2Cemts, the study you cite claiming to prove No MMR-Autism Connection was DEBUNKED: see below:
“No effect of MMR withdrawal on the incidence of autism: a total population study”[17]
Authors: Hideo Honda, Yasuo Shimizu, and Michael Rutter,
Publication & Date: Journal of Child Psychology and Psychiatry. June, 2005.
Details: The authors studied cumulative incidence of ASD up to age seven for children born from 1988 to 1996 in Kohoku Ward, Yokohama, Japan. Japan is unique, because MMR was introduced in 1989 and discontinued in April 1993. ASD cases included all cases of pervasive developmental disorders according to ICD-10 guidelines.
Results: MMR coverage dropped considerably in Yokohama in the birth cohorts of 1988 through 1992, (because of safety concerns over the strain of live mumps virus being used), and not a single MMR vaccine was administered in 1993 or thereafter. “In contrast, cumulative incidence of ASD up to age seven increased significantly in the birth cohorts of years 1988 through 1996 and most notably rose dramatically beginning with the birth cohort of 1993.”
Authors’ Conclusions: “The significance of this finding is that MMR vaccination is most unlikely to be a main cause of ASD, that it cannot explain the rise over time in the incidence of ASD, and that withdrawal of MMR in countries where it is still being used cannot be expected to lead to a reduction in the incidence of ASD.”
CRITIQUES OF THE STUDY[18]
■ The study tells us little about ASD incidence of ASD prior to 1988, when MMR was introduced. But we do know that the published prevalence of ASD did not exceed 25-per-10,000 at any time in Japan prior to 1988.
■ Annual incidence of ASDs for children born in 1987 was 20-per-10,000, but after MMR was introduced, in 1988, annual incidence more than quadrupled, to 85.9-per-10,000 for children born in 1990.
■ But then, MMR coverage began to decline dramatically, as concerns over the mumps viral component grew. ASD incidence likewise declined during this period, to 55.8 for children born in 1991 – representing a drop of 35%.
■ Following complete discontinuation of MMR in 1993, ASD incidence rose again, this time quite dramatically, to 161-per-10,000 for children born in 1994. However, during this time the recommended schedule was changed to include three single vaccines (M-M-R, given four weeks apart), which gained widespread acceptance, causing coverage to increase significantly.
■ For all practical purposes, children vaccinated according to the new schedule were still receiving ‘M-M-R’ at around age one. Giving the three separate vaccines in such close proximity amounts to overlapping exposure, in biological terms.
■ Early MMR trials showed clear evidence of ‘interference’ between the viruses in the combined vaccine, mediated through an altered immune response. The safety consequences of this ‘interference’ are completely unknown.
■ Children who have natural measles (or single measles vaccine) and natural mumps infections within the same year are at significantly greater risk of later inflammatory bowel disease,[19] which is consistent with an ‘interference’ phenomenon that could increase the risk of long-term measles virus infection and delayed disease.
■ The authors are wrong to examine MMR as the single exposure of interest, when in biological terms, exposure to M-M-R through three consecutive monovalent vaccines actually increased after 1993 when MMR was discontinued.
■ The data, therefore, could be interpreted as indicating a major influence of the pattern of exposure to these vaccine viruses on ASD incidence in this Japanese population.
■ More importantly, the data suggest a possible re-challenge effect of close temporal exposure to these three vaccine viruses on ASD incidence at the population level, whereby the exposure (MMR) has been introduced, removed (voluntarily through lack of public confidence), and then re-introduced (as M, M, and R close together).
■ ASD numbers increased and decreased in direct proportion to the total number of children vaccinated with the three live viruses. There is evidence of an effect not only from de-challenges and re-challenges, but there is also a “dose-response” relationship on a population level.
■ Such a dose-response relationship on a population level is rare; and is evidence of a possible causal association.
■ The interpretation by Public Health officials that this is the “last word on the subject” and that these data prove that MMR is safe is misleading and suggests a very limited perspective of the issues and a misunderstanding of published concerns on viral interference in a trivalent live-virus vaccine.
Undisclosed Conflict of Interest: Co-author Michael Rutter has close associations with the drug industry, including GlaxoSmithKline. He was a paid expert witness on their behalf in the UK MMR vaccine damage litigation. That was not declared in the Honda/Rutter paper.
SUMMARY:
Despite the methodological problems in Honda et al., and quite apart from the fact that an ecological study of this kind cannot be used to make attributions about causality, the unrecognized challenge-rechallenge effect of vaccination on autism rates in Japan provide yet another piece of support for the MMR-autism link. Because this study failed to clearly interpret the true population risk in the exposure of interest–assuming the removal of an exposure that in reality had remained– the conclusions drawn by the authors are based on erroneous reasoning. Although drawing overly strong conclusions about an association between MMR-type exposures and autism would be premature in light of the study’s ecological design constraints, the data clearly indicate that further scrutiny of the data is required