No effective vaccine for the disease has yet been developed.

The experiment is the first step in a long process of developing an effective vaccine.

Development and testing of more effective vaccines is under way.

An effective vaccine is not yet available for malaria, although several are under development.

But no one is sure whether an effective vaccine will prove feasible.

"the greatest hope is in discovery of a safe and effective vaccine".

How many people would take such a risk from a partly effective vaccine?

Because in the end, there will be a more effective vaccine.

It could also accelerate the development of new drugs and an effective vaccine.

Yet no effective vaccine for malaria has so far been developed.