There is no causal link between MMR vaccine and autism

EDITOR—Nichol et al considerably understate their case when they write “chance alone dictates that some cases [of autism] will appear shortly after vaccination.”1 Such a temporal association is unremarkable, given the epidemiology of autism and MMR vaccine.

Over the time described by Wakefield et al2 MMR vaccine was given to around 600 000 children each year in Britain3 and the prevalence of autistic spectrum disorders was 91/100 000.4

Assuming that the diagnosis of autism is evenly distributed over the second and third years of life and that the incidence over this period approximates to the current prevalence,5 over the eight years that the reported cases represent autism would have been diagnosed in around 364 cases in the two months after MMR vaccination (the time that the authors regard as noteworthy (((91/100 000) ×600 000)×8)×(2/24)=364). The reported cases therefore represent a fraction of the cases of autism whose onset coincides with the administration of MMR vaccine.

Those giving MMR vaccine had no input into editorial

EDITOR— The editorial by Nicoll et al about a possible link between measles, mumps, and rubella (MMR) vaccine and autism1 is not helpful for those working in primary care who actually give the vaccine, are concerned about its potential and actual side effects, and have to deal with the effects of a scare story, as in this case. General practitioners, health visitors, and practice nurses, who all give this vaccine regularly, have had no formal input into the editorial and have not participated in the expert committee set up to review the MMR reports.

It is all very well to ask an expert committee for an opinion based on research in secondary, and even tertiary, care. A more valuable opinion of what really happens in practice, however, would be available from those who actually have the day to day experience of this vaccine in use, and that includes parents.

Public concern about the safety of MMR vaccine has not only been raised by the study of Wakefield et al.2 In 1992 and 1993 one of the commonly used MMR vaccines was withdrawn because of recurrent reports of adverse effects. I remember seeing three cases of encephalitis after MMR vaccinations in my own baby clinic at that time, although thankfully these resolved.

Concerns after a television advertisement for the MR booster campaign in 1994 and 1995 left parents wondering whether the advertisement was meant to scare them into having the vaccination done. This may explain in part the media response to Wakefield's study.2

What we would have needed from the editorial were some straightforward figures to help parents understand why their child should have this vaccine. An unvaccinated child is 20 times more likely to have a serious complication from measles, mumps, or rubella than he or she would be after MMR vaccination.

Finally, I assume that the last paragraph of the editorial contains an error: “While vaccine can be guaranteed to be without any risk ….”1 No vaccine or drug can ever be guaranteed to be without any risk.

Medical practitioners need to give more than reassurance

EDITOR—Can I present a challenge to Nicoll et al?1 As a parent of young children I have become aware of a website— “The informed parent” (http://www.unc.edu/~aphillip/WNW/vaccine/dvm.txt) that is having a profound influence on many of my non-medical friends who have small children. Although the website is written by a non-physician, it is written in the style of a medical journal, which lends it more authority than it may merit. This website argues that vaccination is dangerous and unnecessary.

The issue is about risk and the perception of risk. There may also be a perception of secrecy about problems with vaccines in the United Kingdom, which is why this website is now so influential. In a consumer led NHS it is no longer sufficient for general practitioners and practice nurses to give simple reassurance.

The challenge is to produce information for parents that is accessible (including on the internet) and balanced, and that addresses the specific concerns that websites such as “The informed parent” engender. This is a particular example of patient empowerment, and the medical profession needs to do more than just convince itself of the safety of vaccination.