Monthly Autism Safety Signal (Feb 1995)

Post #856

May 26, 2024

This post extends prior work here.

A monthly safety signal for an adverse event means that twice or more of the proportion of all adverse events for a given product are made up by a target adverse event — when compared to the proportion that that event makes up of adverse event reports for all other vaccines. You get a Proportional Reporting Ratio (PRR).

Here is the PRR for MMR vaccine and autism for those receiving their dose during the month of February 1995:

At top left is the overall PRR using onset dates reaching beyond 120 days, but for the purpose of pharmaco-vigilance, CDC would be looking at event reports happening within about 4 months (120 days) of time of vaccination — so the analysis was repeated at right, using only those reports with onset within 120 days of dosing.

The PRR was 5.62 for the month of February 1995 — indicating an official safety signal. An important aspect of this official safety signal from 29 years ago is that it precedes a pivotal 1998 report by Wakefield et al. suggesting a link between MMR vaccines and autism.

The CDC has not admitted that there is a link, even though it has been sitting on the data above for 29 years. In their defense, the CDC might try to say that they are aware of the monthly safety signal, but that they performed “due diligence” with regard to follow-up research — only to then discover that this 1995 signal was a false alarm.

But in a follow-up analysis, the link is revealed to be authentic (not due to chance).

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