Malaria vaccine test results disappoint
Scientists testing malaria vaccine on children in Kenya find its effect is reduced over time but say it still prevents many cases
Optimism over the new malaria vaccine being tested in Africa could be set to fall after results suggested its effect could reduce over time and that it disappears fastest in children who are most exposed to malarial mosquito bites.
But the tests follow a string of disappointing results, which have clearly shown how difficult it is to make a vaccine to protect against the disease, which kills more than 650,000 children, most of them very young, a year.
Last year a large-scale phase III trial showed that the vaccine saved only a third of babies aged six to 12 weeks old from falling ill. This is the age group that the vaccine is intended for, but the protection was lower than that which appeared in older children.
"The efficacy came back lower than we had hoped, but developing a vaccine against a parasite is a very hard thing to do," said Bill Gates, co-founder of the Bill & Melinda Gates Foundation and one of the research funders, at the time."
The marginal results could have been predictable from several medical phenomenon.
First, some of these babies were probably breast fed by their mothers and had "clostrum antibodies" to malaria circulating in their blood. These are passive antibodies that all mammals pass to their young to provide some inherent protection to an otherwise "naïve" (unexposed and unvaccinated) host. It is the same reason why livestock and pets have to nurse almost immediately to get protection against common bacteria around them. So some of these babies probably came from mothers with varying levels of antibodies to malaria that passed to the babies. What does that do? The first vaccination with the malaria vaccine is neutralized by the passive antibody circulating in the babies blood. So at best, there is a fraction of the intended immunizing dose that is successfully administered. But it removes any antibody from protecting the baby from a mosquito borne malaria exposure. That phenomenon alone could lower the benefits of vaccination significantly. The vaccinated babies would have to be kept in isolation to determine the maximum effect of the vaccine.
Second, the first study by GSK was a multiple vaccine study. They attempted to give malaria along with Hep B and DPT in one vaccination. That approach dilutes out the immune system's response to any one vaccine. Fortunately, they then focused on malaria alone in the second study.
This brings us to point 3. If the GSK study was performed by an intramuscular injection, this is where Inovio has the edge. The malaria vaccine would be injected intracellularly by the electorporation technology. The circulating passive antibodies would not react with the dose of the vaccine because it would largely be intracellular and protected by the cell membrane from any circulating antibody.
Now the only questions are what is the best anatomical site on a baby to vaccinate and when?
A reminder about Inovio and its partership with PATH Malaria of Bill & Melinda Gates Foundation:
PATH is partnering with Inovio Pharmaceuticals Inc. to work on the global health organization’s Malaria Vaccine Initiative.
Blue Bell, Penn.-based Inovio will be working with PATH Malaria Vaccine Initiative (MVI) on a follow-on project to develop an effective malaria vaccine and new technologies for delivering vaccinations.
Researchers are investigating whether a new method for delivering vaccines, called electroporation, could boost the immune response to better protect people from malaria infections.
The approach is completely different from the RTS,S vaccine, which was first announced in November 2011 and which has received tremendous support from The Bill & Melinda Gates Foundation. At the time, RTS,S was found to reduce the risk of clinical malaria by 56 percent, and severe malaria by 47 percent. Since then, RTS,S has been found to be less effective in children younger than 3, with only about 30 percent efficacy.
Malaria is a parasite that kills more than 500,000 children younger than age 5 every year."
Could the aforementioned "tremendous support" of PATH moves from GSK to Inovio's Malaria vaccine trials, after the disappointing results of GSK (RTS,S) vaccine?
Another info we should keep in mind is that the RTS,S vaccine was "fast tracked" -with the help of PATH of course...- .
According to what deliveryman wrote, Inovio's Malaria vaccine is a strong candidate to be highly funded by PATH Malaria and perhaps fast tracked as the 33% protection rate of RTS,S is better than nothing, but not enough to satisfy anyone, especially Bill Gates...