In the category of stunning, heartening, woefully underreported good news: In 2000, an estimated 9.9 million children around the world died before age 5. In 2013, the figure was 6.3 million. That is 3.6 million fewer deaths, even as population increased by about 1 billion.

Shout it from the rooftops. Or, more topically, paste it to the posterior of a celebrity. Put Dianne Feinstein in charge of keeping it a secret.

There are a variety of reasons for increased child survival, including improved prevention of malaria and HIV. But according to a recent report in the Lancet, about half of these gains came from reductions in pneumonia, diarrhea and measles — diseases addressed by vaccination. We are seeing the continuation of what is perhaps the single greatest scientific contribution to human well-being: the artificial preparation of the immune system to ward off bacteria and viruses.

The provision of vaccines is a particularly clear instance of what economists call a global public good. A tetanus shot, for example, is a very good thing for the individual getting it; he or she doesn't end up with lockjaw. But it is not, strictly speaking, a public good. Only the treated person benefits. The broad provision of the pneumococcal vaccine, in contrast, creates herd immunity and reduces antimicrobial resistance. The circulation of pneumonia in children is diminished, helping protect the elderly as well. Once this public good is produced, everyone can enjoy it without reducing anyone else's share.

What is exceptional about this particular public good is how much of it has been generated by a single source. The Internet loves speculation about shadowy, menacing global institutions — the Bilderberg Group, the Trilateral Commission. But there is a little-known global institution based in Geneva — Gavi, the Vaccine Alliance — that supports vaccination for nearly 60 percent of the world's children. It is a global conspiracy of health.

Gavi provides heavy but eventually diminishing subsidies for immunizations in poor countries. It also acts as a sort of purchasing co-op, helping nations get better prices on vaccines. And it amounts to a guaranteed market for vaccines that would not otherwise be profitable to research and produce.

This organization has gathered recent attention during the Ebola crisis. Two Ebola vaccines are currently in testing and may be available (God and the science willing) by the middle of next year. Gavi is raising funds (from governments and development banks) to purchase millions of doses. Perhaps more importantly, it guarantees a market for the development of second-generation Ebola vaccines that will have a longer shelf life and work on a broader variety of strains. In addition, Gavi will help Ebola-affected countries play catch-up on other childhood vaccinations neglected during the crisis.

But the prospect is broader. Gavi has begun an ambitious push to fund its next five-year period, with the target to provide 2.7 billion vaccine doses that will immunize 300 million children. This would prevent 5 million to 6 million deaths. The outcomes of few other development interventions are so precisely measurable. Gavi has a 3 percent overhead rate. The results with a given level of inputs can be specified with incredible accuracy.

And this, in all likelihood, will be the highest level of resources Gavi will ever need. The program requires even the poorest countries to pay a portion of the cost of purchasing vaccines. Participating nations are then given five years to take over the full cost — which they generally do on schedule (barring coup or crisis). This graduation model means that during the next five-year funding period — following the one currently being planned — only 2.1 billion doses will be required. And downward from there.

There is serious debate about the effectiveness of certain types of development assistance. Advocates must be able to account for the lack of economic results, say, from decades of foreign aid in Haiti. But the value of vaccination as a global public good is hard to question. Gavi is rigorous, dramatically effective — and temporary.

The Obama administration and other governments are in the process of determining their commitments to Gavi. America is generally hesitant to make large, multiyear development pledges. This should be a big, bipartisan exception.

Michael Gerson's e-mail address is michaelgerson@washpost.com. His column is distributed by the Washington Post Writers Group.