Tuberculosis vaccine does not work



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06.02.2013

Researchers have been working on the development of a new vaccine against tuberculosis for decades. The BCG (Bacille Calmette-Guérin) vaccination used up to now shows an insufficient protective effect with a relatively high risk of side effects. The new combination vaccine MVA85A should help here, but researchers at Oxford University have now found that MVA85A could not improve the protective effects of BCG vaccination in children.

MVA85A was developed to improve the protective effect of BCG vaccination and was able to achieve convincing results in the first experiments on animals. The researchers around Dr. Michele Tameris of the South African Tuberculosis Vaccine Initiative in South Africa and Prof. Helen McShane of the University of Oxford have now carried out a comprehensive study to examine the "safety, immunogenicity and efficacy of MVA85A against tuberculosis and Mycobacterium tuberculosis infections in infants" and their results published in the specialist magazine "The Lancet". The researchers conclude that MVA85A is well tolerated in children but has no additional protective effect.

Previously ineffective tuberculosis vaccine and with a high risk of side effects The scientists examined whether the combination of MVA85A and BCG vaccination can improve vaccination protection in children. There was great hope that they would finally find a way to combat the weaknesses in BCG vaccination. Because this live vaccine developed from weakened bovine tubercle bacilli only protects against the most serious complications of tuberculosis infections, the so-called miliary tuberculosis and tuberculous meningitis (meningitis). The more widespread pulmonary tuberculosis, which may also be life-threatening, is not prevented by the vaccine. In Germany, the Standing Vaccination Commission (STIKO) withdrew the recommendation for BCG vaccination almost 15 years ago, since it does not protect against tuberculosis.

Vaccine tested on nearly 3,000 South African children The scientists led by Prof. Helen McShane and Dr. In her double-blind, placebo-controlled study, Michele Tameris has now investigated the effects of the new tuberculosis vaccine on 2,797 South African children aged four to six months who had previously received BCG vaccination. 1,399 infants received MVA85A and 1,398 children received a placebo. The researchers then observed up to 37 months what protective effect the vaccination had and what side effects occurred. The primary goal of the study was to assess safety (incidence of adverse and serious adverse events), McShane and Tameris write. The researchers found that while in the experimental group "more children than at least one local adverse event in the control group, the number of children with systemic adverse events or serious adverse events did not differ between the groups." They therefore go assume that MVA85A is well tolerated and does not significantly increase the risk of side effects.

Lack of effectiveness of the new tuberculosis vaccine Regarding the protective effect, the researchers found that the risk of infection in the test group was similar to that in the control group. The new vaccine therefore has almost no side effects, but also almost no protective effect. The researchers were unable to provide any further information on the "reasons for the lack of effectiveness of MVA85A against tuberculosis or M. tuberculosis infections in infants", but merely emphasized that this requires further research. Despite the disappointing results, a “terminal prognosis for MVA85A or for all other tuberculosis vaccines in development” cannot be given today, writes Christopher Dye of the World Health Organization (WHO) in a commentary on the current “Lancet” article. The search for an improved tuberculosis vaccine remains one of the great challenges of contemporary medical research. (fp)

Also read:
RKI warns of tuberculosis in Germany
Tuberculosis: the most dangerous infectious disease
Researcher: Tuberculosis over 500,000 years old?

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