Fortunately, most of us can feel confident that we do have measles immunity and that we won’t get caught up in any of the ongoing outbreaks.
Because we are vaccinated and protected!
If you haven’t had two doses of MMR (or any measles containing vaccine since 1967), then understand that two doses is your best protection against measles.
Is There a Blood Test for Measles Immunity?
What about titer tests?
While there is a blood or titer test for measles immunity, it isn’t routinely used.
The one situation in which a measles titer test might be useful though, is for those born before 1957 to confirm that they really had measles.
For others considering a titer test in place of vaccination, it is typically better to just get another dose of MMR, but only if you haven’t already had two doses.
Why Was My Measles Titer Negative?
A positive measles titer does mean that you are immune, but what about a negative measles titer?
“For HCP who have 2 documented doses of MMR vaccine or other acceptable evidence of immunity to measles, serologic testing for immunity is not recommended. 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 (ACIP)
If you have had two doses of MMR and have a negative measles titer, you don’t need another dose of MMR. You are likely immune, even with that negative titer.
“Most vaccinated persons who appear to lose antibody show an anamnestic immune response upon revaccination, indicating that they are probably still immune.”
Epidemiology and Prevention of Vaccine-Preventable Diseases
And since you would need a second dose if you had a negative titer after having just one shot, you might as well just get the second dose instead of checking your titer.
As this infographic describes, it really isn’t that complicated…
What Does Vaccine Shedding Really Mean?
To clear up some things:
yes, some vaccines do actually shed, but it is rarely a reason to avoid getting vaccinated and protected
of the vaccines that we use routinely, shedding is limited to the rotavirus vaccines, FluMist, and the chickenpox vaccines
some other vaccines that can shed include the oral polio vaccine and the smallpox vaccine
the rubella component of MMR may very rarely shed, but only in breastmilk
If vaccines do shed, why shouldn’t we be more concerned about it?
Well, for one thing, most vaccines don’t shed.
DTaP, hepatitis A, hepatitis B, Hib, flu, IPV, HPV, meningococcal, pneumococcal, and Tdap shots – none of them shed.
And then there is the fact that:
when a vaccine sheds, it is the weakened or attenuated vaccine strain, not the wild strain that would cause more serious disease. Putting it another way, if the vaccine strain doesn’t make the person who is getting immunized sick, then why would it get someone else sick if they got it through shedding? Of course, there is a situation in which even a vaccine strain could be dangerous, and that’s for those who are severely immunosuppressed. Still, natural disease would be bad for these kids too!
even with oral polio vaccines, the problem isn’t really shedding, which actually provides a type of passive immunization in areas where polio is still not well controlled. The problem is that very rarely, the attenuated virus in the oral polio vaccine can revert to a form that can cause the person who was vaccinated to actually develop polio (VAPP). Now, shedding of this strain would be a problem, but only if the other person wasn’t immune.
rotavirus vaccines only shed in stool. You can avoid it by washing your hands when you change your child’s diapers, which you hopefully do anyway.
FluMist is attenuated and cold-adapted, which means that it won’t replicate well in our warmer nasal passages and respiratory tracts.
you have to actually get a rash, which is rare, for the chickenpox vaccine to shed.
it is only kids with eczema that usually get sick if they are exposed to someone who recently had the smallpox vaccine. Since the smallpox vaccine causes skin reactions, even the attenuated vaccine strain can cause severe reactions if a child’s skin is already broken down, like with eczema.
Are you still concerned about shedding?
Can a Vaccinated Person Transmit Measles Through Shedding?
To put your mind at ease, understand that you are not going to get measles from shedding.
“In this systematic review, we have determined that there have been no confirmed cases of human-to-human transmission of the measles vaccine virus.”
Greenwood et al on A systematic review of human-to-human transmission of measles vaccine virus
If you aren’t vaccinated and protected, you could easily get it from someone who has measles and who is shedding the wild type virus though. Measles is so contagious, you just have to be in the same room as someone with measles and you will likely get sick. In fact, you can enter a room a few hours after they have left and sill catch measles!
And in theory, if someone developed vaccine-associated measles – they got sick with a vaccine-strain of measles after getting vaccinated – then they could spread the virus to someone who wasn’t immune. That’s just because they would be contagious though, not anything specific to vaccines and shedding. Also, it is basically unheard of for this to happen.
They aren’t even people with measles. Instead, they typically have a vaccine reaction, a rash and/or fever after getting their MMR and they test positive for the vaccine strain of measles because they just got a live virus vaccine.
Is Vaccine Shedding a Threat?
Shedding isn’t the threat that anti-vaccine folks make it out to me.
Think about it. If it really was a big problem, then why don’t more intentionally unvaccinated kids with exemptions get sick when they are around kids who are vaccinated?
“Health officials should require a two-week quarantine of all children and adults who receive vaccinations. This is the minimum amount of time required to prevent transmission of infectious diseases to the rest of the population, including individuals who have been previously vaccinated.”
Sally Fallon Morell, president of the Weston A. Price Foundation
We don’t actually quarantine anyone after they are vaccinated, so why don’t more kids with immune system problems get sick via shedding?
Or just think about what happens in a typical daycare or school. All of the kids don’t get vaccinated on the same day, so if shedding was an issue, wouldn’t the kids who had gotten their vaccines first shed on the ones who weren’t yet vaccinated, getting them sick?
Of course, this doesn’t happen. Again, shedding isn’t the threat that anti-vaccine folks make it out to be.
Do you remember when measles was eliminated in the United States?
You probably should.
It wasn’t that long ago…
When Measles Was Eliminated in the United States
After several years of declining numbers of measles outbreaks in the United States, the endemic spread of measles was declared eliminated in March 2000.
“The data indicated that, during 1997–1999, measles incidence has remained low (<0.5 cases per 1,000,000 population) and that most states and 99% of counties reported no measles cases. In addition, measles surveillance was sensitive enough to consistently detect imported cases, isolated cases, and small outbreaks. Evidence of high population immunity included coverage of >90% with the first dose of measles vaccine in children aged 19–35 months since 1996 and 98% coverage among children entering school. In 48 states and the District of Columbia, a second dose of measles vaccine is required for school entry. A national serosurvey indicated that 93% of persons aged >6 years have antibody to measles.”
So, measles wasn’t gone yet. It was just that most cases were imported from outside the country. Only imported strains of the measles virus were causing outbreaks.
“The end of endemic measles transmission in the United States has both domestic and international importance. Domestically, the absence of endemic exposure to measles means few persons in the United States will be infected and risk complications of measles. This decreased risk of exposure provides protection to groups not protected directly by vaccination: children too young for routine vaccination; the few persons who, although vaccinated, are not protected, primarily from failure to mount an adequate response to vaccine; persons for whom vaccine is contraindicated (e.g., those with immunodeficiency); and persons who choose not to be vaccinated.”
Wharton on Measles Elimination in the United States
Unfortunately, the “choose not to be vaccinated” group might be endagering our claim to have eliminated measles.
“Endemic measles transmission is the existence of any continuous indigenous chain of transmission of measles virus that persists for >1 year in any defined geographic area (e.g., the United States).”
Orenstein on Defining and Assessing Measles Elimination Goals
Still, when you look at the numbers, technically, measles isn’t yet spreading endemically in the United States.
We are getting close though.
The outbreaks in Rockland County and Brooklyn started in September and October 2018. If they aren’t stopped soon, will it be easier to make a case that measles is no longer eliminated in the United States?
“Outbreaks in New York City and Rockland County, New York have continued for nearly 8 months. If these outbreaks continue through summer and fall, the United States may lose its measles elimination status.”
U.S. measles cases in first five months of 2019 surpass total cases per year for past 25 years
It sounds like it.
One thing to consider though, after an unvaccinated visitor introduced measles to Brooklyn from Israel back in October, measles has been reintroduced into the community at least seven other times! This includes travelers from Israel, UK, and Ukraine.
So the outbreak isn’t necessarily a “continuous indigenous chain of transmission of measles virus.”
It is multiple chains in the same community.
“There have been additional cases of measles from international travelers to Rockland, exposing more people to measles.”
2018 – 2019 Measles Outbreak in Rockland County
The same thing has happened in Rockland County after the initial importation from Israel in September.
Measles Elimination Criteria
Does that matter?
It likely should, but let’s also look at how we do with other criteria that are often used to assess the absence of the endemic spread of measles:
Few measles cases/low measles incidence – we will have the most cases in 2019 since 1992, but most cases are clustered in just a few big outbreaks
The duration of outbreaks is short – outbreaks are getting longer and harder to contain, but part of the problem is the global rise in measles and the reintroduction of measles into existing outbreaks
Most cases are associated with international importation – still very true
No endemic measles virus strain – outbreaks this year have been associated with strains that are commonly seen in Ukraine, the Philippines, and a few other areas