FA al-Kassimi, MS al-Hajjaj, IO al-Orainey and EA Bamgboye
Medical Department, College of Medicine, King Saud University, Riyadh, Saudi Arabia.

A case-control study was conducted in Saudi Arabia, where the same strain of BCG has been used and surveys had shown that up to 88% of vaccinated children remain tuberculin negative. Active cases were obtained by surveying the seven tuberculosis centers in 1 yr. Control subjects were obtained from a nationwide survey of normal individuals. Vaccination in both groups was ascertained by history and BCG scar. Relative risk of contracting active tuberculosis in the vaccinated versus unvaccinated and protection was calculated. Protection was as follows: age group 5 to 14 yr, 82% (55 to 93%); age group 15 to 24 yr, 67% (55 to 77%); and age group 25 to 34 yr, 20% (-6 to 37%). We document the uninterrupted record of protection by BCG administered in the neonatal period and discuss the significance of vaccination timing. We concur with other studies that protection lapsed after about 20 yr. More importantly, this is the first large study that documents a lack of tuberculin sensitivity despite protection. This challenges the view that sensitization is essential for protection and supports the "two- pathway" theory that BCG vaccination could trigger either protective (Lister type) or antagonistic (tuberculin or Koch type) reactions and that the most protective vaccines would have little tuberculin- sensitizing effect because the two pathways are competitive.

This article has been cited by other articles:

				B. R Diness, A. B Fisker, A. Roth, M. Yazdanbakhsh, E. Sartono, H. Whittle, J. E Nante, I. M Lisse, H. Ravn, A. Rodrigues, et al. Effect of high-dose vitamin A supplementation on the immune response to Bacille Calmette-Guerin vaccine Am. J. Clinical Nutrition, October 1, 2007; 86(4): 1152 - 1159. [Abstract] [Full Text] [PDF]

				J. Dietrich, R. Billeskov, T. M. Doherty, and P. Andersen Synergistic Effect of Bacillus Calmette Guerin and a Tuberculosis Subunit Vaccine in Cationic Liposomes: Increased Immunogenicity and Protection J. Immunol., March 15, 2007; 178(6): 3721 - 3730. [Abstract] [Full Text] [PDF]

				M. O. C. Ota, T. Goetghebuer, J. Vekemans, B. J. Okoko, M. J. Newport, K. P. W. J. McAdam, and A. Marchant Dissociation Between Tuberculin Skin Test and In Vitro IFN-{gamma} Responses Following Neonatal BCG Vaccination J Trop Pediatr, April 1, 2006; 52(2): 136 - 140. [Abstract] [Full Text] [PDF]

				B. Kampmann, G. N. Tena, S. Mzazi, B. Eley, D. B. Young, and M. Levin Novel Human In Vitro System for Evaluating Antimycobacterial Vaccines Infect. Immun., November 1, 2004; 72(11): 6401 - 6407. [Abstract] [Full Text] [PDF]

				G. H Bothamley, E. Cooper, D. Shingadia, and A. Mellanby Tuberculin testing before BCG vaccination BMJ, July 31, 2003; 327(7409): 243 - 244. [Full Text] [PDF]

				L. Brandt, J. Feino Cunha, A. Weinreich Olsen, B. Chilima, P. Hirsch, R. Appelberg, and P. Andersen Failure of the Mycobacterium bovis BCG Vaccine: Some Species of Environmental Mycobacteria Block Multiplication of BCG and Induction of Protective Immunity to Tuberculosis Infect. Immun., February 1, 2002; 70(2): 672 - 678. [Abstract] [Full Text] [PDF]

				M. P. Arbelaez, K. E Nelson, and A. Munoz BCG vaccine effectiveness in preventing tuberculosis and its interaction with human immunodeficiency virus infection Int. J. Epidemiol., December 1, 2000; 29(6): 1085 - 1091. [Abstract] [Full Text] [PDF]

				M. M. TALA-HEIKKILA, J. E. TUOMINEN, and E. O. J. TALA Bacillus Calmette-Guerin Revaccination Questionable with Low Tuberculosis Incidence Am. J. Respir. Crit. Care Med., April 1, 1998; 157(4): 1324 - 1327. [Abstract] [Full Text] [PDF]