For millions of people, malaria creates a grim drumbeat of death, heartbreak, and loss: Every seven seconds, someone gets a case of malaria, and every two minutes, the disease claims another victim under the age of five. That’s why public health experts rejoiced yesterday when the World Health Organization made a landmark decision to endorse the first vaccine against malaria.

Years of clinical trials have shown that this vaccine—known as RTS,S/AS01, or Mosquirix—is safe and helps protect against the disease, especially in concert with other malaria-fighting tools. With a 12-month efficacy of 56 percent, RTS,S lacks the eye-popping effectiveness of other modern vaccines. However, the vaccine’s target—the parasite Plasmodium falciparum—is orders of magnitude more complex than a virus.

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