London : The GAVI global vaccine alliance has offered funding of up to $27.5 million for pilot tests of GlaxoSmithKline's first-generation malaria vaccine, but only if other organizations promise to match that commitment.

Evidence so far on the shot, developed by the British drugmaker with financial backing from the Bill & Melinda Gates Foundation, "suggests a malaria vaccine could have a significant impact in reducing malaria mortality in Africa", but more research is needed, GAVI said.

Speaking to Reuters after a board meeting in Geneva, Seth Berkley, GAVI's chief executive, said the alliance was ready "to play its part" in backing the first phase pilot studies if other funders also came forward. GAVI is working with UNITAID and the Global Fund to Fight AIDS, TB and Malaria on the issue, he said.

He added, however, that GAVI's board had made clear that this "should not be considered as an indication of future GAVI funding" for this vaccine, or for future similar pilot schemes for other vaccines.

Since the vaccine - known as RTS,S or Mosquirix is only partially effective and needs to be given in a four dose schedule outside normal childhood vaccination plans, experts have questioned its potential usefulness and cost effectiveness.

The World Health Organization (WHO) said last year that while Mosquirix is promising, it should be deployed only on a pilot basis before any wide-scale use, given its limited efficacy.

The WHO is now in the process of finalizing the design of the pilots in three African locations. The projects are expected to delay any possible broader roll out of Mosquirix by between three and five years.

"Measuring the vaccine's impact in real life settings is what will ultimately help the health community assess the value of this vaccine in the fight against malaria along with other existing interventions," Berkley said.

Malaria infects around 200 million people a year worldwide and killed an estimated 440,000 in 2015. The vast majority of malaria deaths are among babies in sub-Saharan Africa.

GAVI, which is backed by the Bill & Melinda Gates Foundation, the WHO, the World Bank, UNICEF, donor governments and others, funds bulk-buy vaccination programs for poorer nations that can't afford shots at developed-economy prices.

"Malaria's heavy burden on Africa means it is vital that we understand the impact of this vaccine in communities," Ngozi Okonjo-Iweala, chair of GAVI's board and who is also a former Nigerian finance minister, said in a statement. "We call on others to come forward with sufficient funding to enable the pilots to proceed."