Should adults get a booster shot of measles and other childhood vaccines?

In Texas, at least 90 cases of measles have been reported in recent weeks across the northwest part of that state. Among those cases are five people who say they’ve been vaccinated.

It’s not known whether those five cases were fully vaccinated. Whether you’re watching this unfold from Texas or elsewhere, you might be wondering: Should you look into getting a booster shot for measles or other infectious diseases?

For measles, the short answer is no, said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center.

“The measles vaccine is one of our most extraordinarily successful vaccines,” said Schaffner, who was formerly the medical director of the National Foundation for Infectious Diseases. “If you’ve been appropriately vaccinated in childhood, you don’t have to worry about [getting a booster].”

That said, he added, “all vaccines are not identical. Some are better than others.” The protective elements of a few routine childhood vaccinations wane over time, which means boosters are recommended for all adults; for some adults with certain ailments or life circumstances, other boosters may be recommended.

Below, infectious disease experts tell NBC News when and why some adults might need boosters of certain routine childhood vaccinations.

Measles

Most vaccinated adults don’t need a booster for measles.

Since 1989, U.S. advisory committees have recommended two doses of the measles, mumps and rubella (MMR) vaccine for all children. The first dose is usually given to babies between 12 and 15 months, and the second between ages 4 and 6.

“And if you do that — you’re set,” Schaffner said. “For life.”

If you were born before 1957, you most likely were exposed to measles as a child and have natural immunity. In that case, no vaccination or booster is needed, said Dr. Priya Sampathkumar, an infectious disease specialist at the Mayo Clinic. Additionally, if you were born after 1957 and you have access to your vaccine records showing you got both doses, you’re all set, Sampathkumar said.

Even one dose offers sufficient protection for most adults, according to the Centers for Disease Control and Prevention.

“The problem is many of us … don’t know for sure if we received vaccines or not — and we have no one to ask,” Sampathkumar said. By the 1970s and ’80s, most schools had regulations requiring vaccines, she said, so that offers a clue.

In an outbreak, however, the recommendations may change for some people.

If you know you received both doses of the MMR vaccine, there are no recommendations for a third dose — even in an outbreak, according to the CDC. If you know you only received one dose, the CDC recommends listening to your local public health department, which may recommend a second dose for adults.

“The bottom line is, if you don’t know and you live in areas where measles is spreading, then you could consider getting vaccinated,” Sampathkumar said.

For some people in special circumstances — hospital workers in high-risk settings, people who are or live with someone who is immunocompromised, or organ transplant candidates — it may make sense to take a titer test, which measures the level of antibodies in your blood. “They may check your titer levels at that point and you may need revaccination,” said Dr. Michael Aguilar, who practices family medicine in Akron, Ohio, and is affiliated with the Cleveland Clinic.

But what about those five people in Texas — the ones who say they were vaccinated and yet contracted measles anyway?

Breakthrough cases can occur, but “it’s pretty rare,” said Dr. Ryan Maves, an infectious disease expert at Wake Forest University School of Medicine. These cases tend to be milder, with a faster recovery time and a lower risk for severe complications like pneumonia as compared to cases of measles in unvaccinated people, Maves said.

Measles is especially worrisome to public health experts, Maves said, because it can cause what’s been called “immune amnesia.”

“The protection you have from prior infections can often be eliminated by measles affecting your B cells, the type of white blood cells that are involved in the production of immunologic memory — antibodies to the things you’ve been exposed to before, like chickenpox, for example,” Maves said.

“It can actually wipe out your immunologic memory,” he said.

Tetanus

Most adults should get a tetanus booster every 10 years, Maves said.

The vaccine for tetanus is included in a combination vaccine that also protects against diphtheria and pertussis (more commonly known as whooping cough). The shot for young children is called DTaP, and the shot for older kids and adults is called Tdap. (Tdap contains fewer diphtheria and pertussis proteins than DTaP.)

“You get your primary series when you’re little little,” Aguilar said.

Current recommendations are for five doses of DTaP throughout childhood, at 2 months, 4 months, 6 months, 15 months and 4 to 6 years old. The Tdap vaccine is recommended for preteens (ages 11 to 12), and every 10 years after that.

“Obviously, the tetanus part is in case we are injured — we have a puncture wound, we step on a nail,” Maves said.

Tetanus is a potentially deadly bacterial infection that can enter the body through a scrape or cut and causes severe, painful muscle spasms, including in the neck and jaw, which is why it’s commonly called lockjaw.

But, again, it’s not always so easy to keep track of your vaccination records as an adult. “If an adult needs a tetanus booster, and we don’t know if they’ve had a Tdap, it’s totally safe and reasonable to give them a booster,” Aguilar said.

Pertussis (whooping cough)

Like the tetanus shot — because they’re part of the same combination vaccine — the current recommendation for adults is to get a pertussis booster every 10 years.

Whooping cough is a very contagious disease, spreading easily when an infected person coughs or sneezes, and rates of the respiratory illness have increased in recent decades, according to the CDC.

That’s in part because of lower vaccination rates, Maves said. Keeping up with your booster for whooping cough is especially important, because the protection wanes over time, infectious disease experts say.

This wasn’t always the case. In 1991, the diphtheria-tetanus-acellular pertussis (DTaP) vaccine was licensed in the United States. But until the 1990s, whole-cell pertussis vaccines were administered. “That means they took the entire pertussis cell and killed it — but you’re still getting all the parts of that bacterial cell,” Maves explained. The acellular pertussis vaccine, in contrast, does not contain whole bacterial cells; instead, it has proteins that trigger an immune response, he said.

The whole-cell vaccine lasted longer, but it also had more side effects, like high fevers. “Kids would feel kind of blah afterwards,” Maves said. “High fevers were not unusual at the time, and in really little kids, high fevers attract a lot of attention, and in rare cases can provoke seizures.”

The acellular vaccine is still an effective vaccine. “It doesn’t cause those side effects, but it also doesn’t last as long,” Maves said. “That’s kind of the trade-off.”

If you know someone who’s had a baby recently, they may have asked you to get a Tdap booster. That’s because newborns are most at risk for pertussis. Pregnant women are given boosters for Tdap at around 27 to 36 weeks to protect their babies from whooping cough until the infants can get their own shot at two months.

“It’s recommended that not only mother and father and all the children in the family be vaccinated, but anyone — Aunt Susie, grandparents, the neighbor down the street — who wants to come in and see the new baby and get close, that they shouldn’t be allowed in the house unless they’re updated with their Tdap,” Schaffner said. By “updated,” he means within the last 10 years, but ideally within the last five.

Meningitis

Most adults do not need a booster for meningitis. But there are exceptions, experts say.

Most people should get their first meningitis shot at 11 or 12, and a second at 16, according to CDC recommendations. “We vaccinate people against meningitis in adolescence in anticipation of college or the military,” Maves said. “Really, where [the disease] spreads is in congregate settings — college dorms, military barracks, places like that.”

Protection from the vaccine lasts around five years, Maves added, and so a booster is not typically needed. “By the time that vaccine is worn off, you’re out of that risk period,” he said. You’ve likely graduated from college or have moved out of the dorms, in other words.

Certain adults may need a booster, however, Maves said. The spleen is an important organ for fighting meningitis, and so people with lymphoma or sickle cell disease may need a booster. Same goes for someone who is living without a spleen due to a traumatic injury like a car accident. People with diseases that affect their immune system, such as HIV, may also require boosters.

Someone traveling to the so-called “meningitis belt” of sub-Saharan Africa, which routinely experiences epidemics of the disease, will also need a booster shot before they go, Aguilar added.

HPV

There is no data to support the need for an HPV booster shot for adults, Maves said.

The CDC recommends two doses for most people, with the first shot given before they turn 15 and the second given six to 12 months after that. It protects against nine strains of human papillomavirus, which is the leading cause of cervical cancer.

“It actually prevents cancer, which is pretty cool,” Aguilar said. The HPV vaccine was first recommended in 2006 for adolescent girls. A recent study showed a sharp drop in cervical cancer mortality among women younger than 25 — the first age group to be widely vaccinated against HPV.

“Even though the real attention is on cervical cancer, HPV causes head and neck cancer,” Maves said. “It could cause male genital cancers, it can cause anal cancer. So although the highest-risk group are certainly women … it broadly benefits everyone.”

But what if you’re too old to have gotten the HPV vaccine at all?

There is no recommendation for adults older than 26, though adults up to age 46 can discuss with their health care provider whether it makes sense for them to get the shot. The vaccine is most effective before you’re exposed to HPV, a common sexually transmitted infection. Most sexually active adults will have been exposed to HPV, according to the CDC.

“If you didn’t get it as a kid and you’re in your 30s or 40s, it is reasonable to at least consider getting [the HPV vaccine] as catch-up,” Maves said. “It’s hard to prove any benefit once you’re past your 40s.”

This article was originally published on NBCNews.com