“If you had a million dollars for health, what would be the best way to spend it?” That question, posed by the Disease Control Priorities Project (DCPP) in August 2008, is poignant, in a way. How could anything be accomplished with only a million dollars? There seems no end to global public health problems. HIV/AIDS, tuberculosis, pneumonia, influenza. Poor sanitation and unsafe drinking water. Malnutrition and parasites. Industrial air pollution and cigarettes and coal-fired power plants and automobile exhaust. Diseases that will not go away (malaria), diseases that threaten to break out and wreak havoc (avian flu), and diseases that we think have gone away but still lurk (polio). Viruses, bacteria, and simple misfortune seem to have unlimited resources; governments, aid organizations, and public health specialists do not. That situation imposes a dispassionate calculus at the heart of DCPP’s question: If not every possible public health intervention can be done, what should be done first?

Johns Hopkins Magazine posed that question to more than 100 researchers from the Bloomberg School of Public Health. As anticipated, we received more suggestions than we could use. So our second step was to cross-reference those suggestions with the second edition of the DCPP study Disease Control Priorities in Developing Countries, known in public health circles by the shorthand DCP2. What emerged was a set of interventions of demonstrated effectiveness that already have been implemented to varying degrees, but given the political will and the resources could be implemented on a wider and deeper scale and so save millions of lives. As Johns Hopkins medical historian Randall Packard points out, nothing on this list gets at the foundation of most human misery—poverty and war—but each intervention has a proven capacity to enhance survival and vastly improve life for many, many people. Think of the list as a good place to start.

Young children are vulnerable to deadly diseases. So vaccinate them.

International health authorities estimate that every year, 10 million to 13 million children die (including stillbirths). That is more than 30,000 per day, every day. The Global Health Council estimates that 1 million of them could be saved by vaccinations against just six diseases: measles, tetanus, pertussis, diphtheria, polio, and tuberculosis. The Disease Control Priorities Project has put forward childhood vaccinations as the single most cost-effective public health intervention in its study.

To make meaningful comparisons among interventions, DCPP used a calculation called disability-adjusted life years, or DALYs. Developed in the 1990s, DALYs combine years lived with illness and disability and years lost to premature death in a single metric that can be used with cost data to create a dollars-per-DALY estimate of cost-effectiveness. The method has limitations (for example, the data used to calculate it have to be reliable, which can be a problem in poor countries), and figures for different regions can vary widely, making something that’s cost-effective in a major South African city much less so in a remote section of Congo. But it’s one of the best available tools, and the basis for this list. In the DCP2 study, the cost of interventions is expressed in DALYs averted; if an intervention costs $10 per DALY averted, that means for every $10 spent you have bought a year of healthy life for someone. In the case of childhood basic immunizations, DCP2 estimates that a year of healthy life could be bought in South Asia for $8, in sub-Saharan Africa for $1–5.

Neal Halsey, Bloomberg School professor of international health, was co-author of the DCP2 chapter on vaccine-preventable diseases. He notes that in 2001 the estimated pertussis deaths averted by vaccines totaled more than 1 million worldwide, for all ages; the comparable figure for measles was 1.2 million deaths averted.

And while you’re keeping an eye on kids, monitor them for prevention or treatment of three killers: pneumonia, diarrhea, and malaria.

Robert Black, Bloomberg professor of international health, chaired a WHO group that determined pneumonia accounts for 19 percent of deaths among children age 5 and younger, killing an estimated 2 million. Diarrhea kills another 17 percent, and in developing countries ranks in the top five among diseases from which children die. DCPP estimates that 1 million kids die from malaria each year. Malaria and pneumonia can be treated with antibiotics, if someone with minimal training is on hand to spot the diseases early and administer treatment. The Global Health Council estimates that the cost per child of antibiotic treatment for pneumonia comes to about 30 cents. Diarrhea can be treated by oral rehydration therapy, using special packets of sugar and salts, at an assumed cost per child (according to DCPP) of 70 cents.

Illustrations by Michael Gibbs