At back-to-school time, parents dutifully head to the doctor’s office to get their children immunized. But plenty of parents would be wise to roll up their own sleeves.

Too few adults are getting their recommended vaccines, according to the U.S. Centers for Disease Control and Prevention. That’s because many adults don’t know their own immunization history, while others think they’re covered by shots they had in childhood.

Not necessarily, doctors say. Immunity for some diseases wears off over time.

Outbreaks of diseases such as measles and whooping cough in recent years underscore the message that adults who haven’t kept up with their shots are putting themselves — and those around them — at risk.

“Vaccines are pretty much as good a deal as you get in health care,” said Dr. Frank Rhame, a physician at Abbott Northwestern Hospital in Minneapolis. “We’re talking about maximizing health.”

Here are six shots to ask your doctor about:

1. Tdap

This shot protects against tetanus, diphtheria and pertussis (whooping cough). Recommended for adults who didn’t get immunized when they were kids. (There is also the Td vaccine — which is similar but doesn’t protect against whooping cough. Adults should get a Td shot every 10 years.)

“We used to think that whooping cough was only a problem for babies,” explained Dr. Matt Hockett, a physician with Fairview Clinics. “It turns out it’s more common than we realized for adults. It can cause coughing for six to eight weeks.”

For babies, whooping cough can be fatal. That’s why doctors recommend that adults who are around infants get immunized.

2. Shingles

The vaccine protects against shingles, which is marked by a painful rash. “It’s a reactivation of chickenpox that we had when we were kids,” Hockett said.

Half of all shingles cases occur in people over age 60. Because the risk of chronic pain from shingles goes up as a person ages, Hockett recommends his patients don’t put it off and get the single shot as soon as they turn 60.

3. Pneumonia

This lung infection can be serious and even life-threatening, especially for the very young and the very old. Smokers and diabetics also are particularly vulnerable to catching pneumonia.

What once was a single-dose vaccine now comes in two varieties, given at different times. The pneumonia shots — known as PPSV23 and PCV13 — are given to adults on two occasions. The first one is recommended starting at age 65. The second kind is then given about six months to a year later.

4. HPV

Protects against the human papillomavirus, which is tied to genital warts and cervical cancer. Doctors recommend the vaccine for females 11 to 26 years old. It’s also recommended for males ages 11 to 21. “The hope is that by starting it at younger ages, it [HPV] becomes a thing of the past in the future,” Hockett said.

5. Flu

This is the most common vaccine requested by adults. And that’s a good thing, doctors say. The flu vaccine, which can be delivered in a shot or nasal spray for certain ages, is recommended annually for everyone over the age of 6 months.

The vaccine is designed to protect against a handful of strains of flu, but its effectiveness varies from year to year, depending on how well it matches with the particular strains circulating at the time.

6. Chickenpox

If you missed out on this itchy, scratchy disease when you were a kid, it’s best to get vaccinated now. Having chickenpox as an adult, Hockett warns, is a much harsher experience. Symptoms — including blisters, high fever and aches — tend to be worse.

Pregnant women who have not had chickenpox or have not been vaccinated are especially vulnerable.