Fractional doses of inactivated poliovirus vaccine in Oman

N Engl J Med. 2010 Jun 24;362(25):2351-9. doi: 10.1056/NEJMoa0909383.


Background: We conducted a clinical trial of fractional doses of inactivated poliovirus vaccine administered to infants in Oman, in order to evaluate strategies for making the vaccine affordable for use in developing countries.

Methods: We compared fractional doses of inactivated poliovirus vaccine (0.1 ml, representing one fifth of a full dose) given intradermally with the use of a needle-free jet injector device, with full doses of vaccine given intramuscularly, with respect to immunogenicity and reactogenicity. Infants were randomly assigned at birth to receive either a fractional dose or a full dose of inactivated poliovirus vaccine at 2, 4, and 6 months. We also administered a challenge dose of monovalent type 1 oral poliovirus vaccine at 7 months and collected stool samples before and 7 days after administration of the challenge dose.

Results: A total of 400 infants were randomized, of whom 373 (93.2%) fulfilled the study requirements. No significant baseline differences between the groups were detected. Thirty days after completion of the three-dose schedule, the rates of seroconversion to types 1, 2, and 3 poliovirus were 97.3%, 95.7%, and 97.9%, respectively, in the fractional-dose group, as compared with 100% seroconversion to all serotypes in the full-dose group (P=0.01 for the comparison with respect to type 2 poliovirus; results with respect to types 1 and 3 poliovirus were not significant). The median titers were significantly lower in the fractional-dose group than in the full-dose group (P<0.001 for all three poliovirus serotypes). At 7 months, 74.8% of the infants in the fractional-dose group and 63.1% of those in full-dose group excreted type 1 poliovirus (P=0.03). Between birth and 7 months, 42 hospitalizations were reported, all related to infectious causes, anemia, or falls, with no significant difference between vaccination groups.

Conclusions: These data show that fractional doses of inactivated poliovirus vaccine administered intradermally at 2, 4, and 6 months, as compared with full doses of inactivated poliovirus vaccine given intramuscularly on the same schedule, induce similar levels of seroconversion but significantly lower titers. (Current Controlled Trials number, ISRCTN17418767.)

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Viral / biosynthesis
  • Developing Countries
  • Female
  • Humans
  • Immunity, Humoral
  • Immunity, Mucosal
  • Infant
  • Injections, Intradermal
  • Injections, Intramuscular
  • Injections, Jet
  • Male
  • Oman
  • Poliomyelitis / prevention & control*
  • Poliovirus / immunology
  • Poliovirus Vaccine, Inactivated / administration & dosage*
  • Poliovirus Vaccine, Inactivated / adverse effects
  • Poliovirus Vaccine, Inactivated / immunology*
  • Vaccination / adverse effects


  • Antibodies, Viral
  • Poliovirus Vaccine, Inactivated

Associated data

  • ISRCTN/ISRCTN17418767