Does the Order in Which Vaccines Are Administered Affect Pain Response? A Randomized, Double-blind, Clinical Trial of Pentacel vs. Prevnar

Childhood vaccination is one of the most effective public health measures worldwide, with few serious adverse effects reported. However, pain on vaccination continues to be a frequent occurrence and is the most common cause of childhood iatrogenic pain. In a recent study of paediatricians in the USA, more than ninety percent reported at least one parental vaccine refusal in the past year. The most common concerns cited by parents were short-term reactions and pain from multiple injections.

One of the factors responsible for vaccination pain is the vaccine material itself. Even the same vaccine, when made by different pharmaceutical companies may produce different pain responses. Anecdotal reports from doctors and nurses indicate that Pentacel (DPTaP+Hib) is a relatively painless vaccine to administer whereas Prevnar (conjugated pneumococcal vaccine) causes significant pain on injection and severe distress to the infant being vaccinated. For this reason, many vaccinators administer Pentacel [DPT] prior to Prevnar [PCV] when providing both vaccines in one visit. However, the difference in infant pain responses has not been documented. Although it has been shown that very early pain events affect infants' later experience of pain, it has not been demonstrated that the sequence in which vaccines are administered affects pain response. This study will assess whether there should be a predetermined sequence recommended for administering these two vaccines, with the less painful vaccine (Pentacel) being given first.