Three reasons not to get too excited about the Gates-Glaxo malaria vaccine | 

Last week, the biggest news out of the Gates Foundation’s Malaria Forum were some interim results of an ongoing test of an experimental malaria vaccine.

Many, if not most, media reported the findings in somewhat hyperbolic fashion as a “major milestone,” a “breakthrough” or “world’s first malaria vaccine.”

Google News on the malaria vaccine

Despite the hype and fanfare, many experts at the Seattle meeting said this experimental vaccine (known as RTS,S) actually so far represents only incremental progress — a scientific achievement which may still turn out to have little practical utility in the real world. They usually only said so privately, given that the Gates Foundation preferred to hear “optimistic” assessments rather than cranky ones.

1. No breakthrough. Let’s first put to bed the claims that these findings represent a major milestone. In fact, the findings largely repeat earlier ‘interim’ results that have continued to find the vaccine protects only half of those immunized — and appears to wane fairly rapidly over time.

So that’s the first reason — a point also made in this (terribly titled) Huffington Post article A vaccine that works only half the time is not the shot in the arm malaria needs. The author, Tido von Schoen-Angerer, director of Médecins Sans Frontières‘ essential medicines campaign says:

But while the latest advance toward the development is scientifically important, there are several reasons to be cautious about the difference this vaccine could make, on the basis of current results.

2. The cost question. The second reason this halfway effective malaria vaccine may not work is cost. The manufacturer GlaxoSmithKline has refused to say what it thinks it will have to charge for the vaccine, other than to say it would be “at cost” plus 5 percent. Neither the PATH Malaria Vaccine Initiative, which is working with GSK on the malaria vaccine trial, or the Gates Foundation (which funds the PATH initiative) will say what price they think is feasible. Many say anything over a dollar might be too much for poor countries.

3. The science. It is promising that researchers have shown a vaccine against malaria is possible. But there’s a lot of other research out there indicating why it may be quite difficult to get a malaria vaccine that can perform as well as most of us expect a vaccine to perform — providing ideally something like 90 percent protection but hopefully not lower than 70 percent.

The malaria parasite is not a virus with a dozen genes but basically a little critter with some 5,000 genes (humans have about 25,000) and has a lot of different options for evolving — resisting drugs or perhaps vaccines. Some new studies suggest other versions of the parasite that infect apes and chimps may be evolving the capacity to infect humans.

The RTS,S study published in the New England Journal of Medicine noted that the vaccine was less protective (about 30 percent) against severe malaria in children and found no statistical difference in malaria mortality between those vaccinated and those not vaccinated. In addition, children getting the vaccine had a higher rate of seizures.

This vaccine, the RTS,S vaccine, has been around a long time, nearly 30 years. It had been shelved for failing to protect adults against malaria. Refinements (new adjuvants) have made it modestly effective in children, which offers the promise of eventually finding an effective vaccine against this deadly killer.

All this is why it’s a bit off-target to be calling RTS,S a breakthrough or major milestone. It may never become the “world’s first malaria vaccine.” That title probably should be reserved for an approved vaccine — just as in 2009 an experimental AIDS vaccine that showed 30 percent effectiveness is not yet the world’s first AIDS vaccine.

 

  • Anonymous

    Humans naturally produce antibodies when exposed to Malaria.  The problem is that the antibodies are specific to the particular parasite that infects each human.  But there are several species of parasite, and immunity to one does not translate into immunity against another.  The parasites live in the same geographies and they get around.  A vaccine that immunizes against only one parasite will not protect against the others, so the patient eventually gets re-infected by another strain.