Serogroup B meningococcal disease during Hajj: preparing for the worst scenario.

The Islamic Hajj pilgrimage to Mecca, Saudi Arabia has historically been associated with outbreaks of serogroup A and W135 meningococcal disease. Prevention against meningococcal disease has principally been vaccination with meningococcal polysaccharide vaccines, either in a bivalent serogroup A/C or quadrivalent A/C/Y/W135 form. These interventions have suppressed meningococcal disease since 2002. Countries with large Muslim populations have now started to show a trend of increased serogroup B meningococcal disease, a serogroup for which there is no universal vaccine available. These trends should increase our preparedness to expect a sudden change in the etiology of meningococcal disease during the Hajj.