Apollo's Arrow: The Profound and Enduring Impact of Coronavirus on the Way We Live

by Nicholas A. Christakis MD PhD

Testing drugs always requires volunteers willing to assume some risk by taking a new and incompletely understood pharmaceutical agent. Ultimately, there must be some “first in human” or “first human dose” studies, known as phase 1 studies. These studies are then followed by phase 2 studies, which involve slightly larger numbers of subjects and attempt to further explore the safety of the drug and, more important, get an initial sense of its efficacy. If this phase is promising, then phase 3 studies, involving a much larger number of people in a randomized controlled trial, are initiated with an eye to quantifying the actual efficacy of the drug. In such pivotal phase 3 studies, one group of people is randomly assigned to get the active agent and another, the control group, gets either a placebo or whatever constitutes the usual standard of care. During phase 3, scientists also assess the possible emergence of rare toxicities that could not have been observed in the small phase 1 and phase 2 studies. Finally, even after a drug is released, ongoing monitoring is necessary to make sure the pharmaceutical works in a broader, representative sample of people who get it and to check for even rarer toxicities (this is known as phase 4).