To see the impact of PCV-10 on meningitis, pneumonia and sepsis by using “before-after” and case-control study using “indirect cohort”. This study will be done in a rural population-based site (Mirzapur), using the baseline data of 2005 to 2008.
Background and rationale of the study:
Bangladesh has high burden on Invasive Pneumococcal Disease (IPD) which is the major cause of childhood pneumonia, meningitis and sepsis among children under five years of age(1; 2).Effective vaccine against Streptococcus pneumoniae has been available since 2000, and World Health Organization (WHO) recommended inclusion of PCV in childhoodimmunizationprogramin 2006(3).
However,the impact of the vaccine depends on the serotype formulation of the particular PCV and the types circulating in the specific population(4). The net impact of PCV is also dependent on the circulating non-vaccine serotypes as replacement disease caused by emerged non-vaccine type pneumococcus may erode the impact of PCV (4).At the same time, secular changes in pneumococcal serotype can be wrongly considered as replacement disease. Considering these complex dynamics, WHO emphasized on monitoring the impact of PCV after its introduction in the routine immunization program(5; 6).
In South Asia,Pakistan is the first Asian country to introduce PCV-10 and Bangladesh is planning to introduce it in the middle of 2013 with support from GAVI. Unlike other Asian countries, who are lagging behind in generating data on the burden of IPD, several investigators in Bangladesh have collected high quality pre-PCV implementation data on disease burden from population-based field sites and high throughput sentinel sites (1; 2; 7).Therefore, Bangladesh,with the availability of substantial pre-introduction disease burden data and well-establishedfield sites, offers a unique opportunity to conduct an assessment of PCV effectiveness and generate high quality data.
An impact study of PCV in Bangladesh has specific importance as about half of the pneumococcal isolates in Bangladesh are non-vaccine type and secular change in serotype distribution is common(7; 8).Availability of data at real time and theirappropriate interpretation could meaningfully influence the policy makers of the country to continue the investmentfor Pneumococcal vaccine, while GAVI support gets reduced.
In addition, many Asian countries have not yet decided on introduction of PCV. Evidence of impact of PCV on IPD in Bangladesh is likely to influence policy makers in neighboring countries for the introduction of the vaccine in their national immunization programs (NIP).
Primary objectives of the study are to:
1. Quantify the effects of PCV-10 on the incidence of vaccine type (VT) invasive pneumococcal disease (IPD) amongchildren 2. Assess the effectiveness of PCV-10 against VT-IPD among children 3. Assess the impact of PCV-10 on non-vaccine type (NVT)IPDamong children The secondary objectiveof the study is to quantify the effects of PCV-10 introduction on all IPD amongchildren