Academic journal article Bulletin of the World Health Organization

Sentinel versus Population-Based Surveillance of Pneumococcal Conjugate Vaccine effectiveness/Suivi Compare D'un Echantillon Sentinelle et De la Population Quant a L'efficacite Du Vaccin Conjugue Contre le pneumocoque/Efectividad De la Vacuna Antineumococica Conjugada: Comparativa Entre Un Sistema De Vigilancia Centinela Y Un Sistema De Vigilancia Poblacional

Academic journal article Bulletin of the World Health Organization

Sentinel versus Population-Based Surveillance of Pneumococcal Conjugate Vaccine effectiveness/Suivi Compare D'un Echantillon Sentinelle et De la Population Quant a L'efficacite Du Vaccin Conjugue Contre le pneumocoque/Efectividad De la Vacuna Antineumococica Conjugada: Comparativa Entre Un Sistema De Vigilancia Centinela Y Un Sistema De Vigilancia Poblacional

Article excerpt

Introduction

Every year Streptococcus pneumoniae, or pneumococcus, causes an estimated 826 000 deaths worldwide in children under 5 years of age. (1) In 2000, a seven-valent pneumococcal conjugate vaccine (PCV7) was introduced in the United States of America. The result was a dramatic, sustained reduction in invasive pneumococcal disease (IPD) in young children. (2,3) Moreover, a very similar nine-valent pneumococcal conjugate vaccine (PCV9) that contains the seven S. pneurnoniae serotypes in PCV7 (i.e. serotypes 4, 6B, 9V, 14, 18C, 19F and 23F) plus serotypes 1 and 5 has been shown to be efficacious in developing countries (4,5) and the World Health Organization (WHO) has recommended that all countries introduce pneumococcal conjugate vaccines into their routine childhood immunization programmes. (6) As with other new vaccines, measuring the effect of pneumococcal conjugate vaccines helps policy-makers determine whether the benefits of their introduction and sustained use outweigh their costs. (7)

Trends in the occurrence of a vaccine-preventable disease after a vaccine is introduced can be assessed by either population-based or sentinel surveillance. Population-based surveillance involves identifying all new cases of the disease under surveillance in a defined population. The data obtained can be used to calculate the disease incidence rate since the size of the population under surveillance is known. In contrast, sentinel surveillance involves monitoring a disease at a single facility or a small number of facilities. Generally, incidence rates cannot be derived from sentinel surveillance data since the population covered is rarely known and the data obtained may not be representative of the catchment area. However, sentinel surveillance usually requires fewer resources than population-based surveillance. (8) The feasibility of sentinel surveillance has led WHO to recommend that countries adopt the approach for monitoring the effect of newly introduced vaccines, including pneumococcal conjugate vaccines. (9) Sentinel surveillance systems have, nonetheless, several limitations and it is not clear whether even well-functioning systems can provide the data required for evaluating the effect of a new vaccine. However, studies have shown that sentinel systems involving hospitals in the United States can provide a reasonably accurate assessment of trends in antibiotic resistance (10) and that sentinel surveillance in antenatal clinics in developing countries can be used to assess the prevalence of human immunodeficiency virus infection. (11)

In this study, we used data from the Active Bacterial Core surveillance system in the United States to determine whether a sentinel surveillance system involving either individual hospitals or groups of hospitals can provide estimates similar to those based on data from a population-based surveillance system when used to quantify the effect of introducing PCV7 on the occurrence of laboratory-confirmed IPD requiring hospitalization among children aged under 5 years.

Methods

The Active Bacterial Core surveillance system in the United States performs active, population-based surveillance for IPD, which is defined as being present when pneumococcus is isolated from normally sterile body fluid or tissue, such as blood, cerebrospinal fluid or pleural fluid, in an individual who is resident in a surveillance area on the date of culture. (3,12)

We obtained data from this surveillance system on all hospitalized IPD cases identified in children aged under 5 years between 1 January 1998 and 31 December 2006. We adopted 2006 as the endpoint of the study because that year recorded the lowest incidence of IPD to date in the age group. (3) Throughout the study period, the Active Bacterial Core surveillance system monitored IPD in all eight counties in the state of Connecticut and in 49 counties overall in the states of California, Georgia, Maryland, Minnesota, New York, Oregon and Tennessee. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.