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Immunization in Infants: Long Needle or Short Needle?

Vaccination with long needles resulted in fewer local reactions.

Little is known about the effect of needle size on vaccine efficacy and side effects. In a randomized clinical trial from the U.K., 696 healthy infants were vaccinated at 2, 3, and 4 months of age using the standard 25-gauge 25-mm-long needle, a slightly thicker one (23 gauge, 25 mm long), or a slightly shorter one (25 gauge, 16 mm long). The infants received a combined diphtheria, tetanus, whole cell pertussis, and Haemophilus influenzae type b vaccine in one leg and a serogroup C meningococcal glycoconjugate vaccine in the other.

Parents maintained diaries on reactions following immunizations. Infants vaccinated with standard-length needles of both gauges experienced significantly fewer local reactions (i.e., swelling, redness, hardness, or tenderness) than infants vaccinated with shorter needles; this difference was not significant at 6 hours postimmunization, but was significant at days 1, 2, and 3. Of 11 infants who were withdrawn from the study because of extensive redness and swelling, 10 had been vaccinated using shorter needles. Immunogenicity, as measured by antibody concentrations to the various antigens at 28 to 42 days after the third dose, was similar in the three groups.

Comment: These results support the American Academy of Pediatrics' recommendation that infants from 2 to 12 months of age be vaccinated with 7/8-inch (22.2 mm) to 1-inch (25.4 mm) needles. Longer needles appear to elicit fewer local reactions — possibly because, as an editorialist comments, they ensure that vaccines are injected into muscle rather than into subcutaneous tissue. At the time of publication, the full text of the original article was available free of charge.

— Howard Bauchner, MD

Published in Journal Watch Pediatrics and Adolescent Medicine November 8, 2006

Citation(s):

Diggle L et al. Effect of needle size on immunogenicity and reactogenicity of vaccines in infants: Randomised controlled trial. BMJ 2006 Sep 16; 333:571-4.

• Original article (Subscription may be required)
• Medline abstract (Free)

Zimmerman RK. Size of the needle for infant vaccination. BMJ 2006 Sep 16; 333:563-4.

• Original article (Subscription may be required)
• Medline abstract (Free)