Marc Lipsitch, United States of America

Harvard T.H. Chan School of Public Health Department of Epidemiology, Center for Communicable Disease Dynamics

Author Of 1 Presentation

ESTIMATING THE CONTRIBUTION OF DIFFERENT AGE STRATA TO VACCINE SEROTYPE PNEUMOCOCCAL TRANSMISSION IN THE PRE VACCINE ERA, A MODELLING STUDY (ID 411)

Session Name
Population Sciences - Epidemiology, Economics, and Mathematical Modelling

Abstract

Background

Herd protection has contributed greatly to PCV impact and may enable use of reduced dose schedules. We estimated which population age groups contribute most to VT pneumococcal transmission and hence herd effects

Methods

We used transmission models to mirror pre PCV epidemiology in England & Wales, Finland, Kilifi in Kenya and Nha Trang in Vietnam and extracted the per capita and population based contribution of different age groups to VT transmission.

Results

<1y old infants cause frequent secondary vaccine type infections per capita. However, 1-5y olds have the much higher contribution to the force of infection at 51%(28-73), 40%(27-59), 37%(28-48) and 67%(41-86) of the total infection pressure in E&W, Finland, Kilifi and Nha Trang, respectively. Unlike the other settings, school age children in Kilifi were the dominant source for VT infections with 42% (29-54) of all infections caused. Similarly, the main source of VT infections in infants are pre-school children and in Kilifi 39%(28-51) of VT infant infections stem from school age children, whereas this was below 15% in the other settings.

Conclusions

Pre-school children are key PCV targets for achieving herd immunity. In highly endemic settings school children may substantially contribute to transmission and may have little PCV protection with current schedules.

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