The current measles outbreak in the United States has highlighted the dangers of skipped vaccinations, and some people may be wondering whether it's too late to get vaccinated now.
The answer is no.
If an adult or child had not received the MMR [measles, mumps and rubella] vaccine, "it's not too late," said Dr. Ambreen Khalil, an infectious-disease specialist at Staten Island University Hospital in New York City.
So, what if you don't know if you received the shot? "It is better to get an MMR vaccine again, if one does not remember," Khalil added. [ Measles Outbreak, Measles Vaccine: Top Questions Answered ]
The current U.S. measles outbreak has infected at least 102 people in 14 states, and is thought to result at least in part from some people not being vaccinated against the disease.
Who should get vaccinated?
The Centers for Disease Control and Prevention (CDC) recommends that adults who were born after 1956 get at least one dose of the vaccine, unless they can show that they have either been vaccinated or had all three diseases that the MMR vaccine protects against. Those born before 1957 are assumed to have had measles, which confers lifelong immunity.
Children should get two doses of the vaccine: the first one at 12 to 15 months of age, and the second one when they are between 4 and 6 years old. The second dose can be given earlier, as long as it is at least 28 days after the first dose. More than 95 percent of people who receive a single dose of MMR will develop immunity to all three viruses, according to the CDC.
Children who are older than the CDC's recommended ages for vaccination and have not received their shots should get vaccinated, said Dr. Jennifer Lighter-Fisher, a pediatric infectious-disease specialist at NYU Langone Medical Center in New York City.
In fact, even if you're exposed to someone who currently has measles, if you get vaccinated within three days of being exposed, you could be protected, Lighter-Fisher told Live Science.
The only people who should not get the MMR vaccine are infants younger than 12 months, pregnant women, people with compromised immune systems (such as those who have cancer or AIDS), or those who are allergic to the vaccine, she said.
Why get vaccinated?
Vaccination is important because it protects not only the individual but also people within the community who can't be vaccinated for those health reasons. When people choose to not be vaccinated, they're putting infants and those who are too ill to get the vaccine at risk, Lighter-Fisher said.
The MMR vaccine is "absolutely safe," and has been given to millions of people around the world, Lighter-Fisher said. "There's no association with autism ; it has been studied in hundreds of thousands of people."
In fewer than one in 1 million cases, the vaccine can cause a severe allergic reaction. More common reactions include fever, a mild rash or swelling of glands in the cheek or neck, according to the CDC.
But contracting measles can be far worse.
"Before the vaccine, there were 2.6 million deaths per year caused by measles" worldwide, Lighter-Fisher said. "In 2013, there were 146,000 deaths globally," from measles, or about 440 deaths per day, she added.
Last year's Ebola epidemic got an enormous amount of media attention, but the chances of getting Ebola are extremely rare. "Ebola's like a shark bite," Lighter-Fisher said. By contrast, measles is "extremely contagious," yet entirely preventable.
"No one has to have measles," she said.