Bill Gates is a busy man. Possessing one of the greatest fortunes in world history while simultaneously operating a foundation intent on giving it all away, certainly comes with its share of demands. But as if they weren’t enough, recently, thanks to growing domestic and international concerns, Gates has been lucky enough to add one more item to his general itinerary: defending vaccines.

As co-founder and chair of the Bill & Melinda Gates Foundation, one of the developing world’s greatest sources for funding public health, Gates has been thrust into the unique position of having to defend vaccines against safety concerns, while also defending their profitability – an oft-addressed basis for “Big Pharma” conspiracy theories.

That companies would have the audacity to make money off their highly effective product has long been fodder for vaccine critics, but rising vaccine costs have now earned the consternation of an increasing number of credible organizations, such as Doctors Without Borders. These organizations have issued repeated concerns that the high prices of vaccines are slowing down and complicating immunization efforts across the world.

Gates and his foundation (who, it’s worth noting, recently raised $7.5 billion to spend on vaccinations) not only disagree, but are wary of the outspoken concern. Too much criticism, says Gates, and companies might stop doing ‘research and development on any product that would help poor countries. Then they’re not criticized at all because they don’t have anything that these people are saying they should price at zero.’

These fears are not unfounded (for decades vaccines proved to be so unprofitable that many pharmaceutical companies simply stopped producing them) but they do downplay the potential severity of these cost hikes, not just in the developing world but in the United States as well.

Still, Gates does make one point that cannot be refuted: that immunization ‘is the cheapest thing ever done in health.’ As legitimate as the concern over vaccine costs is, the increases have no chance of falsifying Gates statement about cost-effectiveness any time soon.

According to John Hopkins Bloomberg School of Public Health, “Rolling out childhood immunizations against Hib, pneumococcal and rotavirus diseases in the world’s 73 poorest countries over the next decade would result in an estimated $63 billion in treatment and productivity savings. Additionally “the ability to avert 3.7 million deaths by using pneumococcal, Hib and rotavirus vaccines has an estimated value of $115 billion for those in at-risk countries.”

Amazingly, despite the obvious cost-effectiveness of mass immunization, new studies are discovering that long-term economic benefits have actually been underestimated. ‘If we had calculated the value of savings, averted medical costs, welfare benefits associated with averted deaths or other effects — in addition to productivity gains –vaccination would likely blow the socks off other forms of development aid,’ claims Professor David Canning of the Harvard School of Public Health. ‘The returns on investment in vaccination are at least as large, and possibly much larger, than the returns on basic education.’

Though the rising cost of vaccines may result in crises only foggily foreseen, the positive effects of continuing to purchase them, all over the world, only continue to grow. Millions of lives continue to be saved, fueling the development of the countries in which they are most needed. The Gavi Alliance estimates that by 2020 the money invested in vaccines will “yield an 18% percent rate of return.” The cost-effectiveness of this investment is obvious – so much so that more and more countries are devoting greater portions of their budgets towards immunization. In spite of growing doubts, the numbers only continue to speak for themselves: the effectiveness of vaccines, both cost and otherwise, are only improving the world.