Sequence matters when you administer multiple vaccinations to infants, Canadian pediatricians have found. Babies who receive the combination vaccine for diphtheria, polio, tetanus, pertussis, and Hemophilus influenzae type b (DPTaP-Hib) before being given the pneumococcal conjugate vaccine (PCV) appear to experience less pain from the shots.

In a double-blind trial conducted in an outpatient clinic, 120 healthy infants aged 2-6 months were undergoing routine immunization. Half were given the PCV shot first; the remainder received DPTaP-Hib first (Arch Pediatr Adolesc Med. 2009;163:469-472).

Inoculations were videotaped, and pain was assessed using the Modified Behavioral Pain Scale (MBPS). Parents rated their child’s pain on a 10-point visual analog scale (VAS). The presence or absence of crying was also noted.

Mean pain scores were significantly lower on both scales when PCV followed DPTaP-Hib (MBPS score, 7.6 vs. 8.2 for PCV given first; parent VAS score, 4.2 vs. 5.6). Consequently, the study authors recommend starting the double shots with DPTaP-Hib.

The report mentions U.S. research showing that pain has an impact on parental decisions regarding infant vaccination (Am J Prev Med. 2004;26:11-14). More than 90% of pediatricians surveyed reported at least one parent in their practice refused to have a child vaccinated—“most commonly as a result of pain from multiple vaccines.”

“Varying the order of vaccine administration to reduce pain is a strategy [to address this concern] that is simple, effective, cost-free, and easily incorporated into clinical practice,” the authors note.