A Longitudinal Study of the Nasopharyngeal Carriage of Pneumococci as Related to Pneumococcal Vaccination in Children Attending Day-care Centres

A long-term study of nasopharyngeal carriership in 405 children, aged 6 months to 5 years, attending day-care centres was performed. The effect of pneumococcal vaccination was evaluated in a double-blind investigation where the children received either Pneumovax (a 14-valent pneumococcal vaccine) or saline. Nasopharyngeal cultures were taken monthly by a trained nurse during a 2-year follow-up period. No difference in pneumococcal carriage was found between vaccinees and controls. Pneumococci were found in 31.9% of all cultures. In day-care centres attended by $45 children the carriage rate of pneumococci was significantly higher than in centres with less than 45 children. Spreading of pneumococci within day-care centres was common but rather short-lived. Children younger than 2 years showed the highest carriage rates. Pneumococci of group 6 were carried most frequently and for longer periods than groups 19 and 23.