Gh0st
Well-known member
https://annals.org/aim/fullarticle/...la-vaccination-autism-nationwide-cohort-study
Study aimed and addressing three areas.
1) MMR vaccine leading to increased risk for developing autism
2) MMR vaccine potentially triggering autism in susceptible individuals
3) Clustering of autism diagnoses chronologically around the time of MMR vaccination
Large cohort study involving 657,461 children in Denmark. Found no support for any of the three points above (no correlation between MMR and autism). Of note, vaccines in Denmark are completely free and voluntary.
Strengths
1) Highest powered study to date assessing correlation between MMR and autism
2) Looked at all births between 1999-2010 in a fairly homogeneous population
3) Data gathered from national registries that have mandatory reporting, eliminating recall bias
4) Considered environmental and familial risk factors to account for any confounding effect
Weakness
Based cases off of time of first autism diagnosis. Symptoms can appear before first diagnosis which can bias in one of two ways.
1) Families may avoid vaccination due to the emergence of symptoms consistent with autism before a diagnosis is made, this would falsely show less vaccine correlation with autism diagnosis because it would show a case of an unvaccinated child developing autism.
2) A child developing symptoms would have more exposure to the health care system in general and is more likely to be vaccinated as a result. This would falsely show a child diagnosed after vaccination even though symptoms were present before ever getting vaccinated.
Study aimed and addressing three areas.
1) MMR vaccine leading to increased risk for developing autism
2) MMR vaccine potentially triggering autism in susceptible individuals
3) Clustering of autism diagnoses chronologically around the time of MMR vaccination
Large cohort study involving 657,461 children in Denmark. Found no support for any of the three points above (no correlation between MMR and autism). Of note, vaccines in Denmark are completely free and voluntary.
Strengths
1) Highest powered study to date assessing correlation between MMR and autism
2) Looked at all births between 1999-2010 in a fairly homogeneous population
3) Data gathered from national registries that have mandatory reporting, eliminating recall bias
4) Considered environmental and familial risk factors to account for any confounding effect
Weakness
Based cases off of time of first autism diagnosis. Symptoms can appear before first diagnosis which can bias in one of two ways.
1) Families may avoid vaccination due to the emergence of symptoms consistent with autism before a diagnosis is made, this would falsely show less vaccine correlation with autism diagnosis because it would show a case of an unvaccinated child developing autism.
2) A child developing symptoms would have more exposure to the health care system in general and is more likely to be vaccinated as a result. This would falsely show a child diagnosed after vaccination even though symptoms were present before ever getting vaccinated.