An economist says lower health care costs are just the tip of the iceberg
By Melinda Wenner

David Bloom

David Bloom first became interested in international health in the late 1980s. At that time he was an established labor economist, and the economic aspects of the AIDS epidemic intrigued him. Bloom recalls that his colleagues strongly discouraged him, telling him that "AIDS was a fad" and that "good scientists didn't work on trendy topics." He ignored them.

"Those kinds of comments had the unintended consequence of hastening my professional transition from US labor issues to global health," says Bloom, chair of the population and international health department at Harvard's School of Public Health. "And for the past 10 to 15 years, that's where I've concentrated my attention."

Bloom is perhaps best known for his 2005 study published in World Economics, with fellow Harvard economist David Canning and independent policy consultant Mark Weston. Linking vaccination to economic growth, the study assessed a Global Alliance for Vaccination and Immunization (GAVI) program designed to expand vaccination in 75 low-income countries over the course of 15 years. It compared the program's costs, estimated at $13 billion, to its benefits by translating the estimated increased life expectancy into wages and per capita income. They found that the rate of return to the program - the economic gain generated from the investment - would amount to 12.4% in 2005 and 18% in 2020, suggesting that vaccination is "as important, if not more important, than education," says Bloom.

The second part of the study looked at the effects of immunization on the language, math, and IQs of 1,975 10-year-old Filipino children. After controlling for confounding factors, Bloom and his colleagues found that children who had received six basic vaccines scored significantly higher on the tests than children who had not.

Public health researchers weren't especially surprised by these findings. The idea that good health has secondary benefits is "something that we in health had taken for granted," says Orin Levine, associate professor at Johns Hopkins' Bloomberg School of Public Health.

To macroeconomists, however, the findings came as a bit of a surprise. Macroeconomists had always assumed, says Bloom, that the causal link between health and wealth pointed only in one direction: from wealth to health. While it is "undoubtedly true" that prosperity boosts well-being - people who have more money have access to better nutrition, sanitation and medical care - Bloom's work suggests that the arrow also points in the other direction.

"Macroeconomists really had blinders on with respect to the idea that healthier populations promote faster economic growth," Bloom recalls, but "by and large, the overwhelming conclusion that emerges is that healthier populations grow their economies faster."

Bloom also points out that the first part of his study, which considers only the direct effects of longer life expectancy on income, underestimates the economic benefits of vaccination. It did not incorporate the potential effects of better cognitive development, fewer sick days at school, the fact that people who expect their families to live longer have fewer children and tend to save more, and that healthy countries attract foreign investment, he says.

Even if its findings are understated, Bloom's study has already made an impact on those involved in vaccine promotion. It "has been extremely, extremely helpful in terms of educating policy makers and decision makers of their need for investment in health and in vaccines in particular," says Ciro de Quadros, Director for International Programs at the Sabin Vaccine Institute, a nonprofit organization based in Washington, DC, which promotes global vaccine development and distribution.

Bloom's work has also brought the fields of economics and public health - whose "interests are much more closely aligned than I think anybody realized," says Bloom - together for the first time. "He's built a bridge between two communities that previously weren't really understanding one another," notes Levine.

Bloom plans to next tease out which characteristics of healthy populations promote economic growth and to identify simple ways to boost well-being. He also plans to study the link between vaccination and health more closely - he describes his 2005 study as a "back-of-the-envelope effort" through randomized controlled trials. "It's a field that right now is very much in its heyday," he says. "The pace of advance in the field is really picking up, and it's exciting to be a part of that."