Measles Vaccine (What? Again?)

Much has been made in the past couple of weeks of Senator Rand Paul’s (R-KY) comments about the neurological complications of the measles vaccine.  He recanted his ill-advised comments several days later, but they linger on, and many others have commented on his comments.  Ad nauseam.  Some commentators, in an effort to emphasize the safety of the vaccine and encourage people to get vaccinated or get their children vaccinated, have denied that there have ever been any severe side effects (a scientist would call them ‘adverse reactions’) at all.  Strictly speaking, neither is correct.

The measles vaccine has been out since the early 1970’s in the United States, and since that time a number of adverse reactions have occurred in the days, weeks and months after some people were immunized.  I use that convoluted language to emphasize a point.  Adverse reactions can’t occur until the vaccine is given.  You certainly can’t get a bad reaction to a vaccine before it’s given, can you?  Therefore, timing is important.  And just because a person receives a vaccine and gets a bad reaction, that by itself doesn’t prove that the reaction was caused by the vaccine.  That being said, many reactions to measles vaccine have been reported.  Autism is not one of them.  (Measles vaccine is now given either as a trivalent vaccine along with mumps and rubella, or as a tetravalent vaccine: measles, mumps, rubella, and varicella.).  Most reactions have been mild, such as fever or a mild rash.  Some have been more severe, including seizures, joint pain and stiffness, low platelet count.  Some have been very severe, including long-term seizures, even permanent brain damage.  It is this last point to which Senator Paul was probably referring.

The reason these reactions are related to measles vaccine is, again, timing.  They occurred after the vaccine was given.  That doesn’t prove unequivocally that the reactions were due to the vaccine, but with some reactions, such as fever and a mild rash, the sheer number of cases of these reactions pretty well implicates the vaccine.  But the same can’t be said for the serious reactions.  So few cases of seizures and permanent brain damage have been reported we just can’t ascribe them to the vaccine.  There’s not enough data.

The only way to really prove that severe brain damage has been caused by the vaccine would be to take hundreds of thousands of children and divide them into two groups.  That is, it would have to be done as a double-blind trial.  One group would receive the vaccine, the other a placebo.  Then we’d look for adverse reactions.  They should occur only in the vaccinated.  But such a trial would certainly be time consuming, expensive, unnecessary, and most important of all, grossly unethical.  So, all we do is report adverse reactions when they occur.

The reduction in number of cases of measles after the introduction of the measles vaccine certainly justifies the continued use of the vaccine.  Measles is not just a bad cold with a rash.  The disease itself can cause neurological complications, even death.  The only way we’ll ever be free of the scourge of measles will be when it is eradicated from the earth.  I have no idea what Rand Paul will comment on then.

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