AUSTIN, Texas — Americans, and people all over the world, are waking up today faced with a concerning reality. The novel coronavirus (Covid-19) isn’t “just the flu,” isn’t going away anytime soon, and is very much going to impact every single person’s life. As we all brace for weeks of time spent at home, it’s more important than ever to stay calm and stick to the facts. To that end, here are some important new findings just released by a team of international researchers working out of the University of Texas at Austin.
They believe they’ve discovered how quickly the virus can spread, a potentially invaluable piece of information in the containment effort. In a transmission chain, it appears that the time between cases is less than a week. Moreover, over 10% of new infections are being spread by carriers with no outward signs of illness.
Scientists from the United States, China, France, and Hong Kong collaborated on this research, and have calculated Covid-19’s serial interval.
Serial interval is the amount of time it takes for symptoms to show themselves in two people; the original carrier who infected someone else, and the second infected person. In China, the average serial interval was roughly four days. If you had any trouble following all of that, this essentially means that if an infected person with no developed symptoms passes on the virus to someone else on Monday, it’s fair to predict that both will be showing some emergence of symptoms by Friday.
Traditionally, the speed in which an epidemic spreads is determined by two factors: how many others are infected by each case, and the amount of time it takes for cases to spread. Unfortunately, Covid-19’s short serial interval means it is an especially tricky virus and one that will be hard to contain.
“Ebola, with a serial interval of several weeks, is much easier to contain than influenza, with a serial interval of only a few days. Public health responders to Ebola outbreaks have much more time to identify and isolate cases before they infect others,” says Lauren Ancel Meyers, a professor of integrative biology at UT Austin, in a media release. “The data suggest that this coronavirus may spread like the flu. That means we need to move quickly and aggressively to curb the emerging threat.”
The study’s authors analyzed over 450 coronavirus patients from 93 Chinese cities. Along the way, they gathered the most compelling evidence to date that Covid-19 is undeniably being spread by asymptomatic or pre-symptomatic carriers. Researchers estimate that 10% of studied infections were caused by people who had the virus but didn’t feel sick yet.
“This provides evidence that extensive control measures including isolation, quarantine, school closures, travel restrictions and cancellation of mass gatherings may be warranted,” Meyers comments. “Asymptomatic transmission definitely makes containment more difficult.”
The situation is changing rapidly, and each day the narrative changes. So, as more and more data is collected these numbers and estimations may have to be adjusted. However, it’s clear that Covid-19 is a unique and elusive threat.
“Our findings are corroborated by instances of silent transmission and rising case counts in hundreds of cities worldwide,” she concludes. “This tells us that COVID-19 outbreaks can be elusive and require extreme measures.”
The best approach we can all take moving forward is limiting our contact with others and practicing social distancing. The next few weeks will be a challenge, but the virus is containable, as evidenced by the major progress and improvements being made in the virus’ epicenter, China.
The study is published in Emerging Infectious Diseases.