Government officials said the IMF-backed debt repayment should free up future budgetary resources for social spending, and would brace Gabon for a gradual decline in its oil revenues.
Despite a slow start, UN officials said the campaign had reached the vast majority of Gabonese children, particularly in rural areas. Some voiced optimism that central Africa could make great inroads against disease if the political will was there.
"We should see a huge reduction soon in the number of children dying from malaria in Gabon," said Andrea Gay, UN Foundation director of child health, adding that more effort would be needed to eliminate diseases such as measles.
"That takes political leadership ... The countries here that have the highest income like Gabon and Equatorial Guinea ought to be doing more," she said.
Demonstrating the importance of political leadership, she noted that a backlash against polio immunisation by traditional Muslim leaders in northern Nigeria in 2003 suspended vaccinations for more than a year and allowed the disease to spread to 10 countries across the Sahel.
CORRUPTION DRAINS RESOURCES
The discovery of oil in Gabon in the late 1960s, during the first decade of independence from France, brought the country billions of dollars in revenue, but it still has one of the most unequal income distributions in the world.
In Libreville, a flood of migrants from the countryside and neighbouring countries live in the ramshackle slums a stone's throw from the city's glitzy oceanfront hotels and offices.
It is a familiar story in much of central Africa.
Equatorial Guinea, with a population of just 500,000, has earned billions of dollars from oil in the past decade but remains in the bottom third of the UN development index.
President Teodoro Obiang's government says it has increased health spending, but IMF officials note the budget for the presidency exceeds all expenditure on healthcare and education. The former Spanish colony completely ran out of vaccines for several months last year, aid workers say.
In conflict-torn Chad corruption drained resources from a recent programme, meaning only a fraction of the planned vaccination teams were deployed.
"In Chad, we were throwing our money down the drain," said one foreign health worker, who asked not to be identified.
President Idriss Deby's government in Chad, ranked as the most corrupt country in the world in 2005 by Berlin-based Transparency International, has created a special ministry to fight graft in the landlocked oil-producing state.
For proof of the role politics can play, some point to the late Thomas Sankara, Africa's "Che Guevara". His four-year government in impoverished Burkina Faso aimed for "a clinic in every village" and practically eliminated polio, meningitis and hepatitis in the 1980s, earning the praise of the WHO.
In Lybe, a village near Gabon's border with mainland Equatorial Guinea, Marie Eyeang says she must travel 25 km (16 miles) to reach a clinic if her baby daughter falls ill.
"I know if a mosquito bites her she can fall sick," she said, cradling her child as she shows off her new mosquito net hanging over the bed. "So this is to avoid sickness."
