There is no subject that provokes conspiracy theories quite like the immunization of children. That innocent, healthy creatures should have alien substances forcibly introduced into their bodies seems unnatural and almost cruel. As one internet blogger put it:
Don’t take your baby to get a shot, how do you know if they tell the truth when giving the baby the shot, I wouldn’t know because all vaccines are clear and who knows what crap is in that needle.
The most common conspiracy theory at the moment is that children are being poisoned with vaccines to boost the profits of the pharmaceutical companies that make the vaccines. No doubt such companies sometimes get up to no good, as do all organizations staffed by human beings, but that is not also to assert that they never get up to any good.
A relatively new vaccine is that against rotavirus, the virus that is the largest single cause of diarrhea in children. In poor countries this is a cause of death; in richer countries it is a leading cause of visits to the hospital but the cause of relatively few deaths.
Since rotavirus immunization of infants was introduced in the United States, hospital visits and admissions have declined by four fifths among the immunized. However, evidence of benefit is not the same as evidence of harmlessness, and one has the distinct impression that opponents of immunization on general, quasi-philosophical grounds, almost hope that proof of harmfulness will emerge.
A study published in a recent edition of the New England Journal of Medicine examined the question of one possible harmful side-effect of immunization against rotavirus, namely intestinal intussusception, a condition in which a part of the intestine telescopes into an adjacent part, and which can lead to fatal bowel necrosis if untreated.
The authors compared the rate of intussusception among infants immunized with two types of vaccine between 2008 and 2013 with that among infants from 2001 to 2005, before the vaccine was used. There is always the possibility that rates of intussusception might have changed spontaneously, with or without the vaccine, but the authors think that this is slight: certainly there is no reason to think it.
They found that there were 6 cases of intussusception after 207,955 doses of one kind of vaccine, whereas only 0.72 cases would have been expected from the 2001 – 2005 figures. Therefore the risk of intussusception increased 8.4 times after immunization.
The authors found no such increase after the use of another type of vaccine, with 8 cases after 1,301,801 doses administered instead of the expected 7.11. This difference was too small to be statistically significant; it might easily have arisen by chance. However, another study of this vaccine, from Australia rather than the United States, suggested that the size of the risk with this vaccine was similar to that of the other.
Therefore, on the balance of probability, immunization against rotavirus does cause intussusception in infants and is therefore not entirely harmless. To that extent the conspiracy theorists are correct. But good in medicine seldom comes without the possibility of harm (the reverse, alas, is not true), and if doctors never prescribed anything that might do harm as well as good they would not prescribe anything at all. The good must always be weighed against the harm and in this case the balance seems overwhelmingly on the side of the good. The very fact that such huge numbers of cases have to be treated to reveal any harm at all is an indication that, in numerical terms at least, it cannot be very great.