Vanity Fair
David Ewing Duncan
May 11, 2020
De Kai, a research scholar at Berkeley's International Computer Science Institute and professor at the Hong Kong University of Science and Technology, is about to release a study he led with an international team of scientists, showing that everyone should be wearing a mask, as they do in many countries in East Asia, to protect against COVID-19. Among the study's findings: If 80% of a closed population wore a mask, infection rates would drop to roughly one twelfth the number experienced in a similar population in which no one wears a mask. The team arrived at their conclusions by building a computer forecasting model they called masksim simulator. Among other things, the simulation took into account differences in effectiveness between different kinds of masks. "What's most important about wearing masks right now ... is that it works, along with social distancing, to flatten the curve of infections as we wait for treatments and vaccines to be developed -- while also allowing people to go out and some businesses to reopen," says masksim collaborator Guy-Philippe Goldstein, an economist, cybersecurity expert, and lecturer at the Ecole de Guerre Economique in Paris. Jeremy Howard, a researcher at UCSF and founding researcher at, who was among a group of scientists assessing the study, said of the work, "It's almost overkill how careful they were with this modeling."