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CDC Reported that 50% of vaccinated children for measles will still get the measles.... or did they?


Image of measles rash on arm
Image Source: Travel Health Plus

The Physicians for Informed Consent (PIC) on LinkedIn cited a study stating that 50% of children vaccinated for measles still get the disease and can spread it. This is not correct.


The first study cited (2007) is a retrospective study that investigated the duration of measles immunity among children who received the MMR vaccine (1). The study found that some children who received the vaccine lost their immunity to measles over time, and therefore may be at risk of getting measles if exposed to the virus. However, the study did not report a 50% failure rate, and it did not suggest that vaccinated individuals who lose their immunity can spread the disease to others.


The second study cited (2016) is a review of the evidence on measles vaccine effectiveness and safety (2). The review included studies that evaluated vaccine effectiveness in preventing measles, and the authors concluded that the MMR vaccine is highly effective in preventing measles. This study also did not report a 50% failure rate, nor did it suggest that vaccinated individuals who get measles can spread the measles to others.


Other older studies mentioned were from 1989, 1990, for some reason and they do not support their claims.


PIC cited a 2018 Japan study (3) as evidence that "... nearly 50% of schoolchildren and more than 60% of adults fully vaccinated with the MMR vaccine can still be infected with measles virus and spread it to others, even with mild or no symptoms of their own"


While the study provides useful information on the duration of vaccine-induced immunity and the effectiveness of the MMR vaccine against measles variants ('modified measles'), it does not support the claim made by PIC that "50% of children vaccinated for measles still get the measles and can spread it." The study does report some cases of vaccine failure, but the overall proportion of vaccinated individuals who develop measles after being exposed to the virus is much lower than the proportion of unvaccinated individuals who develop the disease. In fact, the reason for the evolution of the modified measles variant is due to reduced vaccination rates (4) and that is likely because of anti-vaccine propaganda (5).


It is important to note that vaccine hesitancy and misinformation can have serious public health consequences, including outbreaks of vaccine-preventable diseases. The MMR vaccine is a safe and effective way to prevent measles, and the overwhelming majority of scientific evidence supports its use (6)*. Vaccination is a critical tool for protecting individuals and communities from infectious diseases, and it is important to rely on credible sources of information when making decisions about vaccination.


References


* This meta-analysis, published in the Cochrane Database of Systematic Reviews in 2018, evaluated the safety and effectiveness of the MMR vaccine in children. The analysis included 138 studies with a total of over 23 million participants and found that the MMR vaccine is highly effective in preventing measles, mumps, rubella, and varicella in children, with high levels of protection against these diseases. The analysis also found that the vaccine has a good safety profile, with no evidence of serious adverse events associated with the vaccine.

Overall, this meta-analysis provides strong evidence to support the safety and effectiveness of the MMR vaccine in children. It is important to rely on credible sources of information when making decisions about vaccination, and the Cochrane Library is a reputable source of evidence-based information on health interventions.

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