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Usage of vaccines and therapeutics in public health emergencies 2
Published on February 27, 2020 39 min
A selection of talks on Infectious Diseases
An introduction to the world of microbes
- Dr. David Westenberg
- Missouri University of Science and Technology, USA
Welcome back to the second part of my talk on usage of vaccines and therapeutics in public health emergencies. In the second part of this talk, I will be covering specific tools like vaccine and therapeutics and mechanism of making those vaccines and therapeutics focused on Ebola outbreak.
This long list is actually all the clinical trials that were initiated in humans, mainly first in North America and Europe, and then after that in west Africa. Each one of them is not important per se. What's important is to show you all the work that was done about a year and a half at the same time as this outbreak was ongoing, all the work that was put into having those clinical trials to make sure that, at the minimum, the experimental drug and vaccine that were considered were at least safe and potency could be tested at the same time could be evaluated but at least there will be no harm coming from those vaccine and those therapeutics.
This slide is actually showing how one of the vaccine VSV-Ebola, was used to try to understand if the vaccine was potent and able to protect people. So you see a circle where the main individual in the middle is actually somebody that is found to be positive. So it's positive for Ebola infection and the strategy is what's called concentric circles. So it's to go and offer the vaccine and have had direct contact with that individual and to also offer the vaccine to people that have had contact with the second person if you want. So it's not only the direct contact, but it's the contact of the contacts that are offered a vaccine. So by using this design, which it wasn't new for the outbreak, it was a design that was used to eradicate completely smallpox and the last effort of smallpox vaccination were following the same strategy. So this was used also for the VSV-Ebola vaccine. It led to this first paper that associated vaccination with protection in humans. There was a lot of work that followed this. First, initial paper and no need to go through all of it, but just to mention that actually this is the only vaccine and has shown potency at protecting people against Ebola infection not because it is the only one working, but because it is the only one that had the chance to be in a clinical trial design that had allowed for the data to really lead to a conclusion of whether or not this vaccine was efficient. So other vaccine, for example, there's another Novartis base vaccine that was also evaluated in the phase three trials, but it did not have that strategy of doing contact and contact of contact and studied one to vaccinate the population on the largest scale and hoping that that will be what's calling attack rates so enough people to get infected to be able to conclude and compare a population that was vaccinated to a population that received the placebo or basically a sham vaccine. Other trials with that lethal virus did not have enough individual enrolled to lead to any conclusion. But the good news was that at least one vaccine shown protection in this outbreak the vaccine VSV.