An Indonesian child looks on as a paramedic injects measles vaccine in 2006.

Infants who receive routine vaccine injections in a certain order during a trip to the doctor seem to experience less pain, say doctors who suggest giving the least painful one first.

Pain was reduced in infants who received the pneumococcal conjugate vaccine (PCV) following the combination vaccine for diphtheria, polio, tetanus, pertussis and Haemophilus influenzae type b (DPTaP-Hib), Dr. Moshe Ipp of Toronto's Hospital for Sick Children and his colleagues reported in the May issue of the Archives of Pediatrics & Adolescent Medicine.

"We recommend that the order of vaccine injections be the DPTaP-Hib vaccine followed by the PCV," the study's authors concluded in the study.

Giving the combination vaccine first is "simple, and cost free and easy to incorporate" into practice, Ipp said.

To come to that conclusion, the researchers studied 120 healthy infants aged two to six months. In 2006 or 2007, half were randomly assigned to receive PCV first and half had the combination vaccine first.  A nurse preloaded the syringes, and neither the pediatrician nor the parent knew which vaccine was being given.

Infants were videotaped and their pain was assessed on scale based on their facial expression, crying and movements after vaccination. Parents were also asked to assess their children's pain on a scale of zero to 10.

Infants given the less painful vaccine first experienced less pain overall compared with those given the vaccines in the reverse order. Pain also increased from the first to second injection, regardless of the order, the researchers found.

'Don't like needles' refrain

Every day, Ipp said children come into his office and ask, "Am I getting a shot today?" It's a frequent question that flies in the face of what physicians and parents have said for years about how the shots won't hurt and will only take a second.

"The kids are giving us some other feedback, which is say, they don't like needles," Ipp said when asked why he became interested in studying the pain response of infants. "They seem to remember this."

Reducing pain from vaccinations in children is important given that in a recent study of U.S. pediatricians, more than 90 per cent reported at least one parent in their practice had refused to have a child vaccinated in the previous year, most commonly because of pain caused by multiple vaccines.

The World Health Organization estimates 100 million injections are given to children each year to prevent infectious diseases.

Distraction techniques

Giving the more painful injection first may focus an infant's attention on the injection and activate pain processing centres in the brain that boost the intensity of pain signal.

Doctors and nurses could start giving the least painful vaccine first immediately, although the Help in Kids team of doctors, psychologists and public health experts is putting this recommendation and others into more formal guidelines, Ipp said.

The researchers suspect that the more acidic nature of the pneumococcal vaccine may make it more painful, which they suggest the pharmaceutical industry could pay attention to when developing new vaccines.

The team's other recommendations for doctors and nurses include:

  • Giving a vaccine quickly without pulling back on the plunger.
  • Vaccinating infants under the age of one in the leg, and using the arm for older children, who complain and limp less when it's given that way.
  • Putting a topical anesthetic on the site of injection or giving a sugar solution, particularly for newborns.
  • Distracting the infant, and having a parent hold the child.

The study was funded by an unrestricted grant from vaccine maker Sanofi Pasteur. Co-author Prof. Anna Taddio of the University of Toronto and the Help in Kids project are funded by the Canadian Institutes of Health Research. The Pediatric Outcomes Research Team is supported by a grant from The Hospital for Sick Children Foundation.