In an article published in the journal Emerging Infectious Diseases, a team of scientists from the United States, France, China and Hong Kong managed to calculate what is called the serial interval of the virus.
In order to measure the serial interval, scientists observe the time required for the appearance of symptoms in two people infected with the virus, that is, in a person who infects another and in that second infected person. Researchers found that the average serial interval of the new coronavirus in China was approximately four days, reports Jutarnji list.
This is also one of the first studies to assess the rate of asymptomatic transmission. Namely, the speed of the epidemic depends on two things, that is, on how many people each individual infects with the coronavirus and how long it takes for the infection to spread among people. The first quantity is called the reproduction number (R), and the second is the serial interval. The short serial interval of Covid-19 means that outbreaks will grow quickly and be difficult to stop, the researchers said.
"Ebola, with a serial interval of several weeks, is much easier to prevent than influenza, with a serial interval of only a few days," says Lauren Ancel Meyers, a professor of integrative biology at the University of Austin. He adds that the data show that the coronavirus can spread like the flu, that is, that they have a similar serial interval.
Meyers and her team analyzed more than 450 case reports from 93 Chinese cities and found strong evidence that people without symptoms are transmitting the virus, known as pre-symptomatic transmission. According to the paper, more than one in 10 infections were transmitted from people who did not yet have symptoms. Until this research, scientists did not have "tangible" evidence of asymptomatic transmission of the virus.
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