Science’s COVID-19 reporting is supported by the Pulitzer Center.
A Chinese company will turn to Brazil for help. The World Health Organization (WHO) is adopting a strategy forged in a war zone during an Ebola outbreak. And the Trump administration plans to lean on existing U.S. infrastructure for tackling HIV and flu. These are some of the disparate strategies about to be employed in the next and most important stage of the COVID-19 vaccine race: the large-scale, placebo-controlled human trials needed to prove which of the more than 135 candidates are safe and effective.
Two such efficacy trials plan to start next month, even as the United States and global initiatives struggle to answer major questions, from what it means for a COVID-19 vaccine to work to how to find enough people exposed to the virus so a candidate can be put to a real-world test. Populations that have high levels of viral transmission are a moving target—Wuhan, China; Seattle; or Milan might once have been a good place to test the mettle of a vaccine, but no longer. And quickly enrolling tens of thousands of properly informed people who meet a trial’s entry criteria is a “big lift,” says Susan Buchbinder, an epidemiologist at the San Francisco Department of Public Health who runs vaccine trials.