A Small Fraction of the Usual (But Scarce) Meningitis Vaccine Adequately Effective

by Tanya Thomas on Dec 9 2008 8:32 AM

A new study has discovered that just one-fifth of the standard dose of the commonly used meningitis vaccine is as effective as the full dose.

Scientists hope that this new finding may 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.

Scientists conducted a randomized clinical trial of 750 healthy volunteers (2-19 years old) in Uganda in 2004.

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).

Keeping in mind 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 were used for 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.