Why do some parents think that measles protection from the MMR vaccine might wane over time?
Yup – misinformation from the usual suspects.
Does Measles Protection from the MMR Vaccine Wane Over Time?
Wait, how can this be misinformation if they are citing a source and it is a study published by the CDC?
“The results, published in Archives of Pediatrics and Adolescent Medicine, show that even after being previously vaccinated twice for measles, about 35% of vaccinated 7-year-olds and 60% of vaccinated 15-year-olds are susceptible to subclinical infection with measles virus.”Physicians for Informed Consent: CDC Data Shows Immunity from the MMR Vaccine Wanes Over Time
While that doesn’t sound good, that’s not what the study really says!
“A rise in the proportion of persons with low antibody levels suggests an increase in potential susceptibility, but low titers are unlikely to represent the same risk of illness or viral transmission as absent antibodies.”LeBaron et al on Persistence of Measles Antibodies After 2 Doses of Measles Vaccine in a Postelimination Environment
They are clearly misinterpreting what the study does say and mean.
“In summary, we found that, in a population of children who had received 2 doses of measles vaccine at ages and intervals consistent with US policy and who were unlikely to have been exposed to wild-type measles, potential susceptibility rates were low for as long as 10 years after the second dose.”LeBaron et al on Persistence of Measles Antibodies After 2 Doses of Measles Vaccine in a Postelimination Environment
The funny thing is that the study is about what happens to vaccine induced immunity in the absence of exogenous boosting.
In other words, what happens when vaccines get diseases under good control so that we are no longer exposed to wild disease which can give our antibody levels a little boost.
So they are highlighting a study that proves that vaccines work and fortunately, it concludes that “measles antibody persists,” even without exogenous boosting.
The other study they cite discusses a measles outbreak in Japan.
In the 2018 outbreak, 99 people got measles.
“A recent outbreak of measles in Okinawa Prefecture, Japan ended with 33 measles cases whose symptoms were masked because of insufficient protection against the disease (modified measles).”Mizumoto et al on Transmission potential of modified measles during an outbreak, Japan, March‒May 2018
Only 10 were fully vaccinated with two doses of measles vaccine. An additional 20 had one dose.
“Symptoms in modified measles cases are masked, so they do not present with the full (typical) symptoms of measles (fever, maculo-papular rash and catarrhal symptoms such as cough, coryza or conjunctivitis) and their transmission risk is reported to be lower.”Mizumoto et al on Transmission potential of modified measles during an outbreak, Japan, March‒May 2018
While many vaccines do lead to milder disease, even if the vaccine doesn’t provide full protection, we don’t typically see that with measles, except for rare case reports.
So instead of modified measles, it is possible that many of these folks were simply very recently vaccinated, likely in response to the outbreak, and were having a vaccine reaction.
Remember, measles containing vaccines do commonly cause a fever and rash as a side effect. That’s why we sometimes see vaccine strain measles in outbreak reports. These aren’t typically people with measles or modified measles.
“This case report adds further evidence for lower infectivity of modified measles with no secondary cases and highlights the potential requirement for updated contact tracing recommendations in this scenario. Other case reports have shown that individuals with modified measles and history of prior vaccination have more robust levels of plaque reduction neutralisation (PRN) titre, reflecting an immunity booster response. These case studies also identified no secondary cases. In measles outbreak reports in healthcare workers with two documented MMR vaccines, no onward transmission of measles has been reported.”Uren et al on Modified measles with an atypical presentation
Still, although it would be better if vaccines prevented disease and you would get sick at all, when they don’t, isn’t a modified case better than getting full blown measles?
And the bottom line is that the so-called Physicians for Informed Consent is once again misleading people if they are trying to make them think that the MMR vaccine will wane and that “Nearly 50% of Vaccinated U.S. Schoolchildren Can Become Infected With and Spread Measles.”
The only school where you will find that nearly 50% of the kids are susceptible to measles is likely a Waldorf school. But that’s only because they won’t be vaccinated and protected.
More on Waning Immunity