One-fifth of the standard dose of a commonly used meningitis vaccine may be as effective as using the full dose. This new finding should allow scarce vaccine resources to be stretched further, especially during epidemics in Africa.
In a study initiated by the Norwegian Institute of Public Health, together with Epicentre (the research arm of Doctors Without Borders/Médecins Sans Frontières), and Mbarara University of Science and Technology in Uganda, immune responses in patients receiving smaller doses of a meningitis vaccine were found to be comparable to a full dose.
In 2004, a randomized clinical trial of 750 healthy volunteers (2 to 19 years old) took place in Uganda. Their immune response, assessed by serum bactericidal activity (SBA), was measured for 1/5 and 1/10 doses compared to a full dose. SBA response and safety/tolerability using 1/5 dose were comparable to a full dose for three serogroups (A, Y, W135), but not a fourth (C).
In view of the current shortage of meningococcal vaccines for Africa, the use of 1/5 fractional doses should be considered as an alternative in mass vaccination campaigns. The study’s findings contributed to a 2007 WHO recommendation that a fractional dosing strategy be utilized in the event of severe vaccine shortages during a meningitis epidemic.
The results have now been published in PLoS Neglected Tropical Diseases.