Testing the RTS/S malaria vaccine in Malawi
The world’s largest clinical trial of an experimental malaria vaccine, largely funded by the Bill & Melinda Gates Foundation in partnership with the vaccine maker GlaxoSmithKline, has produced disappointing results – again.
It shouldn’t be too surprising.
The study has been producing the same disappointing results for many years now. It’s just been emphasized as progress before, with those supporting the work at the Gates Foundation and at the PATH Malaria Vaccine Initiative usually characterizing the vaccine’s protection rate of about 30 percent as proof of concept or as an encouraging step forward.
For example, here’s a Google News shot of how last year’s similar findings — of 30 percent protection — were characterized in the media:
Google News on the malaria vaccine
These stories were over-the-top, so I felt compelled to write Three Reasons Why We Should Not Get So Excited.
On the flip side of that coin, maybe we shouldn’t be too disappointed now.
The findings last year were no breakthrough. This vaccine, called RTS,S, was tested in adults 30 years ago and showed little efficacy. It was modified for use in children and, over the past decade or so of testing in Africa, continues to show minimal immune response. Here’s a story I wrote for the Seattle PI in 2007 in which the researchers (five years ago) reported 30 percent protection against disease.
So why were pretty much these same disappointing results last year hailed as a breakthrough?
I attribute this in part to the Kumbaya effect.
The Gates Foundation and PATH have put more than $200 million into this study and, well, both organizations tend to like ‘success stories.’ At the Seattle malaria forum where the results on RTS,S were announced last year, there were calls by Bill and Melinda Gates for ‘urgent optimism’ and the GlaxoSmithKline vaccine was hailed as a reason for such optimism.
I talked to many of the attendees who dutifully said optimistic things in public but privately said Glaxo’s vaccine will never work clinically. Interesting science, sure, but it won’t be of much use in the field.
Now, with similar findings this time in babies (last year’s results were from testing the vaccine in toddlers), most are reporting the fairly consistent 30 percent protection rate for this experimental vaccine as disappointing or frustrating. Yet nothing much has really changed, other than the media’s characterization of the study.
(NOTE: The results last year were variously reported as showing the vaccine achieved more than 50 percent protection, but a close reading of the 2011 results showed the vaccine’s efficacy was indeed more like 30 percent with no impact on mortality.)
What these results show, again, is of scientific value. They show a malaria vaccine is possible. What they also show is that it probably won’t be Glaxo’s RTS,S vaccine that makes it into wide use due to how weak an immune response it produces. It’s not a breakthrough, but it’s not nothing either.
Here’s what Bill Gates, the urgent and impatient optimist, had to say about it:
“This is an important scientific milestone and needs more study,” said Bill Gates, co- founder of the Bill & Melinda Gates Foundation. “The efficacy came back lower than we had hoped, but developing a vaccine against a parasite is a very hard thing to do. The trial is continuing and we look forward to getting more data to help determine whether and how to deploy this vaccine.”
Bill’s right. Getting a vaccine to work even a little against this parasite is a sign of progress. Malaria is, after all, way more complex than your average germ. Malaria has more than 5,000 genes. The AIDS virus, HIV, has nine genes. The flu virus, a dozen or so. Bacteria have something like 500 genes on average.
Malaria is more like a tricky little creature than it is like other disease-causing agents.
The RTS,S vaccine may not ever end up being good enough for routine use against malaria in the clinic. But it’s important to remember that a decade or so back, few were even working on a malaria vaccine. Now, we can at least celebrate the fits and starts of an active scientific exploration.
