The number of measles cases in the United States recently topped 1,000, making it the greatest number of cases in a single year in nearly three decades and the most since the disease was eliminated from this country in 2000.


Measles is so contagious that if one person has it, up to 90% of the people close to that person who are not immune will also become infected.

The worrying comeback of the disease has many Americans wondering whether they need to be vaccinated…again.

Do adults need a booster?

“People who have received two doses of the measles vaccine are protected for life and do not need a booster shot,” said Dr. Kenneth Sands, the chief infectious disease specialist at HCA Healthcare. “Also, anyone born in the states before 1957 is likely immune since the virus was so common back then. And once you’ve had it, you’re not vulnerable again.”

The measles vaccine is a part of a standard vaccination called MMR, or measles, mumps, and rubella. It’s typically administered in multiple doses during childhood with the recommended first dose around 1 year old and the second dose expected between 4 to 6-years-old.

Am I protected?

Two doses of the measles-mumps-rubella vaccine are about 97% effective in preventing the disease, while one dose is still about 93% effective.

Individuals who have only had one dose of the measles vaccine and those in a high-risk setting – healthcare workers, college students, international travelers or people living in a community that’s in the throes of an outbreak – should consider getting a second vaccine, according to Dr. Sands.

“If anyone is unsure of their measles history, and is concerned about contracting the virus, talk to your healthcare provider about getting a dose of MMR,” said Dr. Sands. “With a few exceptions, there is no harm in getting another shot.”

Who should avoid the M.M.R. vaccine?

People who should not receive the vaccine include pregnant women, people with weakened immune systems or those with medical conditions that complicate recommended immunizations including those undergoing chemotherapy treatment, have severe allergies, cancer or HIV, or a family history of immune system problems.

While the science says a majority of people are protected against measles – only about three out of 100 people who get two doses of the MMR vaccine will still get measles if exposed – the unvaccinated population make-up roughly 90% of the measles cases in the U.S.

The bottom line

“Measles is seeing a resurgence due to the spread of misinformation about the recommended vaccinations that are putting the public at risk,” said Dr. Sands. “Parents who are worried about the safety of childhood vaccines should talk to their pediatricians to alleviate any concerns. Getting vaccinated is the safest and most effective way to protect your loved ones from preventable diseases like measles.”

Do you need a booster? Maybe, but not likely.  If you’re not sure that you received two shots, check with your physician. There is a blood test that can confirm your immunity levels.

But the bottom line is this: vaccines save lives.

Visit here for more information about vaccine safety.

Dr. Kenneth E. F. Sands serves as the chief epidemiologist and chief patient safety officer for HCA Healthcare. As a member of the HCA Healthcare Clinical Services Group, he leads enterprise-wide initiatives on health services research, infection prevention, and patient safety.