all over again.

Consider this: During last year’s flu season (through May), the Centers for Disease Control and Prevention estimated that the influenza virus caused 36,400 to 61,200 deaths and 531,000 to 647,000 hospitalizations. The overwhelming majority of children who died in the 2018 epidemic had not been vaccinated. Even during the 2017-2018 season, which lasted longer than usual and caused a lot more infections than usual — and had a vaccine effectiveness rate of between 62% and 22% against various strains — the CDC says flu vaccines prevented 7.1 million illnesses, 3.7 million medical visits, 109,000 hospitalizations and 8,000 deaths.

So, the flu vaccine is available, and you should get it — the sooner the better. Here’s the information you need:

WHO SHOULD GET IT

The CDC recommends annual influenza vaccination for everyone 6 months and older with any licensed influenza vaccine that is appropriate for the recipient’s age and health status (that information is below), and it expresses no preference for any one vaccine over another.

However, if you or your child has any chronic or acute health issues, ask your doctor what influenza vaccination guidelines and recommendations apply specifically to you. Don’t just go get a shot at a local pharmacy without having that conversation first.

Of special note: The CDC says the vaccine is an increased priority for anyone with a BMI of 40 or greater; residents of nursing homes and long-term care facilities; people who are immunocompromised; pregnant women; adults and children who have chronic pulmonary (including asthma), cardiovascular (excluding isolated high blood pressure), renal, hepatic, neurologic, hematologic or metabolic disorders — including diabetes; children from 6 months up to their fifth birthday; and everyone 50-plus. That’s because chances are, the flu will be more severe and cause more complications for these folks.

WHAT IT IS

The vaccines have been updated from last year’s, so hopefully they will be even more effective. There are inactivated trivalent vaccines (regular and high-dose) that cover three strains of the flu and inactivated quadrivalent shots that cover four strains. The Afluria Quadrivalent IIV4 vaccine (along with the other quadrivalent vaccines) is now available to anyone 6 months of age or older; Afluria used to be just for those 5 or older.

One recombinant influenza vaccine, Flublok Quadrivalent (RIV4), is indicated for people 18 and older and is made without the use of influenza viruses (it has antigens) or eggs.

HOW IT’S ADMINISTERED

Kids 6 months through 8 years old who have never had a flu vaccine need two doses administered a minimum of four weeks apart for optimal protection. Adults and children ages 9 and older need only one dose. Folks 65 and older can have either a high-dose trivalent or a quadrivalent vaccine, as they choose.

One more thing: After you get your flu shot, ask your doctor what other vaccinations and boosters you and your kids might need. The current reemergence of the measles, which was once thought to be vanquished, is a warning shot. From Jan. 1 to Aug. 29, 1,234 cases have been confirmed in 31 states. Among those folks, 125 were hospitalized and 65 reported having complications, including pneumonia and encephalitis. So get your shots. The sooner the better.

Mehmet Oz, M.D., is host of “The Dr. Oz Show,” and Mike Roizen, M.D., is chief wellness officer and chairman of the Wellness Institute at Cleveland Clinic. Email questions to youdocsdaily@sharecare.com.