The first five days after the onset of symptoms are the most dangerous for the patients with the coronavirus and those who surround them. This is evidenced by new large studies.

The study indicates that patients had the highest levels of the virus in the early stages of care. In addition, a ‘live’ virus capable of reproduction was detected in them up to nine days after the onset of symptoms. That is why, according to British scientists, early isolation is crucial to stop the spread of the virus. The study was published in the journal ‘Lancet Microbe.’

The infectivity of a sick person depends on many factors, including the number of viable viruses (capable of reproduction) in the body.

Some studies show that people are most contagious just before they have symptoms and during the first week of illness.

The researchers analyzed 79 worldwide studies of the Covid-19, which involved patients with symptoms in hospitals who tested positive for the virus. The researchers were able to identify and replicate a viable virus from samples taken from patients’ throats up to nine days after the onset of the disease. They also found that the number of viral RNA particles (fragments of the genetic material of the virus) in the samples reached a maximum at the time of symptoms or during the first five days. Meanwhile, inactive fragments of viral RNA were found in samples from the nose and throat on average up to 17 days after the onset of symptoms.

The researchers concluded that although such fragments persist, it is unlikely that most people will be contagious nine days after the onset of symptoms, because after that time, scientists have not found any viable virus capable of replication. Dr Muge Chevik of the University of St. Andrews told the BBC that the study found that people were most contagious in the early stages of the disease, which is consistent with other research on contact tracking. “People need support,so they can be isolated as soon as they have symptoms, even the slightest. By the time they get the test results, they may have passed the peak of contagion,” she says.

Contagious before symptoms appear? The study did not look at asymptomatic carriers of the virus, but the authors warned that according to other studies, people could be contagious before getting symptoms, and could transmit the virus without symptoms at all. In Britain, officials insist that people should be isolated immediately for at least 10 days if they have any symptoms of the coronavirus.