This week, at the just-concluded 28th African Union Summit in Addis Ababa, we watched with pride as Heads of State endorsed the Addis Declaration on Immunisation in support of ensuring that all African children, no matter who they are or where they live, can access the vaccines they need to survive and thrive.

Vaccines are, without question, among the most effective and cost-effective public health tools available, saving between two and three million lives every year. Vaccines have led to the eradication of smallpox, a 99.9% reduction in polio cases worldwide and a dramatic reduction of other diseases like measles, diphtheria and tetanus.

Immunisation is also rooted in a commitment to equity and is among the simplest means to advance it.

By ensuring every child, rich or poor, receives the same life-saving vaccines, countries can ensure that the next generation starts out on a more equal playing field in terms of their health.

Beyond the individual, the positive ripple effects of immunization are enormous. When children are vaccinated, families, communities and governments can save or reinvest the time and money that would have been spent caring for sick children.

Vaccinated children are more likely to stay in school and ultimately enrich the economy. It’s no wonder that every dollar spent on childhood vaccinations yields $44 in economic benefits.

This week’s commitment by African leaders to act on this wealth of evidence couldn’t have come at a better time. While many countries in Africa have made tremendous gains in immunisation coverage in the last 15 years contributing to child mortality being halved progress has stagnated, leaving one in five of African children without access to life-saving vaccines.

Concrete actions are needed to achieve the targets of 90% immunisation coverage in every country and 80% coverage in every district by 2020, as outlined in the Global Vaccine Action Plan.

The stakes have truly never been higher for ensuring that every child in Africa has access to life-saving vaccines. The largest generation of young people that the world has ever seen is poised to come of age, and Africa’s youth population is growing faster than that of any other region in the world.

In 2015, 226 million youths aged 15-24 lived in Africa. By 2030, that number is projected to increase by 42%. By 2050, the working age population in sub-Saharan Africa will more than double.

By investing in young people today, starting with vaccines that keep children alive, healthy and in school, African nations have an incredible opportunity to harness the "demographic dividend”, a surge in healthy, educated and skilled working-age adults who can catapult countries into a period of rapid economic growth and stability.

That’s the focus of this year’s AU Summit and why this high-level commitment to immunization matters so much.

The first requirement for accelerating progress on immunisation is already at hand: increased political will. Now, political will must be followed by action, including in the form of increased domestic financing.

In some countries, two major sources of funding could soon decline: funding for polio eradication will decrease as progress is made and cases decline, and countries with stronger economies will receive less international aid in the coming years.

In response, governments must put financial muscle behind their verbal support especially as fewer than 15 African countries currently fund more than half of their national immunisation programmes.

Finally, immunisation efforts must be underpinned by robust health systems that are strong at the primary health care level and deliver services based on need, not ability to pay.

We leave this year’s AU Summit filled with optimism and resolve, ready to tackle the challenges that lie ahead. With commitment at the highest levels, we have never been more confident that Africa can and will make vaccine-preventable diseases a thing of the past.

Putting pen to paper was only the beginning. Now, we must build on the momentum of this historic commitment to create a healthier future for all children in Africa. The writer is the World Health Organization’s Regional Director for Africa.