With the number of new coronavirus patients in the world approaching the one-million mark, scientists in several countries are still trying to uncover the secret of the rapid spread of this disease, and they seem to have laid their hands on a good cause.
US authorities have said that new data shows that many people have become infected with the virus from contact with people who have not had symptoms of the epidemic known as "COVID 19", indicating that it may be necessary to expand precautions, such as the use of protective masks.
The director of the American Centers for Disease Control and Prevention, Dr. Robert Redfield, warned that about 25 percent of people infected with the Coronavirus may have no symptoms, according to an interview he gave to the National Radio, on Tuesday.
Redfield concluded that this figure helps explain the prevalence of the Coronavirus in the world and throughout the United States in particular, as the country has become a major focus of the epidemic.
This huge number of asymptomatic patients, which is estimated at hundreds of thousands around the world, may complicate efforts to predict the course of the epidemic and the strategies in place to limit its spread.
These new estimates could lead to a review of the instructions announced by the Centers for Disease Control in the United States, adding more people to the wearing of medical masks.
And this US government agency had said that the average person does not need to wear the mask unless he feels symptoms of the disease.
According to the New York Times, the researchers do not know the exact number of people infected with the virus without sensing its symptoms, but since the virus first appeared in December, they have detected many disturbing cases of healthy people who spread the infection unintentionally.
For example, a patient who was symbolized by the letter "Z", a 26-year-old Chinese from Guangdong Province in China, had had contact with a returning traveler from Wuhan in February.
But this twenty-year-old did not show symptoms until 11 days after infection, but on the seventh day, the virus had rapidly multiplied in his nose.
Researchers conclude that people like "Z" are no longer rare, as the symptoms of the Coronavirus have not appeared on 18 percent of those infected on the famous cruise ship "Princess of Diamonds".
The Hong Kong research team believes that between 20 and 40 percent of transmission cases in China have been caused by people who have not had symptoms of the virus.
Given that the anti-virus drugs are in the early development stage, the best solution is to apply a "social spacing" rule to reduce the spread of the virus, because a person may pass the virus to others without knowing.
"If you are in casual contact with an infected person, it will be a chance to catch an infection," says the epidemiologist at the University of Hong Kong, Benjamin Curling.
But he added, "The risk increases in case of constant contact with him, such as face-to-face conversation."