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MMR and Measles

Posted by Ed on August 15, 2003

Both the BMJ and the New Scientist are reporting on the rise in the number of measles cases in Britain, and the concurrent fall in the uptake of the MMR vaccine. It seems the disease is in danger of becoming endemic, as the ‘reproductive number’ approaches 1.

From the collected data, the team calculated the “reproductive number” (R), a measure of the likelihood that an infected person infects someone else. When R exceeds 1.0, an epidemic is possible because each infected individual spreads the disease to more than one other person.

The study does not prove causality between the drop in vaccination rate and the increase in outbreaks of the disease, but the increase in the reproductive number correlates with the decrease in vaccination.

Dr Jansen said that although the drop in vaccinations coincides with an increase in the size of measles outbreaks, the conclusion that there is a causal connection cannot be drawn from their data. However, the study does conclude that the “reproductive number” – the mean number of secondary infections per infection, which can be used to predict the course of an epidemic – has increased in recent measles outbreaks in England and Wales. The study’s authors say that the reproductive number is “approximately proportional to the fraction of the population that is not immunised.”

The decrease in uptake of the vaccine followed publicity in the press about the safety of the vaccine. A paper in the Lancet in 1998 by Andrew Wakefield suggested a link between MMR vaccine and autism, but this has been refuted by a number of much larger studies. Read my earlier posting on this subject here.


One Response to “MMR and Measles”

  1. Cenderella said

    I think that the measles is a very serious illness i hope that everyone understands what the measles are

    Be SAFE and stay out of TROUBLE


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