Efficacy and effectiveness of BCG are mostly debated since decades so the urgent need of a new TB vaccines.
To date, among 12 candidates in the pipeline, only one ( MVA85A ) has reached the phase 2b ( proof of concept ), with the disappointing resuls.
Is there any hope with the other candidates?
My evaluation of the possibility of having an efficacious TB vaccine with the actual candidates is very low. We have to accept the fact that for some disease/pathogens and with the present technology , development of an efficacious vaccine is not possible in short mid-term. I refer not only to TB but also HIV and Malaria, and other parasitic diseases. However, other tools are available to cure and control these diseases .
Yes, I think there is hope. The MVA-85A trial was a very high-risk trial, conducted in the hope of getting a rapid answer with regard to protection, so we should not read too much into its failure. Some researchers (including myself) accurately predicted the results of this trial (ie: no significant efficacy) before it even started. As it happens, the results in infants mimic almost exactly the earlier results in animal models, so even though it is a disappointment, it should not be a huge surprise.
The reason I discribe the trial as "high-risk" is that MVA-85A was given to infants in addition to BCG. The goal was to see if the vaccine could add extra value to BCG (which would be great) but BCG already has 70-80% efficacy in infants during the first years of life. That meant that the window to demonstrate efficacy was very small, and indeed, in the earlier animal testing of this vaccine, we had great difficulty demonstrating a significant effect on top of that from BCG.
However, as redcently discussed in the thread below, the problem is that BCG efficacy wanes with time. So it is quite possible (I would even say likely) that MVA-85A would perform better if used as a booster later in life when the protective effect of BCG is not so pronounced. That. however will require larger, longer-lasting trials.
So I think we should look at this trial as a hgh-risk attempt to rapidly generate proof of concept. There was always a high chance that this approach would fail, but it does not mean that the vaccine itself is fatally flawed: a more conservative trial design might well generate data showing efficacy.
https://www.researchgate.net/post/Is_there_any_scientific_evidence_that_BCG_vaccination_is_actually_beneficial?cp=re65_x_p2&ch=reg&loginT=oexMBcGtRtUDZi6D85Bnfqd6uqIaYCHvBL-o-H4RDBg%2A&pli=1
I agree with all of you. We learned from the MVA85A, but at present, it seems difficult to predict what would be the most promising vaccine.
Dear Dr. Elenge, can you please direct me to a publication about the MVA-85A results? I am currently preparing a paper discussing a new approach to vaccines for TB. I expect the reaction of the reviewers to be quite negative to my suggestions, and could use all the data I can find from current efforts.
Dear Dr Kevin, thanks for your comment. I also do a review on BCG vaccine and the need of novel TB vaccines. Please see in attach the result from the phase 2b of MVA85A.
http://www.sciencedirect.com/science/article/pii/S0140673613601774
I have hope in two live attenuated candidate vaccines:
MTBVAC developed by Dr Carlos Martín at the Zaragoza University, Spain. This a lab attenuated M. tuberculosis strains that lack two genes essential for virulence.
BCG ΔureC::hly developed by the team of Dr Kaufmann at the Max Planck in Berlin. This is BCG reinforced by the the expression of listeriolysin from Listeria monocytogenes. This gain of function allow a higher presentation of protective antigens in HLA class I context.
There many publications and articles in the web. Specially the TBVI site and StopTB site. In http://www.stoptb.org/wg/new_vaccines/documents.asp you will find a Road Map of clinical trials.
The only trial in Phase III is being performed in China with another live vaccine developed by a local company Anhui Zhifei Longcom Biopharmaceutical Co
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