Most cases of corona virus are caused by people who do not show symptoms of covid 19.
This is stated in the updated guidelines issued by the US Centers for Disease Control and Prevention (CDC).
According to the CDC, this is one of the main reasons for the importance of using face masks.
The CDC said most cases of code 19 are caused by asymptomatic patients.
"According to the CDC and other estimates, in more than 50% of cases, the virus is transmitted from person to person who does not show symptoms," the statement said.
The statement said that this means that at least 50 per cent of new cases are perpetrated by people who do not even know they are passing them on to others.
According to the CDC, 24% of people who transmit the virus to other people never show symptoms, while 35% show it a few days later, while 41% infect others after experiencing symptoms.
The US agency said that a patient is most contagious five days after the onset of the disease, considering that 59 per cent of cases are caused by people who have not yet shown symptoms.
The rate could range from 51 to 70 percent, the statement said.
The study was published in the medical journal Proceedings of the National Academy of Sciences in July this year.
Previously, medical institutions did not provide statistics on the rate of transmission of the virus from asymptomatic patients.
The US agency said that the particles released from the mouth or nose of an infected person during breathing, talking, coughing, sneezing or singing are the main means of making someone sick.
The statement said that large amounts of such particles are emitted while talking or singing loudly.
The CDC said research reports show that 40 to 45 percent of cases are caused by asymptomatic patients, while people with symptoms can transmit the virus to others before they do.
According to the agency, the rate of cases is highest when a patient has the highest viral load and because the symptoms do not appear, such people do not even know that they are sick.
The CDC added that cloth face masks can protect people from these viral particles.
The CDC recently said in its guidelines that the use of face masks can protect people from swallowing large and small viral particles.
