As the coronavirus pandemic swept the world, scientists became increasingly aware of its strange and dangerous behavior.
While coughing was observed in many patients, the sense of taste and smell disappeared and the temperature rose, in others infected the disease did not manifest itself and they did not even realize that they became carriers of COVID-19, writes BBC News, informs enovosty.com/news.
Researchers say it is necessary to understand how many people get sick without symptoms, and whether such “silent distributors” really feed the pandemic.
When flocks gathered in one of the churches in Singapore on January 19, no one could even imagine that this would have global consequences for the spread of coronavirus.
On Sunday, one of the sermons was traditionally conducted in Mandarin Chinese. Among the audience was a middle-aged couple who arrived in the morning from China.
The guests looked completely healthy, and no one would have thought that they were carriers of infection. At that time, it was believed that a constant cough should be a mandatory symptom of coronavirus, and that it is in this way that the infection is most likely transmitted.
And there are no symptoms – there is no infection, they thought then.
The Chinese soon left the church, but very quickly things took a sad turn, and no one could understand what was happening. Already on January 22, the woman fell ill, and two days later her husband fell ill. This did not cause any particular surprise, because both of them flew from Wuhan, where the epicenter of the coronavirus arose.
However, next week, for no apparent reason, three Singaporeans fell ill with COVID-19 – these were the first, most mysterious cases of infection in the country at that time. It was the investigation of the causes of their illness that later led to the discovery of new and very alarming details of how the coronavirus so successfully found new victims.
“We were very puzzled,” says Dr. Vernon Lee, head of the Singapore Department of Health’s Infectious Diseases Department. “People who didn’t know each other managed to rebound without showing any symptoms of the disease.”
These new cases did not fit into the picture of what was known about COVID-19 at that time.
Therefore, Dr. Lee, together with his colleagues and with the help of the police and special “virus hunters”, began an investigation, creating a detailed map of when and where the infected people were. This process is called “contact discovery,” and is now being applied in the UK and many countries. The process is to identify all those involved in the outbreak of the disease in order to eradicate it. And Singapore has become known for the speed and efficiency of this process.
In just a few days, the participants in the investigation were able to interview 191 parishioners of the same church and find out that 142 of them were on duty on Sunday. It quickly became clear that two sick Singaporeans were present at the service along with a Chinese couple.
“They could talk to each other, shake hands during that service,” says Dr. Lee.
This was an important step in the investigation, which could explain how the infection was transmitted, but one key factor was missing. There was no answer to the important question: how could the Chinese transmit the virus, if at that time they did not have any symptoms of the disease.
There was also a much more complicated mystery. The fact of the infection of yet another Singaporean woman, who, however, was not present at that church service, was confirmed. True, she was in the church that day, only a little later. So how could she pick up the virus?
In search of evidence, the investigators decided to study the recordings of surveillance cameras made that Sunday. And then they discovered something completely unexpected. It turned out that the infected woman, who had visited the church after the Chinese had left, was sitting in the same chair that one of the spouses occupied several hours earlier.
As it turned out, although the husband and wife did not show any symptoms of the disease and felt normal, they were still carriers of the virus. Perhaps the virus passed onto the chairs from their fingers or stood out when breathing, it is not known for sure, but the consequences were the most serious.
When Dr. Lee collated all the evidence, he had only one explanation: the virus was transmitted by people who were infected, but did not realize it. This discovery was significant for the whole world, because so far all the recommendations on COVID-19 have been reduced to recognizing symptoms in oneself and others.
A new study showed that one or two days before the onset of obvious signs of the disease, people can already be infectious, perhaps this is even the most infectious period.
This is potentially a very important factor, because as soon as you realize that you can be sick, everyone who was in close contact with you can be warned about the need for self-isolation.
That is, such isolation can be provided during the key phase of infection, when the symptoms have not yet manifested. However, the question of how the disease can spread without coughing, in which viruses enter the air, remains open.
One version is that infection can occur when talking and just breathing. If the virus is reproduced in the upper respiratory tract, it is possible that part of the virus is excreted with each exhalation. And everyone who is nearby, especially indoors, can easily become infected.
Another potential transmission opportunity is through touch. The virus may fall into your hands when you touch an infected person or a doorknob — or while sitting in a church. Whatever the route of infection, the virus exploits the fact that people lose their vigilance when they are unaware of the possibility of catching the infection.
Even more asymptomatic people found themselves on the Diamond Princess cruise ship, which the epidemic found off the coast of Japan. The liner was dubbed the “Petri dish”, that is, a real breeding ground for infection, because on board there were about 700 cases of infection.
At the same time, three quarters of the identified infected showed no symptoms.
And in one of the nursing homes in Washington, more than half of the inhabitants tested positive for coronavirus, but showed no signs of illness.
Different studies give completely different data on the number of asymptomatic infections, ranging from 5% to 80%. This was the conclusion of the professor at Oxford University, Karl Henegan, who, together with his colleagues, studied the results of 21 research projects on this topic.
An alarming signal to the authorities was the results of one study conducted in China, according to which the number of asymptomatic infections is actually even higher than the number of patients with symptoms.
“Being“ silent peddlers ”, asymptomatic carriers require increased attention in the interest of containing and controlling the disease,” the scientists write.
“Asymptomatic cases may be the very“ dark matter ”of the current epidemic,” says Professor Hall. We are talking about the notorious invisible substance, of which, presumably, for the most part the matter of our universe consists, but which has not yet been discovered.
Professor Hall fears that asymptomatic cases, despite all the authorities’ efforts to protect public health, continue to fuel the current epidemic.
“If there are people who do not suspect that they are sick, and at the same time use public transport and medical facilities, this will inevitably lead to an increase in infections,” the scientist says. “Any actions in relation to people who came to medical institutions with symptoms of the disease will only be a half-hearted solution to the problem.”
According to a group of scientists from California, asymptomatic carriers are the “Achilles heel” of our fight against the coronavirus pandemic.
They are convinced that the only way to stop the spread of the disease is to identify all infected people by testing, regardless of whether they have symptoms of the disease.
And they propose to pay special attention to health and social welfare workers who are in contact with a risk group.