About ten percent of those who are infected for COVID-19 get infected from people with no symptoms. Researchers from the University of Texas at Austin studying the novel coronavirus that causes COVID-19 made this finding. The team was also able to identify how quickly the virus spread. Their paper will be published in the journal Emerging Infectious Diseases.
Serial Interval of Four Days
The research team, which included scientists from the United States, France, China and Hong Kong, looked at what is called the serial interval of the virus. This is the time it takes for symptoms to appear in two people from the virus: the person who infects another, and the infected second person.
The serial interval for people in China infected with the coronavirus is four days, according to the researchers. This is one of the first studies to give a definite serial interval time for COVID-19.
How fast an epidemic spreads depends on the serial interval and another variable called the reproduction number. The reproduction number is how many people each case of COVID-19 infects. The short 4-day serial interval of COVID-19 means this epidemic spreads fast and could be difficult 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,” said Lauren Ancel Meyers, one of the researchers from UT Austin in their 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,” she said.
One in Ten is Pre-Symptomatic Transmission
Meyers’ team looked at 450 infection case reports from 93 cities in China. They were able to ascertain that more than 1 in 10 infections were from people who had the virus but showed no symptoms. This type of viral transmission is known as pre-symptomatic transmission (also referred to as asymptomatic transmission).
The team said that all the quarantine measures, travel bans, and closures are warranted because of pre-symptomatic transmission.
“Our findings are corroborated by instances of silent transmission and rising case counts in hundreds of cities worldwide.”
“This tells us that COVID-19 outbreaks can be elusive and require extreme measures,” Meyers said.
With how fast and silent COVID-19 can spread, this pandemic has brought big challenges to the world. How this all play out remains to be seen.