The World Health Organisation (WHO) believes this has contributed to the difficulty in controlling the spread of COVID-19.
However, the virus can be contained through strict social distancing measures and effective testing.
Maria van Kerhove, a WHO epidemiologist, explained how the virus is more prevalent in the body at the point a person develops symptoms.
Van Kerhove told a live session on social media: “It appears from very limited information we have right now that people have more virus in their body at or around the time that they develop symptoms, so very early on.”
Both the US and Germany have launched preliminary studies and it is thought people with mild symptoms can be infectious for up to nine days.
Van Kerhove added: “it can be a lot longer for people who are more severely ill.”
This comes after the WHO epidemiologist suggested that coronavirus victims with no symptoms were extremely rare.
At the live session, van Kerhove was questioned on the matter explained although some may not develop symptoms, they can still infect others.
She said: “Some estimates of around 40 percent of transmission may be due to asymptomatic (cases), but those are from models.
So I didn’t include that in my answer yesterday but wanted to make sure that I made that clear. Van Kerhove said.”
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WHO’s top emergencies expert, Dr. Mike Ryan, explained the coronavirus travel in the upper respiratory tract, which allows the virus to transmit droplets.
Unlike other viruses such as SARS or MERS, which house within the lower tract.
Ryan said: “Now as we look at COVID-19, we have an infectious pathogen that is present in the upper airway for which the viral loads are peaking at the time you are just beginning to get sick.”
“That means you could be in the restaurant feeling perfectly well and start to get a fever, you are feeling ok, you didn’t think to stay home, but that’s the moment at which your viral load could be actually quite high,” he said.
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He continued: “And it’s because the disease can spread at that moment that the disease is so contagious, that’s why it spread around the world in such an uncontained way, is because it’s hard to stop this virus.”
But some countries have shown that transmission can be brought down to “an acceptable level or even to no level”, as New Zealand had recently demonstrated, he said.
The latest confirmed global death toll for the coronavirus stands at 409, 650 deaths.
As of 8pm, 9th June more than 7 million people have tested positive for the virus.
Currently the United States has recorded the most cases of the virus, with Brazil the largest country affected.
More than 100,00 deaths have occurred in the United States.