Eduardo Santacruz-Sanmartín1, Doracelly Hincapié-Palacio2, Marta C Ospina3, Olga Perez-Toro4, Luz M Bernal-Restrepo5, Seti Buitrago-Giraldo6, Viviana Lenis-Ballesteros7, Francisco J Díaz8. 1. Secretary of Health, Medellín, Colombia. Electronic address: santacruzsanmartin@yahoo.com. 2. Epidemiology Group, National School of Public Health, 'Héctor Abad Gómez', University of Antioquia, Medellín, Colombia. Electronic address: doracely@gmail.com. 3. Laboratory of Public Health of the Regional Secretary of Health and Social Protection of Antioquia, Medellín, Colombia. Electronic address: martha.ospina@antioquia.gov.co. 4. Laboratory of Public Health of the Regional Secretary of Health and Social Protection of Antioquia, Medellín, Colombia. Electronic address: olgaperez11@hotmail.com. 5. Laboratory of Public Health of the Regional Secretary of Health and Social Protection of Antioquia, Medellín, Colombia. Electronic address: luzmarinabernal312@hotmail.com. 6. Laboratory of Public Health of the Regional Secretary of Health and Social Protection of Antioquia, Medellín, Colombia. Electronic address: seti.buitrago@antioquia.gov.co. 7. National School of Public Health, 'Héctor Abad Gómez', University of Antioquia, Medellín, Colombia. Electronic address: vileba15@gmail.com. 8. Inmunovirology Group, School of Medicine, University of Antioquia, Medellín, Colombia. Electronic address: francisco.diaz@udea.edu.co.
Abstract
OBJECTIVE: We related seroprevalence and outbreaks data in order to identify factors that could explain the occurrence of outbreaks despite high vaccination coverage in Medellín Colombia. METHODS: Samples from a population seroprevalence data obtained in 2009 in a random survey were analyzed. IgG levels were determined for mumps using 2 commercial tests of 2119 individuals aged 6-64 years. A comparative analysis was undertaken using age-specific mumps seroprevalence data and information of 98 epidemiological investigations of mumps outbreaks reported in 2009. RESULTS: Overall, seroprevalence was 91.6% (95% CI=89.3-93.5%). The age-specific seronegativity was 20.3% and 20.6% in age groups 11-15 years and 16-20 years respectively. Individuals aged 6-20 years were the most affected during outbreaks. In individuals born in 2003, a year after the change in the booster schedule from 10 to 5 years, the proportion of unvaccinated individuals (14%) and those who received only one dose of MMR (45%) increased substantially. On average, 23.5 days elapsed between the onset of symptoms in secondary cases and the outbreak investigation. CONCLUSION: Potential contributing factors for the occurrence of outbreaks of mumps were the relatively high prevalence of seronegativity among individuals aged 11-20 years, delays in investigation and control of outbreaks, and incomplete vaccination schedules.
OBJECTIVE: We related seroprevalence and outbreaks data in order to identify factors that could explain the occurrence of outbreaks despite high vaccination coverage in Medellín Colombia. METHODS: Samples from a population seroprevalence data obtained in 2009 in a random survey were analyzed. IgG levels were determined for mumps using 2 commercial tests of 2119 individuals aged 6-64 years. A comparative analysis was undertaken using age-specific mumps seroprevalence data and information of 98 epidemiological investigations of mumps outbreaks reported in 2009. RESULTS: Overall, seroprevalence was 91.6% (95% CI=89.3-93.5%). The age-specific seronegativity was 20.3% and 20.6% in age groups 11-15 years and 16-20 years respectively. Individuals aged 6-20 years were the most affected during outbreaks. In individuals born in 2003, a year after the change in the booster schedule from 10 to 5 years, the proportion of unvaccinated individuals (14%) and those who received only one dose of MMR (45%) increased substantially. On average, 23.5 days elapsed between the onset of symptoms in secondary cases and the outbreak investigation. CONCLUSION: Potential contributing factors for the occurrence of outbreaks of mumps were the relatively high prevalence of seronegativity among individuals aged 11-20 years, delays in investigation and control of outbreaks, and incomplete vaccination schedules.