MVA85A (modified vaccinia Ankara 85A) is a
vaccine against tuberculosis developed by researchers led by Professor
Helen McShane at
Oxford University
The University of Oxford is a collegiate research university in Oxford, England. There is evidence of teaching as early as 1096, making it the oldest university in the English-speaking world and the second-oldest continuously operating u ...
. It is a
viral vector vaccine and consists of an
MVA virus engineered to express the 85A antigen once it infects a host cell. 85A is a cell-wall protein of the
tuberculosis bacillus.
This vaccine produces higher levels of long-lasting cellular immunity when used together with the older TB vaccine
BCG. Phase I clinical trials were completed in 2008 and then phase II clinical trials took place in
South Africa
South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...
. Efficacy trials ran in parallel from 2009 to 2019. Results released in February 2013 were described as "disappointing", showing only a
statistically insignificant prevention rate in infants. A summary of animal studies published in 2015 cast doubt on the efficacy of the vaccine.
In 2018, a
''BMJ'' investigation raised concerns about the ethics of an efficacy trial in South African infants, particularly because of results from earlier animal trials such as a study with
macaque
The macaques () constitute a genus (''Macaca'') of gregarious Old World monkeys of the subfamily Cercopithecinae. The 23 species of macaques inhabit ranges throughout Asia, North Africa, and Europe (in Gibraltar). Macaques are principally f ...
s at
Porton Down. One response argued that 14 prior human trials showed a safety signal, that regulators were aware of the primate trial and decided to continue, and that three subsequent investigations found no evidence of wrong-doing. Another response by
Ian Orme questioned the critique of animal models.
A Cochrane review in 2019 concluded that MVA85A is safe, however it is not effective in preventing TB infection either on its own or in combination with BCG.
References
External links
New TB vaccine shown to be safe
Tuberculosis vaccines
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