Persistence of immunity in children immunised with 13-valent pneumococcal conjugate vaccine and impact on nasopharyngeal carriage: a cross-sectional study

Abstract

In 500 children aged ≤10 years after 13-valent pneumococcal conjugate vaccine (PCV)13 immunisation in different schedules, serotypes 19A-specific and 19F-specific immunoglobulin G (IgG) were predicted to persist above 0.35 µg/mL for ≥10 years in all groups, likely due to PCV13-induced memory with natural boosting from residual diseases and colonisation. Generally, serotype-specific IgG could persist above 0.35 µg/mL longer (≥5 years) in the catch-up group than in the 2+1 and 3+1 immunisation groups. 14.5% of the carriage isolates belonged to PCV13 serotypes; statistical analysis revealed that a high serum IgG level (>10.96 µg/mL) will be required to eliminate the point-prevalence nasopharyngeal carriage of serotype 19A.

Vaccination following the expanded programme on immunization schedule could help to reduce deaths in children under five hospitalized for pneumonia and severe pneumonia in a developing country

“…This might be the impact of an overall improved immunity potentially caused either by the production of antibodies or activation of immunologically competent cells through the stimulation of the body`s immune system among the vaccinated children (21). There was also a persistence of immunity in children who had the PCV vaccination as was observed in a previous study (30). The observation of a lower risk of diarrhea among the immunized children, compared to unimmunized children is also consistent with the previous study (31).…”

Serotype transmission dynamics and reduced incidence of invasive pneumococcal disease caused by different serotypes after implementation of non-pharmaceutical interventions during COVID-19 pandemic

“…Although the reduction could be partly linked to indirect effect on IPD in adults after the childhood PCV13 vaccination and 23-valent polysaccharide vaccine (PPV23) use for adults aged ≥75 years [10], such dramatic reduction within one year apparently was related to the NPIs deployed in the pandemic era. In a recent study we failed to detect serotype 3 by culture and PCR from the nasopharynx of children; however, we observed elimination of serotype 3 IPD cases in children (<5 years) and in contrast, the continued prevalence of serotype 3 IPD in older adults (>65 years), meaning that adults are potential reservoirs for serotype 3 from where adult pneumococcal infections and transmissions to their close contacts can occur [10,12]. NPIs that were initiated by authorities in January 2020 to reduce transmission of SARS-COV-2 at crowded or enclosed places were recommended throughout the study period.…”