One morning in Baltimore last October, a 26-year-old named Alexander Laurenson strode into a small white room to have his arm preyed upon by mosquitoes. As requested, he had not showered the night before to make his skin more attractive to the pests, drawn as they are to body odor. The mosquitoes, for their part, had been infected with malaria, a disease that kills over 600,000 people every year.
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Mr. Laurenson was part of a study at the University of Maryland School of Medicine to test a new monoclonal antibody designed to prevent malaria transmission. Specifically, he had agreed to take part in a human challenge trial, a research method in which volunteers are knowingly infected with a pathogen.
In preparation, the room had been secured to ensure against the mosquitoes’ escape, with a bug zapper installed on the wall and a few electrified paddles added as extra precautions. One by one, over 20 volunteers shuffled inside to serve as prey.
Trials like this one have long underpinned the development of vaccines for deadly scourges like typhoid and cholera. Today, they are typically undertaken only with diseases that already have fast-acting drugs to ensure recovery. But because of the perceived risk involved, and their significant cost, challenge trials remain rare and, in some cases, controversial.
“A lot of people say, ‘Doesn’t this violate the Hippocratic oath?’ or ‘How can a doctor do this?’” said Seema K. Shah, a bioethicist at Lurie Children’s Hospital and professor at Northwestern University in Illinois who studies challenge trials.