Autism & MMR before Wakefield

Post #853

In my original report, it was discovered that there was a new case of autism for every 169 doses of MMR vaccine given out. That report had sparse data, but it used the time-point of the 1998 publication by Wakefield et al. (that had suggested a temporal link between autism and MMR) — to take advantage of the variation in uptake/coverage.

When MMR uptake was high, autism was high. When MMR uptake lowered, autism lowered. When MMR uptake was high again, autism was high again. Using both autism and autistic spectrum disorder (ASD) as search terms, here are the VAERS reports in the USA for the 7 years prior to 1998:

The number of ASD reports for MMR vaccine was already rising before 1998, when Andrew Wakefield published the original report in The Lancet. Here is the reporting rate per million net doses distributed:

Again, you can see that the rate was rising prior to the 1998 Wakefield publication. The reporting rate falls after 1998, dropping down to 3.3 ASD reports per million doses by 2001, but that’s still 3 times higher than it had been back in 1991. Here is the percentage share of all adverse event reports for MMR vaccine involving ASD:

By examining “the share of all reports” related to a particular adverse event, you can get information regarding “disproportionality” — although the typical test for a safety signal is to compare the share of all reports a particular adverse event comprises for the target vaccine to the share of all reports that it comprises for all vaccines.

Evidence suggests that the proportion of all adverse event reports for MMR vaccine which involved ASD grew 6-fold from 1991 to 1998. But here is how you’d find a proportional reporting ratio (PRR), which is something that CDC uses in order to detect safety signals:

Notice that it involves all other vaccines as well as the target vaccine, but that it looks for disproportionality — where the target adverse event makes up a much greater share of all adverse events when looking at the target vaccine vs. all other vaccines. The cutoff value is PRR = 2, so that twice the share of all reports are for the event.

Evidence suggests that the proportion of all adverse event reports for MMR vaccine which involved ASD grew 6-fold from 1991 to 1998. If there had not been a safety signal back in 1991, then there still would have been one by 1998 — when the proportion grew 6-fold (assuming the proportion for all vaccines had been stable).

Indirect (circumstantial) evidence suggests that the proportional reporting ratio (PRR) for autism and MMR vaccine threw a safety signal by 1998 (because the proportion grew 6-fold), but that officials either ignored the signal or willfully swept it under the rug (i.e., tried to “hide” the signal).

Reference

[retracted Wakefield report] — Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, Malik M, Berelowitz M, Dhillon AP, Thomson MA, Harvey P, Valentine A, Davies SE, Walker-Smith JA. Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children. Lancet. 1998 Feb 28;351(9103):637-41. doi: 10.1016/s0140-6736(97)11096-0. Retraction in: Lancet. 2010 Feb 6;375(9713):445. Erratum in: Lancet. 2004 Mar 6;363(9411):750. PMID: 9500320. https://pubmed.ncbi.nlm.nih.gov/9500320/

[pharmacovigilance: disproportionality analysis] — https://www.ncbi.nlm.nih.gov/books/NBK4056/

[ASD notes for this report] — Spreadsheet data analysis.