"Despite the falling efficacy over time, there is still a clear benefit from RTS,S/AS01," Greenwood said.

"An average 1,363 cases of clinical malaria were prevented over four years of follow-up for every 1,000 children vaccinated, and 1,774 cases in those who also received a booster shot. Over three years of follow-up, an average 558 cases were averted for every 1,000 infants vaccinated, and 983 cases in those also given a booster dose."

"Given that there were an estimated 198 million malaria cases in 2013, this level of efficacy potentially translates into millions of cases of malaria in children being prevented," Greenwood said.

The RTS,S/AS01 vaccine was developed for use in sub-Saharan Africa where malaria still kills around 1300 children every day.

The phase-3 randomised trial enrolled 15,459 young infants (aged six to 12 weeks at first vaccination) and children (five to 17 months at first vaccination) from 11 sites across seven sub-Saharan African countries (Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and United Republic of Tanzania) with varying levels of malaria transmission.

In 2014, initial phase-3 results at 18 months showed vaccine efficacy of about 46 percent against clinical malaria in children and around 27 percent among young infants.

Eoin Treacy's view

Malaria represents a heavy burden in terms of the drag it imposes on the growth potential for afflicted countries. Any measure to lessen the impact can only be considered positive. As such the invention of a malaria vaccine is an enabling development for African countries reaching their productive capacity. 

The Bill and Melinda Gates Foundation have been particularly active in this field and the RTS,S/AS01 vaccine has come about as a result of their efforts in conjunction with GlaxoSmithKline.  

The share has returned to test the region of the 200-day MA and the upper side of its underlying range. A sustained move below 1500p would be required to question medium-term scope for additional higher to lateral ranging.