Dr. Kevin Connolly:

By law, the contents of the PIL and the summary of product characteristics, SmPC, must be provided. On the issue of the number of doses, the vaccines are given for priming and boosting. The first vaccination signals to one’s immune system that it needs antibodies, while the second gives an extra boost. It was found, initially, that if three vaccinations were given - at zero, one or two months and six months - there was stepwise boosting. The companies were also asked to conduct trials involving two vaccinations - at zero and six months - and it was found that the response to the two doses was as good as the response to three. Therefore, fewer doses result in the same immune response.