The limits of Africa's malaria vaccine pilots

IBADAN, Nigeria — In the popular imagination, a disease can be eradicated once there is a vaccine for it — and sometimes this has proven to be true.

The United States successfully eliminated polio in 1979 after widespread vaccination efforts. Smallpox was also eradicated globally in 1980 following an immunization campaign led by the World Health Organization.

And so the launch in April of the world’s first malaria vaccine pilots — targeting 360,000 children a year across Ghana, Kenya, and Malawi — was heralded by many as the beginning of the end for a disease that kills around 400,000 people a year, mostly in sub-Saharan Africa.

But the reality is far less simple.

WHO itself, which greenlighted the piloting of GlaxoSmithKline’s RTS,S malaria vaccine in 2017, describes it as a complementary malaria control tool that will be added to the list of recommended measures for prevention. Those include routine use of insecticide-treated bed nets, indoor sprays, and rapid malaria testing and treatment.

On their own, these measures have been directly responsible for a dramatic reduction in malaria deaths. Between 2000-2013, malaria incidence rates decreased by an estimated 30% globally.

“We have seen tremendous gains from bed nets and other measures to control malaria in the last 15 years,” said WHO Director-General Tedros Adhanom Ghebreyesus in a statement. But he noted that progress has stalled and even reversed in some areas.

“We need new solutions to get the malaria response back on track, and this vaccine gives us a promising tool to get there,” he said, predicting that it could save tens of thousands of children’s lives.

But the limits are high. In clinical trials, it prevented 4 in every 10 cases of malaria, reducing the need for hospitalization by 40% and the need for blood transfusion by 30% — a great achievement, but not a miracle cure.

There will also be challenges in rolling out the vaccine — first among them, the dosage requirements. The vaccine needs an initial course of four injections over a period of around two years. It is then effective for four years after the final dose.

But experts believe that the number of children to complete the course will be much lower than the total number reached. “If millions of children are yet to receive a single dose vaccine that will protect them against life-threatening diseases, how many do you think will ... receive a vaccine four times?” asked Nigerian public health expert Dr. Ayobami Bakare.

There is also the ever-present question of cost. With each dose costing $5, it will cost $20 to fully immunize a child. A national immunization program would eat up a significant chunk of the health budget of most African countries, and would likely depend on the support of the Global Fund to Fight AIDS, Tuberculosis and Malaria and Gavi, the Vaccine Alliance. Both have provided funding for the pilots but questions about longer-term funding remain.

And though it has been approved for use by the European Medicines Agency — which described its safety as “similar to that of other vaccines” — reported side effects such as an apparently higher rate of meningitis, and convulsive seizures in a small proportion of recipients, could act as a deterrent amid the rapid rise of vaccine hesitancy.

Despite the hurdles and limitations, experts described the pilots as a landmark moment that cements the role of vaccines in global infection control.

Dr. Pedro Alonso, director of the WHO Global Malaria Programme, explained why the world’s first malaria vaccine was such a long time coming. “Parasites are really complex organisms, much more so than a virus or a bacteria. And that’s why it has taken 30 years to develop this first vaccine,” he told Voice of America.

But while it is the first malaria vaccine to make it to national pilot programs, there are several others at various stages of development — each one hoping to learn from the pilots and improve on the shortcomings of RTS,S.