It’s that time again … flu season is on the way. Vaccines already are available in most locations, so we have no excuse not to get a flu shot soon.

Sometimes the dilemma can be deciding which shot to get. Most flu vaccines contain protection from three strains of influenza, called trivalent vaccines. Those contain two A strains and one B strain of influenza.

Some of them add coverage for a fourth strain. Those shots are called

quadrivalent and contain two A and two B strains. With two Bs, the Centers for Disease Control and Prevention doesn’t have to flip a coin to decide between two equal B vaccines; it can just include both.

In addition, there are high-dose flu shots especially for seniors age 65 and older. As we age, our immune systems don’t respond the same way, and a regular flu shot might not get us the strong immune response we need to avoid the flu.

The strains change every year, which is why most people need to “renew” their flu vaccine each year. The CDC tracks which influenza hits, and when, in making its calculations for the following year. For the 2016-2017 season, it calculated that those who received flu shots reduced their overall risk by 34 percent for A strains and 56 percent for B strains.

Your best (safest) bet: Ask your doctor which flu shot you should get. Some of us under 65 shouldn’t have the high-dose shot for one medical reason or another. Don’t delay; it takes about two weeks to have immune coverage after receiving a shot.

If you have Medicare Part B, the cost of the shot is covered, as well as the vaccine for pneumonia and hepatitis B.

© 2017 King Features Synd., Inc.