In 2000, one of the UN's Millennium Development Goals committed the world to reduce child mortality rates by September 2015. At the time, out of every 1,000 live births, an average of 90 children died before the age of five.
Now the average is just 46. The UN says 17,000 fewer children are dying every day. Unicef called this "one of the most significant achievements in human history".
And one of the biggest success stories is Rwanda. Between 2000 and 2015, it achieved the highest average annual reduction in both the under-five mortality rate and the maternal mortality ratio in the world. The UN estimates that 590,000 children have been saved.
So how did Rwanda do it? And could other nations follow its example? Four experts spoke to the BBC World Service Inquiry programme.
Dr Fidele Ngabo: Take health care into the community
Dr Fidele Ngabo is head of the division for maternity, child and community health in Rwanda.
"After the genocide, the government's priority was security. We then started to develop the programme of reduction of maternal mortality, child mortality, and began to see progress in 2005.
"We had four top killers - malaria, diarrhoea, pneumonia, and malnutrition - diseases which can be treated by simple intervention. So we selected 45,000 community health workers at each village so when the children are sick, instead of spending one or two hours going to a health facility, the community health workers can give the treatment in less than 10 minutes.
"They are elected by the community. The only criteria we give is they can read and write. We give them basic training like how to screen for malaria, how to take temperatures, how to check respiration. For complicated treatment, they are obliged to transfer patients to the health facility."
The workers are not given a regular salary, but are paid for what they achieve:
"If they have 100 children in the community who need to be vaccinated during the month, we pay them according to the number who are vaccinated. If 80% of children are vaccinated, we give them 80% of the money.
"The most important thing is to bring service closer to the community, that's what people can really learn from our country."
Randy Wilson: Mobile technology can save lives
Randy Wilson's company Management Sciences for Health helped the Rwandan government to put in place a mobile phone-based text messaging system called RapidSMS.
"We helped to introduce RapidSMS within the districts, training 45,000 community health workers, many of whom who had never touched a cell phone in their life.
"The objectives of the system are to provide a rapid communication between community health workers and other levels of the health system. It has a very simple message format. We've prepared and printed plasticised cards which have codes for different child health and maternal health events.
"First the child or the mother would be registered in the system, and that would basically be a short message with a code for registration and then one or more codes for any health problems. If any immediate feedback is required, there are a number of SMS messages that can be relayed back to the community health worker.
"If there's even the slightest evidence of the signs listed in the list of codes that the community health workers can identify, it encourages the community health worker not only to refer but also to accompany the mother to a facility where they get proper care. That certainly avoids a delay which is often a cause of death.
"The system [also] helps to ensure that people are in the community, face-to-face with the patient and working. So it keeps people honest in terms of their daily routine."
Claire Wagner: Dr Agnes Binagwaho has played a crucial role
Public health researcher Claire Wagner first worked for Rwanda's Minister for Health Dr Agnes Binagwaho five years ago.
"Dr Binagwaho is one of the most important public health figures in the world today, if not the most important, and has led some of the most remarkable declines in premature mortality that the world has ever seen.
"She was born in Rwanda, though spent her training years in Belgium and France.
"When she moved back to Rwanda in 1996, there was absolutely no treatment available for kids with HIV. She had just come from France where there were treatment options [but] in Rwanda she was only able to prescribe rest and nutrition. Her vision that Rwanda's children would be able to receive anti-retroviral therapy combined with advocacy from the First Lady (Jeannette Kagame) led to an incredible HIV response that has continued until today.
"The minister will always say that 'if you give me a penny to help my grandmother, I'll make sure that it also works for my granddaughter'. She ensures that all of the investments that are coming in should go to build a strong health system.
"Fifteen years ago when Rwanda actually launched its community-based health insurance programme, it gave the first health insurance to Rwanda's poorest million inhabitants, which is a signal to the world that this is going to be a new health sector that is focused on local ownership of the country's future. Ninety-eight percent of Rwandans are now covered.
"The government of Rwanda and the Ministry of Health has a set vision. It's no secret that NGOs and other foreign investors who are part of the health sector in Rwanda work in line with the vision of the health sector, or they don't work there at all."
Jose Manuel Roche: Countries must also tackle inequality
Jose Manuel Roche is head of research at Save the Children UK, and recently wrote a report comparing how 87 countries have tackled child mortality.
"Rwanda is one of the six countries in Africa that met its commitment on health spending. They implemented some interventions that are really effective, for example increasing vaccines and having more health workers and a compulsory health insurance scheme.
"They have [also] improved female empowerment, education, nutrition, water and sanitation. Those also affect children's chance of survival.
"It goes beyond a fast improvement. They have been able to reduce it fast, but they have also ensured that those that are more deprived, the most marginalised groups are able to catch up with those that are better off in the country. So it's a story of fast but also more equal progress.
"One of the problems of the Millennium Development Goals (MDGs) is that they were only looking at the national average. They didn't look at whether those who were worse off were also making progress. The MDGs were blind to inequalities.
"Many of the countries have achieved fast progress through reaching those that are low-hanging fruit, those that are much easier to reach. So there's a group of countries where the inequalities are actually widening.
"Bolivia, Cameroon, Central African Republic, Chad, Iraq, Niger, Pakistan, the Philippines and Togo: those were all countries where some achievements were made in terms of reducing child mortality, but the gaps between those that are worse off and better off are widening.
"Although they made very important progress in Vietnam, some very poor ethnic groups were being left behind by having different language, because the information on health is not provided in all the languages.
"Countries that reduce inequalities in child mortality were also achieving faster progress in the long term."
But there have been sharp criticisms of Rwanda's human rights record, for jailing opposition leaders and obstructing independent civil society. Has Rwanda been able to achieve this success because of the authoritarian nature of its government?
"Of course you need to have a government that can deliver. But progress in the short term when you don't also have the space for political change, for democracy, would imply challenges in the future.
"There are of course other dimensions of well-being that matter, and some of those are to do with empowerment, participation, the possibility to speak for yourself, and to be the driver of your own destiny. And in that sense, Rwanda of course [still] has things they need to solve."