An outbreak of Streptococcus pneumoniae serotype 1 in a closed community in southern Israel.

An outbreak of Streptococcus pneumoniae serotype 1 occurred in a closed community that was characterized by poverty and crowding. Vaccine was administered to individuals aged >2 years; no new cases occurred among vaccine recipients. Six weeks after vaccination, carriage of serotype 1, but not of other serotypes, decreased 8.8-fold. This suggests that the reduction in serotype 1 carriage reflects the natural course of the outbreak rather than a vaccine effect. Polysaccharide vaccine may be helpful in terminating pneumococcal outbreaks but may not affect pneumococcal carriage.