A decade ago, it wasn't unusual to see a Vietnamese family of five cheerfully braving the frenzied traffic of Hanoi on a single motorcycle—with nobody wearing a helmet. No longer. A stringent law passed in 2007 has made helmets compulsory—and has proven that such laws, which require political will more than money, can have a huge impact on public health. Research suggests that the law's passage saved more than 1500 lives the first year and reduced serious head injuries by almost 2500.
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Researchers at the Center for Global Development (CGD) plan to include the Vietnam law in the next edition of Millions Saved, a book on proven successes in global health—but strictly speaking, the evidence doesn't meet CGD's standards. The center prefers to see a randomized study or at least a “quasi-experimental” study design (see main story). That didn't happen in Vietnam. CGD decided to include the case anyway because it's difficult to see what else—besides the law—could have caused the drop. CGD's Miriam Temin hopes Vietnam's success will inspire other countries.