Vaccine injections are a significant source of pain for infants. Altering the injection speed when administering vaccines may be an effective intervention and is feasible (cost neutral). At present, there are no data regarding impact of injection speed on vaccine injection pain in infants. The aim of this study is to address this knowledge gap and to compare the impact of slow and fast vaccine injection speeds on pain during routine infant vaccinations.

To date, there has been no evidence-based guidance regarding the rate at which vaccines should be injected to minimize pain. This has led to a disparity in practice. Some vaccinators favour a slow rate of injection (around 8-10 sec/mL) while others prefer a more rapid rate of injection (around 2-4 sec/mL).The slow injection method leads to a longer needle dwelling time with the increased possibility of the needle moving around and causing pain by damaging muscle tissue. Rapid injection, on the other hand, may lead to a sudden distension of muscle tissue, which itself could be painful. Allowing the muscle sufficient time to distend in order to accommodate the vaccine might minimize pain. This study will address the identified knowledge gap by comparing pain in infants undergoing routine vaccinations with a fast vs. slow injection speed.

Inclusion Criteria:

• Healthy 2 and 4 month old infants receiving their primary vaccine injections, PediacelTM (0.5mL) and PrevnarTM (0.5mL) (in conjunction with and preceded by oral RotarixTM vaccine) and healthy 6 month old infants receiving their routine vaccine injection, PediacelTM (0.5mL)

Exclusion Criteria:

• Infants with impaired neurological development; history of seizures; administration of sedatives or narcotics in the preceding 24 hours; parental inability to use study tools; parent vaccine refusal; prior participation in the trial; and refusal to be video recorded