A newly published study reveals that so-called ‘stealth’ transmission of the novel coronavirus largely fueled the outbreak that impacted China. The study says that many of the COVID-19 cases in China likely didn’t have severe symptoms, meaning infected people may have thought they had a simple cold and went on with their lives. This, in turn, caused the virus to rapidly spread through the Wuhan population.
The new study comes from Columbia University, where researchers say that before the January 23 travel shutdown involving Wuhan, 86-percent of the nation’s infections weren’t yet identified. Despite the undocumented cases being only around half as contagious as the documented cases, the study found that they were responsible for two-thirds of known COVID-19 infections.
The huge outbreak of cases in China was primarily driven by infected people who had either zero or only mild symptoms, the study reports. Study co-author Jeffrey Shaman explained:
Depending on their contagiousness and numbers, undetected cases can expose a far greater portion of the population to virus than would otherwise occur. We find for COVID-19 in China these undetected infected individuals are numerous and contagious. These stealth transmissions will continue to present a major challenge to the containment of this outbreak going forward.
Increases in public awareness about the virus and how to reduce transmission of it, as well as travel restrictions and other control measures, are cited as methods that successfully slowed down the rate of transmission. Whether these efforts will be adequate enough to completely stop the virus’s spread is still unknown, however.