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

If most transmission occurs before disease is apparent (as happens in HIV), reactive control measures (where public health workers wait for cases to appear in order take measures like contact tracing and quarantine) will be ineffective. Conversely, successful disease control (as happened with SARS-1) is facilitated by low transmission by asymptomat

This image had first been conjured by an MIT professor of meteorology, Edward Lorenz, on December 29, 1972, at the 139th meeting of the American Association for the Advancement of Science. The details were not exactly the same; Lorenz had used the image of a butterfly flapping its wings in Brazil setting off a tornado in Texas.82 But the image was

The virus had announced itself with extremely unfortunate timing, right at the start of the annual chunyun (春运) migration in China that was taking place in the run-up to the Lunar New Year festival, on January 25, 2020. During this period, over three billion trips are typically made, a mass movement that puts the annual Thanksgiving travel in the U

Another crucial feature that made SARS-1 easier to control than SARS-2 is that it was generally not transmissible before a patient was symptomatic. That was why a large percentage of SARS-1 infections showed up in medical professionals—they were exposed to SARS-1 patients who were already quite sick. It was precisely when these patients went to the

The initial “imported” cases set off local outbreaks via cascades of what epidemiologists term community transmission.

But later investigation revealed that there had been other cases of atypical pneumonia earlier in December, above the threshold for notifying the central Chinese Center for Disease Control in Beijing, that had gone unreported. Precious time to contain the outbreak was lost. In fact, a later analysis documented that there were 104 cases and 15 death

However, because of the scarcity of tests, the CDC initially recommended that people with respiratory complaints be tested only if they had a travel history to China or an exposure to a known COVID-19 case, guidance that would persist until February 27. As a result, in the six weeks after the identification of Patient Zero, only fifty-nine other ca

For SARS-1, the R0 was computed to be in the range of 2.2 to 3.6, and it’s probably between 2.6 and 3.0.

This variation in R0 across individuals in a population can be quantified, and this quantity can have subtle but important effects on the course of an epidemic. The higher this variation (or dispersion), the more likely an epidemic will feature both super-spreading events and dead-end transmission chains. That is, an epidemic involving a population