Concerns over the largest nationwide outbreak of measles in 25 years has prompted the Todd County Health and Human Services to provide straightforward information about the issue:

Am I protected?

The Centers for Disease Control and Prevention (CDC) considers you protected from measles if you have written documentation showing at least one of the following:

• You received two doses of measles-containing vaccine and you are a school-aged child (grades K-12); or an adult who will be in a setting that poses a high risk for measles transmission, including students at post-high school educational institutions; employed as healthcare personnel; or are international travelers.

• You received one dose of measles-containing vaccine, and you are a preschool-aged child; or an adult who will not be in a high-risk setting for measles transmission.

• A laboratory confirmed that you had measles at some point in your life.

• A laboratory confirmed that you are immune to measles.

• You were born before 1957.

Do I ever need a booster?

No. CDC considers people who received two doses of measles vaccine as children according to the U.S. vaccination schedule protected for life, and they do not ever need a booster dose. If you're not sure whether you are fully vaccinated, talk with your doctor.

Killed-measles vaccine

Do people who received the killed-measles vaccine in the 1960s need to be revaccinated with the current, live-measles vaccine?

Yes, people who know they got the killed-measles vaccine (an earlier formulation of measles vaccine that is no longer used) should talk to their doctor about getting revaccinated with the current, live-measles-mumps-rubella (MMR) vaccine.

Not many people fall into this group; the killed vaccine was given to less than 1 million people between 1963 and 1968. Also, most people don't know if they got the killed vaccine during this time.

If you're unsure whether you fall into this group, you could ask your doctor to test your blood to determine whether you're immune. Or you can just get a dose of MMR vaccine. There is no harm in getting another dose of MMR vaccine if you may already be immune to measles (or mumps or rubella).

Does the vaccine work?

The measles vaccine is very effective. Two doses of measles vaccine are about 97 percent effective at preventing measles if exposed to the virus. One dose is about 93 percent effective.

How long does it take?

How long does it take for the measles vaccine to work in your body? For the measles vaccine to work, the body needs time to produce protective antibodies in response to the vaccine. Detectable antibodies generally appear within just a few days after vaccination.

People are usually fully protected after about two or three weeks. If you're traveling internationally, make sure to get up to date on all your MMR shots. You should plan to be fully vaccinated at least two weeks before you depart. If your trip is less than two weeks away and you're not protected against measles, you should still get a dose of MMR vaccine.

How the vaccine works

How does the measles vaccine work? When you get measles vaccine, your immune system makes protective virus-fighting antibodies against the harmless vaccine virus. Measles vaccine protects you from mild-type measles because if you have been vaccinated and then are exposed to someone with measles, your body remembers how to fight off the wild-type virus. That's because the vaccine trained your immune system.

Measles statistics

How common was measles in the United States before the vaccine? Before the measles vaccination program started in 1963, an estimated 3 to 4 million people got measles each year in the United States, of which 500,000 were reported. Among reported cases, 400 to 500 died, 48,000 were hospitalized, and 1,000 developed encephalitis (brain swelling) from measles.

What are the vaccine coverage levels like in the United States? Nationally, the rates of people vaccinated against measles have been very stable since the Vaccines for Children (VFC) program began in 1994. In 2017, the overall national coverage for MMR vaccine among children aged 19 months to 35 months was 92.7 percent. However, MMR vaccine coverage levels continue to vary by state, with 11 states in 2017 having MMR coverage levels of less than 90 percent.

At the county or lower levels, vaccine coverage rates may vary considerably. Pockets of unvaccinated people can exist in states with high vaccination coverage, underscoring considerable measles susceptibility at some local levels.

Why have measles increased?

Some years, states report more measles cases compared with previous post-elimination years. CDC experts attribute this to:

• Measles outbreaks in some countries to which Americans often travel, and therefore more measles cases coming into the U.S.

• More spread of measles in U.S. communities with pockets of unvaccinated people.

Vaccine clinics

Todd County Health and Human Services offers immunization clinics the first Tuesday of each month and the fourth Monday of each month from 9 a.m. to noon, and 1 to 4 p.m. For more information on MMR vaccine or to check on your immunization status, call Todd County Health and Human Services at 320-732-4500.