Reports published in journals Lancet it also shows that Covid-19 patients asymptomatic can clear the virus more quickly from their body and may be contagious for a shorter time.
In the first systematic review of its kind, researchers analyzed data from 98 previous studies on the transmission of coronavirus infections.
Reported Huffington Post, Friday (20/11/2020), researchers looked at three key factors in the study:
- Viral load, the number of viruses detected in the body through various stages of infection.
- Viral RNA shedding, the length of time a person releases viral genetic material.
- Isolate live viuses, where live viruses are isolated and tested to see if the virus can successfully reproduce in the laboratory.
The researchers compared their findings about Covid-19 with two other types of coronavirus, to better understand why Covid-19 is spreading so fast.
They found that viral load of SARS-CoV-2 (the virus that causes Covid-19) peaked in the upper respiratory tract early in the course of the disease, between the onset of symptoms and the fifth day.
This finding is important, because viruses in the upper respiratory tract are considered to be the main source of transmission.
In comparison, viral loads for the other two strains of the coronavirus (SARS-CoV and MERS-CoV) peaked at 10-14 days and 7-10 days, respectively. This means that the time for the spread of the virus is longer for symptom recognition and quarantine.
“Our findings are in line with contact tracing studies that show that most viral transmission events occur very early, and particularly within the first five days after the onset of symptoms, which suggests the importance of self-isolation as soon as symptoms begin,” said study lead author Muge Cevik said.