Disease burden and medical cost-analysis of Acute Respiratory Infections in a low-income district of Bogotá
Análisis del costo médico y la carga de enfermedad de las Infecciones Respiratorias Agudas en una localidad de ingresos bajos de Bogotá
Carlos A. Lara-Oliveros1, Diana De Graeve1, Fabián Franco2 y Sandra P. Daza3
1 Universidad de Amberes. Amberes. Belgica. email@example.com; firstname.lastname@example.org
2 Hospital la Victoria. Bogotá. Colombia. email@example.com
3 Hospital San Cristóbal. Bogotá. Colombia. firstname.lastname@example.org
Received 8th September 2014 /Send for Modification 16th November 2015/Accepted 7th March 2016
Objective To estimate the burden of disease and related direct medical cost of Acute Respiratory Infections (ARI) for the health-care system in a low-income district of Bogotá, generated by children under age five and senior population over age sixty.
Methods A cross-sectional, retrospective, patient level study was conducted in San Cristobal district from 2008 to 2012 among the subsidized population. All inpatients and outpatients with ARI from three hospitals were reported. The total and average direct medical costs were estimated and are reported in International Dollars (Int$).
Results It is estimated that, for children, ambulatory incidence rate for ARI varied between 54.4 % and 66.3 % and hospitalization rate between 9.2 % and 12.3 %. The mortality rate in the district oscillated between 18.1 and 27.7 deaths per 100 000. The main medical costs were attributed to hospitalizations, and the total medical hospitalization cost per year estimated ranged between Int$ 1 334 352 and Int$ 2 139 597. In the case of senior population, the ambulatory incidence rate fluctuated between 7.6 % and 10.0 %, and the hospitalization rates between 0.6 % and 2.1 %; the mortality rate ranged between 8.9 and 47.8 deaths per 100 000. Hospitalization cost per year was estimated to be between Int$ 88 957 and Int$ 373 382.
Conclusion Direct medical costs due to ARI have an important disease and direct medical cost burden in this low-income district.
Key Words: Colombia, respiratory tract infections, cost of illness, poverty areas (source: MeSH, NLM).
Objetivo Estimar la carga de enfermedad y los costos médicos directos relacionados con las Infecciones Respiratorias Agudas (IRA) para el sistema de salud en una localidad de bajos ingresos de Bogotá, en niños menores de cinco años y adultos mayores de sesenta años.
Métodos Se realizó un estudio retrospectivo transversal a nivel de paciente en la localidad de San Cristóbal desde 2008 y 2012 en la población subsidiada. Se reportaron todos los pacientes hospitalizados y ambulatorios de tres hospitales públicos debido a IRA. Se estimaron los costos médicos directos relacionados. Los costos fueron convertidos en dólares internacionales (Int$).
Resultados En niños. Se estimó que la incidencia ambulatoria para IRA varió entre 54,4 % y 66,3 % y la tasa de hospitalización varió entre 9,2 % y 12,3 %. La tasa de mortalidad en el distrito osciló entre 18,1 y 27,7 muertes por 100 000 niños. Se estimó que el costo de las hospitalizaciones oscilaron anualmente entre Int$ 1 334 352 y Int$ 2 139 597 representado la más importante carga financiera. En adultos, la incidencia ambulatoria fluctuó entre 7,6 % y 10 %. Las tasas de hospitalización variaron entre el 0,6 % y el 2,1 %. Mientras que la tasa de mortalidad varió entre 8,9 y 47,8 muertes por 100 000. Para hospitalizaciones se estimó un costo total por año entre Int$ 88 957 y Int$ 373 382.
Conclusión Los costos médicos debido a IRA tienen una carga económica importante para el sistema de salud y los hogares en esta localidad.
Palabras Clave: Colombia, infecciones del sistema respiratorio, costo de enfermedad, áreas de pobreza, Colombia (fuente: DeCS, BIREME).
Worldwide, disease burden caused by Acute Respiratory Infections (ARI) in 2011 was estimated at 117 million Disability Adjusted Life Years and 2.8 million deaths (1,2). ARI are among the leading causes of death in children but diagnosis and attribution are difficult (3). ARIs represent an important economic burden (4).
In Colombia, from 2007 to 2011, the number of reported ARI increased, as well as the number of fatalities. In 2011, a cumulative total of 4,168,783 ARIs cases were reported by the national surveillance system (Sistema Nacional de Vigilancia en Salud Pública) and approximately 706 fatalities were reported in children under five years of age (5). The etiology of ARI is given by a diverse group of bacteria and viruses (6).
In 2010, the incidence of respiratory viruses, according to the Colombian National Institute of Health (Instituto Nacional de Salud, INS) showed that the respiratory syncytial virus caused 62 % of the cases studied, followed by influenza viruses (24 %) and parainfluenza viruses (8 %). Children are the most affected group (7). Another age group highly vulnerable to ARI is senior population, causing hospitalizations and mortalities (8).
ARIs are one of the main causes of hospitalization, generating an important health utilization and absenteeism, therefore, impacting the economic system (3,6,9-12). In 2012, nationally, the associated mortality for ARIs was estimated at 13.35 deaths per 100,000 children under five (13).
There is limited data about the direct medical and epidemiological burden of these infections, especially among the low-income population (12,14,15). Understanding the direct medical cost of ARIs is important in order to prioritize a more efficient health intervention to decrease the economic and disease burden. Therefore, the aim of this study is to estimate the direct medical cost of ambulatory and hospitalized cases of ARIs in a low-income district of Bogotá, based on a population of children under five years of age and seniors over sixty years of age.
The population of Bogotá accounts for more than 15 % of the country’s population. Located in Bogotá, the district of San Cristobal had an estimated population of 409,799 in 2011 (16). In 2012, the Gross National Income per capita was estimated at Int$ 4,758.01 for San Cristobal district only (16-19). Approximately 34.0 % of the population of San Cristobal is classified in the two lowest income strata of the country (16,17).
Similarly to the rest of the country, the health system of the population of San Cristobal is covered by two regimes: contributive and subsidized. The contributive system, representing 62.1 % of the district population, includes patients that can afford a premium rate. The subsidized regime, representing 37.9 % of the district population, consists of patients that are not able to pay a premium rate and are allowed to seek health services from public healthcare providers (12,17,20).
A cross-sectional retrospective study was conducted to assess the burden of disease and direct medical cost attributable to ARI between January 2008 and December 2012, in children under five and seniors over sixty years, of the subsidized population, in three hospitals. These two age groups are at considerably higher risk of contracting ARIs and developing severe forms of the diseases (5,21,22).
The Individual Registry of Health Services (Registro Individual de Prestación de Servicios or RIPS) was used, which include the following patient information: identification number, patient name, age, gender, home address, insurance status (subsidized or contributive), purpose of the consultation, treatment, start and end dates of treatment and medical diagnosis codified according to the International Statistical Classification of Diseases and Related Health Problems version 10 (ICD-10) (12,23).
ARIs, according to the INS definition, are defined as "a group of infectious diseases caused by microorganisms that affect the upper and lower respiratory tract over a period of fifteen days, and can vary from a common cold to more severe complications such as pneumonia". For this study, the guidelines of the INS to classify ARIs were used, taking into account the following ICD-10 codes (6, 24):
- Acute infections of the upper respiratory tract: J00 to J06.
- Influenza (excluding influenza with pneumonia): J09, J10.1, J10.8, J11.1, J11.8.
- Pneumonia (including influenza with pneumonia): J10.0, J11.0 and J12 to J18
- Other acute infections of the lower respiratory tract: J20 - J22.
The RIPS information from three public hospitals was analyzed, covering all patients within the subsidized system. The three hospitals correspond to increasing levels of complexity: San Cristobal Hospital (first healthcare level), San Blas Hospital (second healthcare level) and La Victoria Hospital (third healthcare level) (17).
The total size of the subsidized population of the studied age groups was calculated from estimations provided by the National Bureau of Statistics [Departamento Administrativo Nacional de Estadística] in 2012 (16,17). For both age groups, the burden of disease caused by ARIs was assessed using RIPS databases and the definition of burden of disease was restricted to the related morbidity and mortality of ARIs, and related ambulatory and hospitalized cases.
Using these individual patient records, the ICD-10 codes, the predefined time period and target population, patients with an ambulatory episode or hospitalization in one of the three hospitals were selected. The mortality rates for both groups caused by ARIs were estimated based on the mortality database of Bogotá’s Health Services taking into account, for example, unspecified pneumonia as the main cause of death (25,26).
Direct medical costs caused by the disease include costs of visits, drugs and diagnostic tests. The number of visits could be derived from RIPS. Treatment procedure was taken from national guidelines and costs from the hospital standard procedure cost (27,28). Ambulatory cases were categorized in two groups: the first group. ARIs cases excluding pneumonias, it was assumed that both age groups were treated with antipyretics; the second group, including all causes of pneumonia, consisted of ICD 10 codes (J10.0, J11.0 and J12 to J18). It was also assumed that, for both age groups, diagnosis was obtained through thorax X-ray and patients were treated with antipyretics and antibiotics. The average cost per treatment for each age group and healthcare level was estimated.
Data about hospitalizations, administered treatments and related direct costs (diagnostic, treatment, pharmaceutical and medical devices costs) registered in RIPS and retrieved for analysis were used to calculate the average cost per patient. The cost of treatment items included bed-cost per day, the physician’s salary, oxygen therapy and the cost of the Intensive Care Unit if applicable. The pharmaceutical cost included the different costs of antibiotics, antipyretics, nebulized bronchodilator therapies and other medications.
In order to compare the different costs by year, all costs were converted to real prices in 2008. To convert nominal prices of a specific year during the period between 2008 and 2012 into real prices, the cumulative inflation rate from 2008 until a specific year was applied (29). Colombian pesos were then converted to international dollars Int$, using the purchasing power parity from the International Monetary Fund (30,31).
In the temperate climate of the northern hemisphere, ARIs have a clear seasonal peak during winter (32,33). In this study, a consistent epidemiological peak in April, which historically is the rainiest month, was observed in children (32). The epidemiological peak is less pronounced (Figure 1.b) in senior population. During the pandemic A (H1N1) of 2009, the epidemiological peak emerged earlier in September and was more evident (Figure 1) in both age groups.
Children of the subsidized regime presented an ambulatory incidence between 54.4 % in 2012 and 66.3 % in 2009 (Table 1). Seniors of the subsidized regime presented an ambulatory incidence between 7.6 % in 2008 and 10.0 % in 2010 (Table 1). A hospitalization rate between 9.2 % in 2010 and 12.3 % in 2012 (Table 1) was identified for children, and between 0.6 % in 2008 and 2.1 % in 2012 for seniors (Table 1). The death rate varied between 18.1 deaths and 27.7 deaths per 100,000 children in 2010 and 2012, respectively, and for seniors, death rate ranged between 8.9 deaths and 47.8 deaths per 100,000 for the years 2008 and 2011, respectively (Table 1).
For children, the average cost per ambulatory ARIs, excluding pneumonias, was estimated between Int$ 15.6 in 2012 and Int$ 26.9 in 2009. The average cost per ambulatory ARIs for all pneumonias was estimated between Int$ 45.2 in 2012 and Int$ 60.8 in 2009. For all ambulatory cases, a total cost per year was estimated between Int$ 209,174 in 2011 and Int$ 284.570 in 2009. It was observed that the maximum value for the total cost occurred in 2009, during the influenza pandemic of A (H1N1).
For seniors, the average cost per ambulatory ARI episode, excluding pneumonias, was estimated between Int$ 15.5 in 2012 and Int$ 24.9 in 2009. The average cost per episode for all pneumonias was estimated between Int$ 43.0 in 2012 and Int$ 71.7 in 2008. For all ambulatory cases. a total cost per year was estimated between Int$ 29.631 in 2008 and Int$ 46.774 in 2010. The average cost incurred per hospitalized child due to ARIs in first healthcare level hospitals was estimated between Int$ 228.5 in 2009 and Int$ 280.5 in 2012. In second healthcare level hospitals. the average cost per hospitalized patient was estimated between Int$ 717.8 in 2012 and Int$ 785.6 in 2008. Finally. in third healthcare level hospitals. the average was estimated between Int$ 1.067.5 in 2010 and Int$ 1.492 in 2011 (Table 2). The total amount for the three hospitals was estimated per year between Int$ 1.334.352 in 2010 and Int$ 2.139.597 in 2011 (Table 2).
For seniors hospitalized due to ARIs at first healthcare level hospitals, the average cost per patient was estimated between Int$528, 2 in 2010 and Int$582, 8 in 2008. For second healthcare level hospitals, the average cost per patient was estimated between Int$887, 1 in 2009 and Int$1,130in 2012. At the third healthcare level hospitals, the average was estimated between Int$ 1,352.5 in 2012 and Int$2,440.5 in 2010 (Table 3). For the three hospitals, the total cost per year was estimated between Int$88,957 in 2008 and Int$373,382 in 2012 (Table 3).
Few studies have been conducted to calculate the average cost or yearly direct medical cost caused by ARIs. To the extent of our knowledge, this is the first study that correlates direct economic costs to an epidemiological burden in Colombia.
For both age groups, we observed that the incidence of ambulatory ARI episodes followed a seasonal pattern with one peak corresponding to the rainy period in April (Figure 1). This seasonal pattern offers us trustful consistency of the data. Furthermore, the yearly incidence of ambulatory cases for both age groups has a decreasing trend over the study period, especially for children, reaching its lowest level in 2012 (Table 1). Regarding yearly hospitalization rates, an increase in both age groups was noticed, reaching a maximum rate in 2012 for children (Table 1), for whom an overall increase in mortality rate at the district level with a value of 27.7 per 100,000 children was found. This value is higher than the national level of 13.45 per 100,000 children in 2012 (13, 26). In the subsidized population, the mortality rate may be more relevant due to a higher presence of risk factors. In seniors, the trend in the number of ambulatory cases and deaths is not clear probably because of the presence of co-morbidities.
In hospitalization cases, there is an increasing trend in the average and yearly total cost for both age groups, reaching a maximum level for children, in 2011 and for seniors in 2012; these costs increases are driven by the tertiary healthcare level.
Regarding hospitalization costs, compared to other national studies with children, we can see that our results of hospitalized pneumonia costs are close to the findings of Santamaria et al., of Int $1,525.3 (34) and Castaneda-Orjuela et al. of USD $1,175 (9). For seniors, our results of hospitalized cases are consistent with the ones by Ordonez et al. of USD $1,932 (35).
Taking into account only the subsidized population is a limitation of these results, as well as the use of administrative data. ARI cases were selected based on the ICD-10 registration in the RIPS database and the records of cause of death in the mortality database, nonetheless, the strength of the administrative data is the inclusion of all subsidized population. A further limitation is that, for ambulatory cases, the average cost was calculated based on national medical protocols and not on patient records, which underestimates the direct ambulatory cost. To simplify our findings for the hospitalized costs, we calculated the average cost, which limited the statistical distribution of the data. Also, direct medical and indirect costs spent by households were not considered since these costs could represent a high economic burden for households.
In order to diminish the impact of ARIs and other diseases caused by pneumococcus and seasonal influenza viruses. Colombia introduced a Pneumococcal Conjugated Vaccine in 2009 for children (37). Similarly, the seasonal influenza vaccine was included in 2009 in the national immunization schedules for children under 60 months old (38). For population aged 60 and older, the influenza vaccine was introduced in 2009 (38) and the pneumococcal polysaccharide vaccine in 2011 (10).
Despite the introduction of these vaccines, increases in hospitalization rates, mortality rates and related direct medical costs due to ARI in these two age groups were observed. Our analyses require better surveillance data in order to typify the pathogens that cause the disease burden of ARIs. Additional studies are also needed to provide a better understanding of the immunization campaigns including effectiveness, vaccines serotype coverage and timeliness.
Finally, socioeconomic factors could contribute to the observed increases in severity and mortality due to ARIs. The increases in the severity in children could be explained by the high percentage of young mothers with limited education and inadequate knowledge of prenatal and neonatal care (17,22). In this community, there are administrative and geographical barriers that could impede access to health facilities and treatments; the households could avoid bringing patients to health providers due to transportation costs and inadequate housing and sanitary conditions could also exacerbate the increase in severity of ARIs. In addition, San Cristobal district has experienced increases in rainfall levels in the past years, which may also explain the increases in severity of ARI. Other factors, such as malnutrition in children, passive smoking and air pollution, may also be involved in the increase of the severity of ARIs.
Direct medical costs of ARI represent an important economic burden on the subsidized health system of this community. The low-income stratum experiences a higher economic and disease burden than the national average stratum. Our findings highlight the need for further studies in the introduction of new vaccination strategies and evaluation of social, economic and environmental indicators related to economic and disease burden of ARI ♦
Conflicts of interests: None.
1. Murray CJ, Vos T, Lozano R, Naghavi M, Flaxman AD, Michaud C, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2197-223.
2. Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2095-128.
3. World Health Organization. Initiative for Vaccine Research (IVR) Acute respiratory infections [Internet]. 2013. Available from: http://apps.who.int/vaccine_research/diseases/ari/en/. Cited 2014 Feb 02.
4. Li S, Leader S. Economic burden and absenteeism from influenza-like illness in healthy households with children (5-17 years) in the US. Respir Med. 2007;101(6):1244-50.
5. Ministerio de Salud y Protección Social, Instituto Nacional de Salud, República de Colombia. Protocolo de vigilancia en Salud Pública Infección Respiratoria Aguda (IRA), Subdirección de Prevención Vigilancia y Control en Salud Pública; 2016.
6. Alvis-Guzman N, de la Hoz Restrepo F, Higuera AB, Pastor D, Di Fabio JL. The economic costs of pneumonia in children under 2 years of age in Colombia. Rev Panam Salud Publica. 2005;17(3):178-83.
7. Ministerio de Salud y Protección Social, República de Colombia. Infecciones Respiratorias Agudas (IRA) [Internet]. 2013. Available from: https://www.minsalud.gov.co/salud/Paginas/Infecciones-Respiratorias-Agudas-(IRA).aspx. Cited 2014 Feb 2014.
8. Buzzo AR, Roberts C, Mollinedo LG, Quevedo JM, Casas GL, Soldevilla JM. Morbidity and mortality of pneumonia in Ederlies in six Latin American countries. Int J Infect Dis. 2013;17(9):e673-7.
9. Castaneda-Orjuela C, Alvis-Guzman N, Velandia-Gonzalez M, De la Hoz-Restrepo F. Cost-effectiveness of pneumococcal conjugate vaccines of 7, 10, and 13 valences in Colombian children. Vaccine. 2012;30(11):1936-43.
10. Castaneda-Orjuela C, Alvis-Guzman N, Paternina AJ, De la Hoz-Restrepo F. Cost-effectiveness of the introduction of the pneumococcal polysaccharide vaccine in elderly Colombian population. Vaccine. 2011;29(44):7644-50.
11. Porras-Ramirez A, Alvis-Guzman N, Rico-Mendoza A, Alvis-Estrada L, Castaneda-Orjuela CA, Velandia-Gonzalez MP, et al. [Cost effectiveness of influenza vaccination in children under 2 years old and elderly in Colombia]. Rev Salud Pública (Bogotá). 2009;11(5):689-99.
12. Alvis-Guzman N, Orozco-Africano J, Paternina-Caicedo A, Coronell-Rodriguez W, Alvis-Estrada L, Jervis-Jalabe D, et al. Treatment costs of diarrheal disease and all-cause pneumonia among children under-5 years of age in Colombia. Vaccine. 2013;31 Suppl 3:C58-62.
13. Fundación Santa Fe de Bogotá, Seguimiento al Sector Salud en Colombia, Así vamos en salud. Tasa de Mortalidad por Infección Respiratoria Aguda (IRA) en menores de 5 años [Internet]. 2009 .Available from: http://www.asivamosensalud.org/inidicadores/estado-de-salud/grafica.ver/11. Cited 2014 Feb 02.
14. Nair H, Brooks WA, Katz M, Roca A, Berkley JA, Madhi SA, et al. Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis. Lancet. 2011;378(9807):1917-30.
15. Peasah SK, Azziz-Baumgartner E, Breese J, Meltzer MI, Widdowson MA. Influenza cost and cost-effectiveness studies globally - A review. Vaccine. 2013;31(46):5339-48.
16. Empresa Social del Estado Hospital San Cristóbal. Diagnóstico local en salud con participación social 2011 localidad cuarta San Cristóbal, Bogotá D.C.; 2012.
17. Empresa Social del Estado Hospital San Cristóbal. Diagnóstico local en salud con participación social 2012 localidad cuarta San Cristóbal, Bogotá D.C.; 2013.
18. Secretaría de Hacienda Distrital, República de Colombia. Ingresos, gastos y exclusión social en Bogotá, Serie de Equidad y Bienestar No 8, Bogotá D.C.; 2006.
19. Ministerio de Trabajo Decreto, República de Colombia. Decreto número 4919 de 2011: salario mínimo mensual legal [Internet]. 2013. Available from: http://www.mintrabajo.gov.co/empleo/abece-del-salario-minimo.html. Cited 2014 Feb 02.
20. Guerrero R, Gallego AI, Becerril-Montekio V, Vasquez J. [The health system of Colombia]. Salud Publica Mex. 2011;53 Suppl 2:s144-55.
21. Herrera D, de la Hoz F, Velandia M. Severe respiratory disease and its relationship with respiratory viruses in Colombia. Int J Infect Dis. 2008;12(2):139-42
22. PROFAMILIA. Encuesta distrital de demografía y salud Bogotá D.C.;2011.
23. Ministerio de Salud y Protección Social, República de Colombia. Lineamientos técnicos para el registro de los datos del registro individual de la prestación de servicios de salud RIPS [Internet]. 2009. Available from: http://www.minsalud.gov.co/Lineamientos/Lineamientost%C3%A9cnicosIPS.pdf. Cited 2014 Feb 02.
24. World Health Organization. International Statistical Classification of Diseases and Related Health Problems 10th revision (ICD-10) Version for; 2016, Chapter X Diseases of the respiratory system (J00-J99) 2010 [Internet]. 2016. Available from: http://apps.who.int/classifications/icd10/browse/2016/en#/X. Cited 2014 Feb 02.
25. Empresa Social del Estado Hospital San Cristóbal. Anuario epidemiológico local 2011 San Cristóbal, Bogotá D.C.; 2011.
26. Empresa Social del Estado Hospital San Cristóbal. Anuario epidemiológico local 2012 San Cristóbal, Bogotá D.C.; 2012.
27. Secretaria distrital de salud de Bogotá. Guía de promoción y atención en Enfermedad Respiratoria Aguda (ERA), Bogotá D.C.; 2012.
28. Secretaria distrital de salud de Bogotá. Neumonía adquirida en la comunidad, Bogotá D.C.; 2011.
29. World Bank. Inflation, GDP deflator (annual %) [Internet]. 2013. Available from: http://data.worldbank.org/indicator/NY.GDP.DEFL.KD.ZG. Cited 2014 Feb 02.
30. World Health Organization. WHO guide for standardization of economic evaluations of immunization programmes [Internet]. 2008. Available from: http://apps.who.int/iris/bitstream/10665/69981/1/WHO_IVB_08.14_eng.pdf. Cited 2014 Feb 02.
31. International Monetary Fund. World Economic Outlook Database, October 2013 [Internet]. Available from: http://www.imf.org/external/pubs/ft/weo/2013/02/weodata/weoselgr.aspx. Cited 2014 Feb 02.
32. Tamerius JD, Shaman J, Alonso WJ, Bloom-Feshbach K, Uejio CK, Comrie A, et al. Environmental predictors of seasonal influenza epidemics across temperate and tropical climates. PLoS Pathog. 2013;9(3):e1003194.
33. Shek LP, Lee BW. Epidemiology and seasonality of respiratory tract virus infections in the tropics. Paediatr Respir Rev. 2003;4(2):105-11.
34. Santamaría M, Fabían G, Uribe MJ. Fedesarrollo, Bogotá D.C.; 2008.
35. Ordonez JE, Orozco JJ. Cost-effectiveness analysis of pneumococcal conjugate vaccine 13-valent in older Ederlies in Colombia. BMC infectious diseases. 2014;14:172.
36. Parra EL, De La Hoz F, Diaz PL, Sanabria O, Realpe ME, Moreno J. Changes in Streptococcus pneumoniae serotype distribution in invasive disease and nasopharyngeal carriage after the heptavalent pneumococcal conjugate vaccine introduction in Bogotá, Colombia. Vaccine. 2013;31(37):4033-8.
37. Ordonez JE, Orozco JJ. Cost-effectiveness analysis of the available pneumococcal conjugated vaccines for children under five years in Colombia. Cost Eff Resour Alloc. 2015;13:6.
38. Ministerio de Salud y Protección Social, República de Colombia. Logros y futuros en Vacunación contra los virus respiratorias [Internet]. 2012. Available from: http://www.sabin.org/sites/sabin.org/files/JacquelinePalaciosGonzalez.pdf. Cited 2014 Feb 02.