Traditionally, the time when measles case counts are the highest occurs:
during the late winter and early spring (temperate climates, like the United States)
after the rainy season (tropical climates)
when kids are in school
So just like flu season, it’s always measles season somewhere…
And in areas of the world where measles is still highly endemic, you can expect cycles of larger measles epidemics every 1 to 4 years.
Can you guess why?
“As higher uniform population immunity is achieved the scale of epidemics, both their duration and absolute number of cases, progressively decreases. Epidemic frequency simultaneously decreases with increasing time intervals between epidemics. Another uniform feature as elimination is approached is the loss of epidemic seasonality.”
Durrheim et al on Measles – The epidemiology of elimination
I’ll give you a hint – there is nothing different about the measles virus during those years.
Eventually though, as the number of people susceptible to measles builds up, there is the opportunity for bigger outbreaks. Of course, that doesn’t happen if most people are vaccinated and protected.
“Source countries included Philippines (14 cases), Ukraine (8), Israel (5), Thailand (3), Vietnam (2), Germany (2), and one importation each from Algeria, France, India, Lithuania, Russia, and the United Kingdom.”
Increase in Measles Cases — United States, January 1–April 26, 2019
In the early part of 2019, we saw a lot of cases because unvaccinated travelers were returning from Philippines, Ukraine, and Israel, countries in peak measles season.
As cases in those countries hopefully slow down over the summer, unfortunately, we might see a rise in other parts of the world.
Of course, there is an easy way to end our measles seasons once and for all.
Get vaccinated and protected, especially before traveling out of the country.
The study they are citing, Rapid Identification of Measles Virus Vaccine Genotype by Real-Time PCR, simply talks about how to “distinguish between measles cases and vaccine reactions.”
“During measles outbreak investigations, rapid detection of measles vaccine reactions is necessary to avoid unnecessary public health interventions.”
Rapid Identification of Measles Virus Vaccine Genotype by Real-Time PCR
While many of these people do test positive for a vaccine strain, they do not actually have measles. They typically just have a rash and/or fever, with a concern that they might have measles because they are in the middle of a measles outbreak.
But if they have a rash and fever and test positive for measles, even if it is a vaccine strain, why shouldn’t we just say that they have measles?
Because measles isn’t just about having a rash and fever. It is having a specific pattern of a high fever for 3 or 4 days, then developing a rash, and continuing to have a fever. People with measles also typically have other symptoms, including irritability, cough, coryza, and conjunctivitis.
Confirmed Case Counts in Measles Outbreaks
Still, since these measles vaccine reactions can get confused with real measles cases, do they inflate the measles case counts in our outbreaks?
While we occasionally do see a “confirmed” case later change as further testing is done, it is important to realize that most cases are thoroughly evaluated to see if they are in fact really measles.
Most case counts are made up of confirmed cases and don’t include suspected cases that might be someone who has a rash after their MMR vaccine or some other viral infection.
“Vaccine‐associated measles is a possible, but extremely rare event.”
Sood et al on Vaccine‐associated measles in an immunocompetent child
Anyway, vaccine induced or vaccine associated measles is extremely rare.
What about the fully vaccinated woman in New York who developed measles, getting four other people sick in 2011?
Didn’t she have vaccine induced measles?
“This is the first report of measles transmission from a twice-vaccinated individual with documented secondary vaccine failure. The clinical presentation and laboratory data of the index patient were typical of measles in a naive individual. “
Rosen et al on Outbreak of Measles Among Persons With Prior Evidence of Immunity, New York City, 2011
She had the D4 strain of measles – not a vaccine strain.
Measles deaths are on the rise too. While the risk of complications of measles can be reduced with vitamin A treatment, that doesn’t eliminate them. And the benefit is mostly in those who are already vitamin A deficient. Vitamin A has a much more modest effect in developed countries, where measles deaths still occur.
What to reduce your child’s risk of dying from measles?
Wait, that couldn’t really happen, could it? Seven vaccinated kids with measles in one family?
How Could Seven of My Vaccinated Kids Have the Measles Right Now?
While anything is possible, this story is very improbable once you look at the details…
“When her 12-year-old son spiked a fever and started complaining of a sore throat right before Passover, Mrs. Pearl (not her real name) wasn’t worried. She confidently crossed off a host of possible infections that he was fully vaccinated for.
She thought he had strep throat, like two of his siblings.
They headed to urgent care for a rapid strep test, but the result was negative. Undeterred, she put her son on antibiotics at the nurse’s recommendation, and sent her son to bed.
He’d worsened by morning.
He woke feeling feverish and broken out in a rash.”
Could that be measles?
He ended up testing positive for measles, even though he was fully vaccinated. Only two days of fever before he developed his rash though, and no word that the fever continued, as you would expect with measles…
“Not long after, Mrs. Pearl’s 10-year-old broke out in a similar rash.
This child didn’t spike a fever but his breathing was labored and he complained that his eyes hurt.
He also tested positive for the measles.”
Although they all could have been exposed to someone else, it is important to note that the incubation period for measles is 7 to 14 days. The “not long after” scenario sounds like too short a time to get “measles” from his brother. Also, no fever, which would be very strange for measles…
But the other five kids had more classic symptoms of measles, right?
“Of the seven other children that Mrs. Pearl had tested—all of whom had been fully vaccinated—five more showed no immunity to measles.”
That’s actually not unusual after measles vaccination. It’s not proof or any kind of indication that the vaccine didn’t work. It has been long known that most vaccinated people who have negative measles titers will show an anamnestic immune response if they get another dose of MMR.
What does that mean? It means that they were likely immune, even with the negative titer.
“In the event that a HCP who has 2 documented doses of MMR vaccine is tested serologically and determined to have negative or equivocal measles titer results, it is not recommended that the person receive an additional dose of MMR vaccine. Such persons should be considered to have presumptive evidence of measles immunity. Documented age-appropriate vaccination supersedes the results of subsequent serologic testing.”
Immunization of Health-Care Personnel: Recommendations of the Advisory Committee on Immunization Practices
In fact, we don’t routinely check titers after MMR, at least not for measles.
And their symptoms?
“Two hours after getting the MMR booster, Mrs. Pearl’s 16-year-old spiked a 102-degree fever and broke out in a measles rash.
Four days later her three other children, all of whom had received the MMR booster, all had measles rashes, canker sores in their mouths, gastrointestinal problems, and lethargy.”
Canker sores with measles? Kids with measles get Koplik spots, but no one describes them as canker sores.
Fever and a rash developing at the same time?
Yeah, none of that sounds like measles. At all.
Remember, the classic symptoms of measles include 3 to 5 days of a high fever with cough, coryza, and conjunctivitis, followed by a rash, with continued fever.
“According to Mrs. Pearl, the health department official also told her that measles vaccine failure is common and that about half the people getting measles in the current measles clusters in Brooklyn are fully vaccinated.”
Actually, only 27 of the 566 people in Brooklyn with measles have been known to be fully vaccinated, with two doses of MMR. How much less than half is that? It is less than 5% of cases.
Why Did They Say That Seven of My Vaccinated Kids Have Measles?
So how do you explain what happened to this family?
Besides the likelihood that they had another, more common virus causing their symptoms? With mouth ulcers and diarrhea, like maybe Coxsackie virus?
Do you really need another explanation?
How do you explain the positive measles tests?
They were almost certainly a false positive.
“The test kits in use have been shown to have high sensitivity and specificity. However, cross-reactions with other viral diseases, e.g. rubella and Parvovirus, may occur.”
Dietz et al on The laboratory confirmation of suspected measles cases in settings of low measles transmission: conclusions from the experience in the Americas.
They didn’t state which test was done, but it is important to note that several are available. This includes an immunoglobulin test, PCR from a throat swab, and PCR from a urine specimen. The most accurate testing is done by the CDC.
“Detection of specific IgM antibodies in a serum sample collected within the first few days of rash onset can provide presumptive evidence of a current or recent measles virus infection. However, because no assay is 100% specific, serologic testing of non-measles cases using any assay will occasionally produce false positive IgM results.”
Serologic Testing for Measles in Low Prevalence Setting
Did they have confirmatory tests, after their initial positive test? Were they done at a state lab? Did all of her other kids test positive for measles?
“She’s angry at the measles vaccine failure and worried about her family members, especially her pregnant daughter.”
“I used to think people who don’t vaccinate were crazy,” Mrs. Pearl says. “Now I’m not so sure. Maybe they’re right. Maybe my body doesn’t want to take garbage. Something is a red flag. After my story, I’m not so sure where the measles started. I’m legit. I did vaccinate. All my kids are up to date. Children ages 22 to 7 all getting the measles?”
Something is indeed a red flag. To get to the bottom of it, Mrs. Pearl should revisit the idea that her kids really had measles.