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

Abstract

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 greater than or equal to 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.

Pneumococcal Capsules and Their Types: Past, Present, and Future

“…Second, it showed poor effectiveness against nonbacteremic or community-acquired pneumonia (163) and against IPD in chronically ill patients (163) and individuals aged 75 years or older (164). Third, it may not prevent nasopharyngeal (NP) colonization (165)(166)(167) or mucosal infections (nonbacteremic pneumonia and otitis media) (168,169). Finally, antibody concentrations after subsequent doses of PPV23 appear to be lower than those after primary vaccination (170,171); this hyporesponsiveness is related to the large amount of PS in PPV23, which is thought to exhaust the memory B-cell pool without replenishment (172).…”

“…Because pneumococcus spreads from the carriage state, the unvaccinated were protected against vaccine-type IPD due to reduction of its carriage in the community after PCV immunization of infants (194). Such herd effects were not observed with the introduction of PPV23, likely because PPV23 was not given to young children, who are the main carriers of pneumococci, and PS vaccines do not reduce carriage of vaccine serotypes (165)(166)(167).…”

“…This phenomenon is referred to as "serotype replacement" or "serotype shift" and is particular to PCVs given that PPV23 did not alter carriage (165)(166)(167). As a result of serotype replacement, the protective coverage of PCVs has gradually diminished.…”

Indirect Effect of Conjugate Vaccine on Adult Carriage ofStreptococcus pneumoniae:An Explanation of Trends in Invasive Pneumococcal Disease

“…One early study that used a quadravalent vaccine containing ∼30-60 mg of polysaccharide from serotypes 1, 2, 5, and 7 demonstrated reduced colonization with these serotypes [31]. However, more-recent studies that used commercially available 14-and 23-valent pneumococcal polysaccharide vaccines did not demonstrate any influence of immunization on colonization [32][33][34][35].…”

Pneumococcal carriage in children during their first two years: important role of family exposure

“…4 Exposure while the child is in day care has also been considered, and the magnitude of its effect has been assessed in terms of either the time spent in day care 5 or the size of the day care group. 2,6 In addition to the actual number of individuals in contact with the child, the nature of contact is assumed to affect intensity of transmission. In the pioneer studies of the 1950s, crowding, and therefore close contacts, were suggested as an important risk factor for pneumococcal transmission and carriage.…”