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.
“We also need to raise public awareness about the various symptoms associated with the disease, including mild symptoms that may occur earlier during infection than more prominent symptoms such as cough or fever.”
Most common symptoms:
- Dry cough
Less common symptoms:
- Aches and pains
- Sore throat
- Loss of taste or smell
- Rash on the skin, or discoloration of the fingers or toes
- Difficulty breathing or shortness of breath
- Chest pain or pressure
- Loss of speech or movement
Although viral load It seems to be largely the same among people with and without symptoms, this study shows that people without symptoms can clear the virus from their bodies more quickly.
“Several studies have found that individuals with asymptomatic infection clear the virus more quickly, suggesting that those without symptoms may be as contagious as those with symptoms early in the infection, but can be contagious for a shorter time,” said Cevik.
Cevik added that more research on the spread of the infectious virus in asymptomatic people would be needed before changes to policy on quarantine duration could be considered.
The authors also note that many of the study participants were people who had been hospitalized for Covid-19, so they may have received treatment that affected the course of their infection.
“Therefore, our findings may not apply to people with milder infections, although these results suggest those with milder cases cleared the virus more quickly from their bodies,” said Antonia Ho, senior clinical lecturer and infectious disease consultant at Glasgow Center for. Virus Research.
“More research is needed on viral shedding in this context.”