Natasha Singer is a technology reporter for the Business section of The New York Times, where she covers health technology, education technology and consumer privacy. Her article is republished here with permission as part of our licensing program. We welcome your comments below.
Among all the tools that health agencies have developed over the years to fight epidemics, at least one has remained a constant for more than a century: paper vaccination certificates.
In the 1880s, in response to smallpox . . .