In Switzerland, the number of Sars-CoV-2 infected is slowly increasing. Many people wonder whether they have already infected themselves unnoticed. It is possible, but is currently unlikely.
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Who is already infected? The risk is much higher in Italy than in Switzerland.
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A dripping nose and a bit of a cough or sore throat plague almost everyone this time of year. But in times of the coronavirus epidemic, people quickly wonder whether they have already contracted the virus – perhaps from their friend, who was in Milan three weeks ago and then had a slight cold. She didn’t go to the doctor to get tested. Why too? Fever and a dry cough have so far been considered the main symptoms of Covid 19 disease.
But that could prove to be deceptive. Because the majority of those infected do not get really sick, but are still highly contagious. At least a small study from Germany suggests this, which was published on Monday in a preliminary version on a preprint website. The doctors around Clemens Wendtner, chief physician at the Munich Clinic Schwabing, describe the first nine Sars CoV-2 infected people who examined them.
Fourteen people infected
The victims were infected in Bavaria at the end of January after a Chinese woman visited a company for a meeting. A total of fourteen employees and relatives subsequently became infected with the virus. Most of them showed hardly any symptoms, just a slight runny nose, headache or a little cough, one of them even stayed perfectly healthy. But all nine people examined in the clinic already had high levels of virus in the throat on the day the first symptoms started – including the man who never got sick on the first day of the exam. The measured amount of virus was on average more than a hundred times higher than in flu patients and more than a thousand times higher than in people suffering from Sars in 2003.
The researchers also showed that the isolated viruses were active. In the laboratory, they quickly penetrated the cells offered to them and began to reproduce there. This suggests that even slightly ill people are highly contagious – and there are obviously many of them.
Twenty-three other Sars-CoV-2 infected patients examined by Wendtner mostly showed only mild symptoms, similar to a cold. “Normally, these people would probably have gone on to work with a bit of a cold and cough. We only examined them because all contact persons are tested, »says Wendtner.
As a result, many infected people are only slightly affected – just as doctors and epidemiologists suspected. On the one hand, that’s good news: most people don’t have to worry about their health. But it also complicates things, because it makes it difficult to distinguish the mild cases of a Sars-CoV-2 infection from a harmless cold. Even people with mild cold symptoms have to think carefully about whether they can still get in touch with older people and other vulnerable groups.
The study also confirms the assumption that children infected with Sars-CoV-2 (who mostly show only mild symptoms) are good transmitters of the virus. It is often argued that the virus may not reproduce well in the child’s body, making children less contagious. So far, however, there is no credible evidence that children are really less contagious than adults.
A normal cold
Nevertheless, those who are currently suffering from a cold can most likely attribute their symptoms to a normal flu-like infection. Because measured against the total population, there are so far very few Sars-CoV-2 infected in Germany and Switzerland. In this respect, the likelihood of being infected is small. However, this will change as soon as the number of infected people increases significantly.
The Munich doctors were particularly concerned with the question of when the healthy people isolated in hospital are no longer contagious and can be discharged. “In the beginning, the instruction was that we should only remove the isolation if we can no longer find any virus material from them,” says Wendtner. However, with the highly sensitive measurement methods, doctors still found genetic material from the viruses in the samples two to three weeks after the first symptoms.
Then, however, the researchers were able to show that the pathogens ceased to be active from the ninth day and the patients were therefore no longer contagious. In order to relieve the hospitals and the mental health of those affected, Wendtner therefore advises that an earlier discharge to a quarantine at home be considered. As a guideline, he considers the tenth day to be useful if the patient’s saliva contains less than 100,000 virus copies per milliliter by then. The more people treated in hospitals, the more important such information is.
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