Laboratory-based surveillance in Latin America: attributes and limitations in evaluation of pneumococcal vaccine impact.

PLAIN LANGUAGE SUMMARYWhat is the context?Infectious disease surveillance is an important epidemiological tool to monitor the health of a population.Surveillence can be used to detect trends in disease activity and to trigger disease control measures.In Latin America, the SIREVA surveillance system monitors occurrence of bacterial pneumonia, sepsis/bacteremia and meningitis.However, passive surveillence systems may understimate disease occurrence.What is new?We compared the number of isolates of invasive pneumococcal disease (IPD), specifically meningitis and sepsis/bacteremia, in children aged <5 years reported in SIREVA data in six countries in Latin America with the expected number of cases based on regional estimates of IPD incidence.Our results show that the number of isolates reported by SIREVA was consistently lower than the estimated number of cases, across all six countries and all the years available.The percent difference between SIREVA-reported isolates and estimated number of cases was variable between countries, ranging from 43-83% in chile to 1.4-3.5% in Mexico.What is the impact?Passive surveillance systems such as SIREVA are important tools for monitoring disease incidence, but they are likely to underestimate pneumococcal disease occrruence.This under-reporting will limit the precision of surveillance data in monitoring changes in disease incidence after vaccine introduction, and this needs to be considered when assessing vaccine impact.