Measles outbreak: Are all adults protected against the disease?

The increase in the number of measles cases has raised questions about the safety of children, but also of adults. How do you know if you are immune to the disease?

Age can certainly be a factor, according to the Centers for Disease Control and Prevention.

"If we see a substantial increase in the number of measles infections, there will be many more people who will wonder what their immunization status is," said Dr. John Cullen, president of the American Academy of Family. Doctors, told CNN.

The United States has seen 555 cases of measles between January 11 and April 11 this year – "the second highest number of cases reported in the United States since the elimination of measles in 2000," says the CDC.

The CDC guidelines for vaccination against the disease have evolved over the decades. Here are some key points:

▪ Children should receive two doses of MMR vaccine (measles, mumps and rubella), says the CDC. The first vaccine should be given when the child is between 12 and 15 months old and the second between 4 and 6 years old. Two doses are effective at about 97% to prevent the disease.

▪ The two-dose recommendation has been in effect since 1989, says the CDC. Previously, people had received one dose of the vaccine, which is 93% effective in preventing the disease.

▪ People born before 1957 do not need to be vaccinated because most of them have already contracted the disease, according to the CDC.

▪ The inactivated measles vaccine available between 1963 and 1967 was not effective, says the CDC. People who received a vaccine during this period "should be revaccinated".

▪ People should not be vaccinated if they have evidence of immunity to the disease, including documentation of previous vaccination, says the CDC.

▪ If you do not have written documentation on immunity, the CDC recommends that you get vaccinated.

▪ If you do not know if you have received two doses of the vaccine, you can ask a doctor for a reminder, reported NBC News. "There is no harm in being vaccinated at any time," the media said.

"Adults with measles are 10 times more likely to be hospitalized because they are more likely to get pneumonia – one of the complications of the disease," reported NBC News.