Decline in pneumococcal disease in unimmunized adults is associated with vaccine-associated protection against colonization in toddlers and preschool-aged children

Abstract

Conflicts of Interest: Within the last two years, DMW has received consulting fees from Affinivax and Pfizer. RD has received grants and consulting and speaker fees from Pfizer; grant and consulting fees from MSD and consulting fees from MeMed. GRY has received consulting fees from Pfizer and research support from Pfizer and MSD. ABSTRACTVaccinating children with pneumococcal conjugate vaccines disrupts transmission, reducing disease rates in unvaccinated adults. When considering changes in vaccine dosing strategies (e.g., removing doses), it is critical to understand which groups of children contribute most to transmission to adults. We used data from children and adults in Israel to evaluate how the buildup of vaccine-associated immunity in children was associated with declines in IPD due to vaccine-targeted serotypes in unimmunized adults. Data on vaccine uptake and prevalence of colonization with PCV-targeted serotypes were obtained from a unique study conducted among children visiting an emergency department in southern Israel and from surveys of colonization from central Israel. Data on invasive pneumococcal disease in adults were obtained from a nationwide surveillance study. We compared the trajectory of decline of IPD due to PCVtargeted serotypes in adults with the trajectory of decline of colonization prevalence and trajectory of increase in vaccine-derived protection against pneumococcal carriage among different age groupings of children. The declines in IPD in adults were most closely associated with the declines in colonization and increased vaccination coverage in children in the range of 36-59 months of age. This suggests that preschool-aged children, rather than infants and young toddlers, are responsible for maintaining the indirect benefits of PCVs.

Pneumococcal serotypes causing non-invasive pneumonia in adults from a South Indian tertiary care hospital and the impact of the newer conjugate vaccines

“…The recommended single dose of PCV13 in adults aged ≥65 years, results in a temporary reduction of vaccine serotype carriage for only 6 months after vaccination. Hence, achieving herd immunity to decrease the IPD in adults and the elderly, is associated with the decline in colonization and increased vaccination coverage among toddlers and pre-school-aged children (36–59 months) [ 23 ]. Therefore, catch-up vaccination with PCV in pre-school-aged children and adolescents is important in maintaining the herd effect.…”