Corona: At this point in time there is the highest risk of infection

Because the corona virus is spreading so quickly, the population must observe contact restrictions, sufficient distance and hygiene measures. Current research results reveal when sick people are most contagious.

Study: Half of all sick people become infected before the onset of symptoms

An illness as a result of the corona virus can only rarely be ruled out, because the incubation period of Sars-CoV-2 infections can last up to two weeks. Scientists have looked more closely at when people are contagious and whether the virus is more commonly transmitted before or during the symptom phase. The result: There is a very specific point in time when infected people are said to be particularly contagious.

According to a Chinese study by the University of Hong Kong (HKU) , 44 percent of infections occur before the onset of symptoms. That would mean that about half of all those infected were infected by someone who was not visibly ill at the time.

At this point in time, people infected with the corona virus are most contagious

The virologist Christian Drosten also dealt with this study and explains: “…Then the frequency peak for infectivity is even half a day before the onset of symptoms, on average”. This means that Sars-CoV-2 sufferers are most contagious on average about half a day before the symptoms start! On average, the virus can be transmitted around two and a half days before the first symptoms appear.

The findings are now supported by official sites. It is considered scientifically proven that the SARS-CoV-2 coronavirus is greatest in the period around the onset of symptoms and that a significant proportion of transmissions occur before the symptoms appear . The exact period during which the infected person is contagious is not certain. However, it is clear that the risk of infection decreases as the disease progresses.

Compliance with the distance and hygiene measures is therefore still essential – even if you cannot (yet) identify any symptoms.

Study: risk of infection indoors

Martin Kriegel and Anne Hartmann from the Hermann Rietschel Institute at the TU Berlin calculated how high the risk of infection via aerosols in closed rooms is – and compared different situations with each other. The results have not yet been checked by peers, so possible errors cannot be ruled out. The so-called R-value plays an important role in the calculations by Kriegel and Hartmann. It indicates the number of people infected when there is an infected person in an indoor space at the same time. If R is less than or equal to 1, then the number of new infections decreases.

There is therefore a high risk of infection in open-plan offices and classrooms . A low risk is in theatres, museums or operas that have low occupancy rates, in hairdressers and on public transportto be expected – provided masks are worn and social distancing is maintained. According to the researchers, medical mouth and nose protection can reduce aerosol emissions and the amount inhaled by around 50 percent. “What is clear from the study is that it is above all the situations in which we like to be that are unfavorable,” summarizes Kriegel in an interview with Spiegel Online. “Situations where a lot of people come together in a small space: you can’t ventilate sufficiently, it will always be an unfavorable situation.”

Crystal Waston MD

Crystal Waston has a degree in Cross Media Production and Publishing. At vital.de she gives everyday tips and deals with topics related to women's health, sport, and nutrition.

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