The pharmaceutical company Pfizer has pledged to cut the price of its new vaccine against a deadly disease by 6%, but campaigners say the reduction is nowhere near enough.

Last week Médecins Sans Frontières called for a reduction of the price of the vaccine against pneumococcal disease to $5 (£3.30) per child, claiming the two companies manufacturing it were making large profits.

At a donor conference in Berlin hosted by Angela Merkel to raise funds for the global vaccines alliance Gavi, Pfizer offered to cut the price from $3.30 a dose to $3.10. Each child needs three doses.

The other company making the vaccine, the British drugmaker GlaxoSmithKline, said it would freeze the price for 10 years for middle-income countries that lose Gavi funding because of their increasing wealth.

But MSF said the concessions were not enough. “Pfizer’s tiny price cut for the pneumococcal vaccine is inadequate. We need to see both Pfizer and GlaxoSmithKline take bolder steps to reduce the price of this vaccine in developing countries so that more kids can be protected against pneumonia,” said Kate Elder, vaccines policy adviser for MSF’s access campaign.

“Considering Pfizer has raked in nearly $16bn for this vaccine in just four years, we think the company can do much more than a meagre 6% discount.”

MSF also wants much greater transparency from companies, complaining that they do not reveal the costs of researching, developing and manufacturing vaccines nor the prices they charge in different countries. The Guardian launched a crowdsourcing exercise asking readers around the world to help fill in the gaps by finding out the price of the vaccine where they live.

“Pfizer claims that it is making the pneumococcal vaccine available to the poorest countries at below cost price, but we really don’t know if that’s true,” Elder said. “We need to see both Pfizer and GSK opening up their books – being transparent for a change – on what the real costs of the research, development and production of this vaccine are. The secrecy that shrouds the vaccine industry makes it almost impossible to have an educated discussion on reasonable vaccine prices.”