“…Based on these experiences, a population seroprevalence study was conducted in 2009 in Medellín, which estimated the prevalence of antibodies in the population (26)(27)(28)(29)(30) and obtained detailed information on the history of vaccination and the biological and social factors that could influence the presence of antibodies and guide vaccination policies based on the evidence of local epidemiology, as well as the use of mathematical modeling to estimate the critical proportion of immunity and the basic and effective reproductive number indicating the level of achievement of disease elimination (27,31). The percentage of participation in this population-based seroprevalence study was 88,5% (26) during a time of armed conflict in the city, which implied high costs, greater efforts and additional time.…”