A vaccine aid group said on Friday it was seeking $4 billion to protect as many as 130 million of the world's poorest children against diarrhea and pneumonia.

Children in developed countries are routinely immunized against the bacteria causing those deadly diseases -- namely Hib, pneumococcus and rotavirus -- but in much of Africa, Asia and Latin America, young people remain dangerously exposed.

The Geneva-based GAVI Alliance, backed by the Bill & Melinda Gates Foundation, said a big immunization push could be another giant leap toward reducing child mortality in our lifetime in part thanks to a global decline in vaccine costs.

Immunization is one of the most cost-effective ways to save lives, Julian Lob-Levyt, head of the GAVI Alliance, said in a statement released ahead of World Pneumonia Day. And improved health is a fundamental driver for long-term development.

GAVI -- or the Global Alliance for Vaccines and Immunization -- is supported by the World Health Organization, the World Bank, UNICEF, vaccine makers and research centres, as well as the Microsoft founder's philanthropic arm.

It raises money by leveraging long-term aid commitments from countries through capital markets, with regular offerings of vaccine bonds organized by the International Finance Facility for Immunization (IFFIm).

The United Nations and various aid groups have sought to replicate the GAVI approach with proposed sanitation bonds to pay for water infrastructure and latrines in poor countries.

GAVI spokesman Jeffrey Rowland told journalists that the $4 billion would finance pneumococcal and rotavirus vaccinations in addition to the large-scale campaigns already under way to fight a range of preventable diseases including hepatitis B, diphtheria, tetanus, whooping cough and Hib.

The scale of GAVI's purchasing and distribution has allowed it to secure much lower prices for vaccines, which are then made available to developing countries at a fraction of that cost.

For instance, pneumococcal vaccine prices have dropped by more than 90 percent, from about $90 to $7, said Rowland, who explained that GAVI's developing country partners would pay between 10 cents and 15 cents for the jabs.

Pneumonia is responsible for one in four child deaths -- more than HIV/AIDS, malaria and measles combined. Its two main bacterial causes are Hib and pneumococcus, which children in developed countries are routinely immunized against.

GAVI estimates that introducing pneumococcal and rotavirus vaccines in between 42 and 44 countries could save up to 11 million child lives by 2030.