Most people infected with mers have caught it from someone who did not have any symptoms. On it informs the British edition Daily Mail, citing a study by a team of Irish scientists.
Scientists from Ireland have examined 17 of the international research to estimate how many cases of transmission of the disease occurs in the so-called “predentary” period. They found that from 33% to 80% of patients contracted the virus from people who did not even know that they were infected.
On average, it takes six days before a man begins to show clear signs Covid-19, which include, for example, increased body temperature and constant dry cough.
In addition, experts are urgently trying to figure out exactly how the virus spreads among asymptomatic people in order to be able to control this process.
Lead author of the scientific work of Miriam Casey from University College Dublin and her colleagues collected data from 17 international studies. One of them was held in Wuhan, a Chinese city where it originated “killer virus”. Were also used data from Hong Kong, Singapore and Italy.
Special attention was paid to the incubation period – time interval between exposure to virus and onset of the first symptoms. Its median when the coronavirus, according to the calculations of scientists, was 5.8 days. It is believed that people are not contagious and can not transmit the virus to others during this period.
In addition, the Dublin team said that most cases of transmission of infection occurs between 3 days before onset of symptoms and 2 after that. And the peak of contagiousness, on average, occurs in 0.67 day before the onset of symptoms.
Scientists used this information and a mathematical equation to estimate the number of infections, which is the result of presentando distribution.
In one study, which was attended by 137 people from the Chinese municipality of Tianjin, it is estimated that more than 80% of the people were infected resulting in presentimage spread of the disease.
According to the study conducted in Wuhan with the participation of 12 people, the virus from patients without signs of coronavirus picked up a little more than 33% of patients. But in Northern Italy with 240 participants was 36.3%.
Analyzing all available data, Miriam Casey and her colleagues estimated that 56.1% of cases, transmission occurs from people before they develop symptoms of the disease.
According to her, also expect high variability presentano distribution Covid-19, because the way it is transmitted and how it affects people may vary in different countries.
In addition, scientists said that such transmission can lead to the uncontrolled spread of the virus and contribute to the further development of the pandemic.
It is worth noting that the research team from Dublin have been criticised by other scientists in the review process, published on the website MedRxiv.
“These findings underline the urgent need for extremely fast and efficient detection of cases, contact tracing and quarantine measures, if the measures of social distance have to ease,” wrote on the website, another group of scientists.
Previously, contact tracing was proposed as a way of combating the spread of the pandemic with simultaneous removal of restrictive measures. It involves identification of all who were in the vicinity of coronavirus patients before they were diagnosed.
Theoretically, these people should be isolated, even if they have no signs of disease. That is why they will not be able to transmit the virus to others during presentimage period.