Most everyone in the United States now knows that the nation is suffering from one of its largest outbreaks of measles, in fact the largest since we achieved nearly total control of the infection in 2000. As of a few days ago, over 700 cases of measles have appeared in 22 states. So far, through May 2, 2019, there have been no reported cases of measles in Ohio.
Some Measles Basics
Measles is at once a very familiar word and a very unfamiliar disease.
It is a familiar word because essentially every human had measles until the vaccine for measles was first put to use in 1963. Interestingly, the measles vaccine was first developed from a strain of virus first able to be grown in a lab by Drs. Enders and Peebles at Boston Children’s Hospital. Dr. Enders was the same doctor who was one of a team of three to first learn to grow polio virus in the lab, one of the other three was the beloved Dr. Fred Robbins who was a giant in infectious disease work here at Case Medical School for many, many years.
We all know the drama of Jonas Salk’s application of the techniques of Dr. Enders used to mass manufacture the first polio vaccine, and how the terror of families, the specter of polio, was vanquished by this vaccine. The danger of polio remains in our minds to this day.
For some reason, measles seems like a far milder problem. It is likely because many children with measles recovered without harm, but even so, even today, 1 in 1000 children who get infected with measles still die from it. About 37,000 people have come down with measles in Europe in the past many months, and about 37 have died, proving the reality of this number.
Measles can also cause a terribly severe level of permanent brain damage. It is a disease to be avoided. Which is why science worked so hard in the 1950’s to develop a vaccine that would do for measles what the polio vaccine did to polio.
Measles is also known for being extremely contagious. If a person with measles walks in a room with 100 people who can catch it, 90 of them will catch it with that one exposure!
Measles vaccine is only available in a 3 or 4-disease combination vaccine- the Measles-Mumps-Rubella vaccine, known to all as the MMR, or the MMR plus chickenpox (Varicella) vaccine, or the MMRV.
The MMR is a live vaccine, so if you get one dose and it works, you will be immune to measles for many, many years, likely your entire life.
The most recent data from the CDC finds that for anyone age 12 months or older who gets only one MMR vaccine, the chance of it working is 93%.
The same data from the CDC find that for anyone age 12 months or older who gets one MMR, then a second dose at least 1 month later, the chance of it working is 97%.
By working, we mean that if you stand in a room with active measles virus, you will not get sick.
Even those for whom the MMR does not work, 7% of one dose and 3% of two dose people, and who might get measles if exposed, the disease is far milder and the chance of dying from measles or suffering permanent brain injury is dramatically reduced.
Now, It’s All About Timing
Right now, Advanced Pediatrics is getting many calls and visits with a very high level of worry, and for good reason. The measles epidemic is upon us in America, not yet in Ohio, but no one knows how long that will remain so. And the epidemic is unusual because it is man-made. Measles was close to elimination in America in 2000, it returns to our communities now mainly by the choice of many to not immunize. Some of the measles outbreak comes from international sources from places that have poor immunization infrastructure, or vaccine delivery infrastructure interrupted by war, but many cases in the US are happening because of the choice of many to not let their children get the protection. We now know the answer to a key question: what would the world look like if everyone got immunized, and what would the world look like if no one got immunized? With immunizations, diseases the immunizations prevent cease to be part of our lives. Without immunizations, once vanquished dangers rise up to infect us all over again. The experiment is being done right now, take away immunization protections, and we stand at risk of dangerous disease.
And so, with measles cases rising, the question for many is, how do I protect my child, how do I protect people my age, and older?
The Ages to Immunize Children
12 months old
The first answer is easy, 12 months and up. Every child healthy enough to be immunized, should get an MMR as close to their first birthday as possible and then 1-3 months afterwards. That is the surest way to secure 97% chance of lifetime protection. Any child who has had two doses of MMR after their first birthday, and at least 1 month apart is as safe as anyone can be from catching a serious case of measles, and no further testing or immunization is indicated or at all helpful.
Under 12 months old
The problem with giving a baby MMR before a year of age is that mothers who have had measles or the MMR give their baby measles antibody that will keep them from getting measles. That’s a good thing, right? Yes. But, if that maternal antibody to measles is present, if we give the MMR, Mom’s antibody wipes out the measles vaccine virus, and the MMR will have no impact on measles immunity.
Now, here is where it gets complicated. As soon as the umbilical cord is cut, the Mom’s antibody to measles in the baby stops flowing into the baby, and the baby’s measles antibody begins to drop. By one year of age, there is no more maternal protection to measles, and that is why the MMR is not given until then.
At a time when there is no measles around, it makes sense to give the first dose of MMR at age one, after all, by then it can work in everyone. Give it earlier, and some babies will still have Mom’s measles antibody and the MMR won’t work.
But the number of babies with protection from Mom’s measles antibody drops gradually from birth to one year. One study from Israel (https://www.ncbi.nlm.nih.gov/pubmed/8584363) found that by 4 months old, about 50% of babies had protective Mom’s antibody to measles and by 6 months old that number has dropped to 30%.
So, again, if there is no measles epidemic, it makes sense to give the first MMR after turning one, no risk of measles around, and 100% chance the MMR will not be neutralized by Mom’s antibody to measles.
But in the midst of a measles epidemic, what about those infants who lose Mom’s antibody to measles before their first birthday? The closer to one year of age, the more the early MMR makes sense. The closer to birth, the less sense it makes, all related to the level of Mom’s antibody to measles which declines after birth.
The CDC has set the following guidance to seek a reasonable balance here:
- If no measles is around, wait to the first birthday to give an MMR
- If measles is around, it starts making sense to give the first MMR by age 6 months, but not earlier.
- If the MMR is given prior to the first birthday, it does not count as one of the two doses all kids should get, because the one given prior to 12 months old might be neutralized by Mom’s antibody to measles.
The current MMR is the one that leaves all with a 93% chance of being protected after one dose and a 97% after two doses. This form began being used in 1968.
There was no measles vaccine available prior to 1963.
Many measles vaccines from 1963-1968 were of questionable efficacy
On any given day, any adult can get a blood test to see if they have protective antibody to measles from prior vaccination.
These facts lead to the current recommendations:
- Anyone born before 1957 is almost certainly going to have had measles and does not need an MMR
- Anyone born in 1957 and since who has had at least one MMR should be fine, no further action necessary, especially if the MMR was given after 1967.
- Anyone born at anytime who knows and can prove they had measles does not need an MMR
- If you are not sure, you have two options:
- Get a blood test, and if it is negative for antibody to measles, get an MMR
- Skip the blood test and get an MMR
If you are an adult and determine you need an MMR, one dose will work 93% of the time, and two doses 97% of the time. One helps a lot, two is required in most populations to stop epidemics.
- Measles is very, very contagious, and can be deadly. Immunization works, when nations use it, measles ceases. When nations don’t use it, measles comes roaring back.
- If you don’t live near cases of measles, wait to age 12 months to get your 2 doses of MMR, at least one month apart.
- If you are an infant in an epidemic area, get an MMR if 6 months or older, it will not count as one of your 2 doses after age 1 year. Most infants are protected under age 6 months by their Mom’s antibody to measles.
- If you are an adult in an epidemic area, check the guidelines above.
Measles is back, we can get rid of it by getting our national rates of immunization for measles back up, meantime, stay tuned to see if and when it reappears here in Ohio.
To your health,
Dr. Arthur Lavin