Common side-effects after Pediacel
(the 5-in-1 vaccine)

The graph shows all reactions occurring within a week of the vaccine, so it is most unlikely that all the problems were caused by the vaccines in all the children. However, these are the only details of reactions that the study - sponsored by the manufacturer of the vaccine - provides. It is clear that side-effects were frequent. However, less common, but possibly serious, reactions could easily have been missed because of the small numbers of children involved.

It is possible that the side-effect of a multiple ‘5-in-1’ vaccine like Pediacel may be more than the sum of its individual components, were they all to be given separately; there is evidence that a greater number of vaccine components increases side-effects such as fever and fretfulness. The lack of attention being paid to this problem was acknowledged at the First International Symposium on Vaccine Safety in 2002, “The safety of combined vaccines, for example, requires to be evaluated as most of the available information is derived from studies evaluating the various components separately.” Every vaccine combination should be tested for safety in its own right – something that is not happening.

At the time of the introduction of Pediacel into the routine childhood immunisation schedule in the UK in October 2004, there had been only
one published study on its safety. This involved 560 children, given a nearly identical vaccine, who were only followed up for 3 days after vaccination, unless they had a ‘severe’ reaction in which case they would be followed up for longer. Not all the children were given the Pediacel-like vaccine. Of those who were, two ‘serious’ reactions were reported: one had two periods of strange head movements and the other had several brief episodes of apnoea (stopping breathing). The doctors in the study felt that the vaccine was unlikely to be the cause of either problem, though did not explain how they came to this conclusion.

Other research suggests that the doctors should have less readily exonerated the vaccine; premature babies often suffer episodes of apnoea, slow heart rate (bradycardia) and low blood oxygen after receiving combination vaccines similar to Pediacel.

A further UK trial involved Pediacel itself, which was given along with the Men C vaccine at 2, 3 and 4 months like in the routine UK schedule. Published over a year after the vaccine’s launch, this study confirmed that the vaccine caused fewer reactions than the vaccine it was replacing, which contained the whole-cell whooping cough vaccine. But a high proportion of babies still showed reactions such as irritability and crying. The most frequent are shown in the following graph: