jueves, 2 de octubre de 2014

Vacuna contra la tuberculosis que solo es efectiva contra la infección en latitudes específicas

Vacuna contra la tuberculosis que solo es efectiva contra la infección en latitudes específicas

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Vacuna contra la tuberculosis que solo es efectiva contra la infección en latitudes específicas

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Durante muchas décadas ha existido una vacuna que protege contra la enfermedad de la tuberculosis (TB). Pero hasta ahora no había evidencia de si la vacuna también prevenía la infección por TB. Un metaanálisis realizado por investigadores británicos que se publicó en "The BMJ" muestra que la inmunización es efectiva contra la infección, aunque solo en latitudes específicas.
En el análisis realizado por University College London, se incluyeron 14 estudios con 3855 participantes de 9 países diferentes, que se llevaron a cabo entre 1950 y 2013. El estudio se centró en la eficacia protectora de la vacuna contra la infección.
En general, los científicos hallaron que la inmunización tuvo una efectividad del 19 por ciento en niños vacunados comparados con niños no vacunados. Sin embargo, análisis más detallados revelaron que los estudios realizados en países por encima de los 40 grados de latitud mostraron una efectividad del 26 por ciento contra la infección, mientras que no se halló evidencia de efecto protector en países en latitudes por debajo de los 40 grados.
El autor principal Ibrahim Abubakar dijo que el efecto de la vacunación difiere en países con tasas altas y bajas de tuberculosis. El uso de la vacunación fue, de todos modos, "razonable", aunque investigaciones futuras sobre los candidatos a las vacunas deben investigar en más detalle la eficacia contra la infección.

Effect of BCG vaccination against Mycobacterium tuberculosisinfection in children: systematic review and meta-analysis

BMJ 2014349 doi: http://dx.doi.org/10.1136/bmj.g4643 (Published 05 August 2014)Cite this as: BMJ 2014;349:g4643
  1. A Roy, senior scientist1
  2. M Eisenhut, consultant paediatrician2
  3. R J Harris, statistician1
  4. L C Rodrigues, professor of epidemiology3
  5. S Sridhar, research associate4
  6. S Habermann, junior doctor2
  7. L Snell, junior doctor2
  8. P Mangtani, senior lecturer3
  9. I Adetifa, paediatrician and medical epidemiologist5
  10. A Lalvani, professor of infectious disease4
  11. I Abubakar, professor of infectious disease epidemiology16
    Author affiliations
  1. Correspondence to: I Abubakar i.abubakar@ucl.ac.uk
  • Accepted 11 July 2014


Objectives To determine whether BCG vaccination protects against Mycobacterium tuberculosis infection as assessed by interferon γ release assays (IGRA) in children.
Design Systematic review and meta-analysis. Searches of electronic databases 1950 to November 2013, checking of reference lists, hand searching of journals, and contact with experts.
Setting Community congregate settings and households.
Inclusion criteria Vaccinated and unvaccinated children aged under 16 with known recent exposure to patients with pulmonary tuberculosis. Children were screened for infection with M tuberculosis with interferon γ release assays.
Data extraction Study results relating to diagnostic accuracy were extracted and risk estimates were combined with random effects meta-analysis.
Results The primary analysis included 14 studies and 3855 participants. The estimated overall risk ratio was 0.81 (95% confidence interval 0.71 to 0.92), indicating a protective efficacy of 19% against infection among vaccinated children after exposure compared with unvaccinated children. The observed protection was similar when estimated with the two types of interferon γ release assays (ELISpot or QuantiFERON). Restriction of the analysis to the six studies (n=1745) with information on progression to active tuberculosis at the time of screening showed protection against infection of 27% (risk ratio 0.73, 0.61 to 0.87) compared with 71% (0.29, 0.15 to 0.58) against active tuberculosis. Among those infected, protection against progression to disease was 58% (0.42, 0.23 to 0.77).
Conclusions BCG protects against M tuberculosis infection as well as progression from infection to disease.
Trial registration PROSPERO registration No CRD42011001698 (www.crd.york.ac.uk/prospero/).


Cite this as: BMJ 2014;349:g4643


  • Contributors: AR and ME contributed equally to the work. IA, ME, and AR conceived idea and designed the study. AR and ME acquired the data. SH and LS contributed to the literature search and quality assessment. RJH was responsible for the statistical analysis. RJH, IA, ME, AR, PM, LCR, and AL analysed and interpreted the data. ME and AR drafted the manuscript. All authors contributed to planning, interpretation and writing of the manuscript and critically revised the manuscript for intellectual content. IA is guarantor.
  • Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. IA is supported by the UK National Institute for Health Research and the UK MRC.
  • Competing interests: All authors have completed the ICMJE uniform disclosure form atwww.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; AL is inventor for several patents underpinning T cell based diagnosis. The ESAT-6/CFP-10 IFN-gamma ELISpot was commercialised by an Oxford University spin-out company (T-SPOT.TB, Oxford Immunotec, Abingdon, UK), in which Oxford University and AL have minority shares of equity and entitlement to royalties.
  • Ethical approval: Not required.
  • Declaration of transparency: IA affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
  • Data sharing: Technical appendix, statistical code, and dataset are available from IA.
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/.


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