The Coronavirus without symptoms contagious?

Currently, it is still unclear how many people have been infected unnoticed with the Coronavirus SARS-CoV-2. For this purpose, the proportion of the disease plays an important role in the runs without or with very mild symptoms. The first studies to supply evidence for this share.

From the people who were tested positive for SARS-CoV-2, shows that around 80 percent of all COVID-19-diseases, mild or medium severe. These cases can be treated in a domestic quarantine. It is unclear, however, how many people have been infected unknowingly and unnoticed.

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Why is the number so important?

The number of laboratory-confirmed Coronavirus cases provides only a limited explanatory power. If you want to know how fast the pandemic can be defeated, it is necessary to know the number of unreported cases. Only in this way can be used to determine how widespread the Virus really is and what are the immunities in the population against SARS-CoV-2 prevalence. As a rule of thumb: If 70 percent of a population have immunity, the epidemic defeated.

Corona: How can you determine the number of unreported cases?

The dark figure can be determined by not only people with symptoms or people who were Infected in contact, to be tested, but random samples are carried out in the population – and as many as possible. This is due to the limited test capacity so far, but only with difficulty. Some studies carried out in small isolated populations.

The village with the first of the Corona the case of death in Italy

Researchers from the Imperial College London carried out, for example, a study in a small Italian village, where almost the entire population were tested to determine the number of unreported cases. The results of the study can be found on the Preprint Server “medRxiv”.

In the northeast Italian municipality of Vo live 3.304 persons. 21. February 2020 died a resident of the municipality of pneumonia due to SARS-CoV-2 infection. This was the first COVID-19-death case was found in Italy. In response, the regional authorities imposed the blocking of the entire municipality for 14 days.

Almost a whole community has been tested

A research team at the Imperial College under the direction of Neil Ferguson, of London, whose Team groups is one of the world’s leading epidemiologists-tested at the beginning and at the end of the contact lock of a majority of the population in the small cordoned-off area to get more precise information about the number of unreported cases, the herd immunity and the spread of the corona virus.

Corona infections without symptoms is possible

The researchers tested at the beginning of the Isolation 85.9 per cent of the population in Vo and at the end of the insulation, once again, 71.5 percent of all persons living in the household. The Team found out through the surface of the deck at the end of testing, was that the beginning of the Isolation 2.6 percent of the community already infected. At the end of the contact lock, only 1.2 percent of the inhabitants were infected residents. Through interviews with the infect people, it turned out that 43.2 percent of all diseases were asymptomatic, without complaints.

Corona without symptoms contagious

By tracking the chain of Infection, the research team was able to show that asymptomatic Infected goods for a majority of new infections are responsible, occurred during the Isolation in the house. The study is among the first research that the incidence of asymptomatic SARS-CoV-2-light infections, and gives new insights into the transmission dynamics and the effectiveness of measures such as Isolation and contact restrictions.

Drosten is impressed by the study

Even if the study is not yet published in a professional journal, have been impressed with the results of the virologist Professor Dr. Christian Drosten. The 43.2% of asymptomatic cases were identified the Coronavirus-according to experts, due to a precise data collection. “I think this is a number that you now can work in the future,” said Drosten Podcast in his NDR.

The Heinsberg-study in Gangelt

A similar research project conducted by the state government in North Rhine-Westphalia under the direction of renowned virologist Professor Dr. Hendrik Streeck in Gangelt, Kreis Heinsberg. Since the population is in Gangelt, but much larger, has been tested only on a random basis.

The research project “Covid-19 Case-Cluster-Study” came to the preliminary conclusion that at the time of the study (at the beginning of April 2020), with around two percent of the population in Gangelt acute COVID-19-disease suffered. About 14 percent of the samples in the population anti-body showed against SARS-Cov-2, suggesting that immunity. Overall, about 15 percent of the inhabitants were infected residents in Gangelt with the novel Coronavirus.

Corona: How high is mortality rate?

From this result, even for the Region Heinsberg deduce that the Corona-mortality rate is significantly lower than previously assumed. Consequently, 0.37 percent of the Infected died. This Rate is well below the 1.98% lethality provided by the Johns Hopkins University. The Heinsberg-study shows clearly that mortality can realistically be shown, if the number of asymptomatic cases is also taken into account.

Virologist Streeck emphasises, in this context, but that is to be expected that the compliance with stringent hygiene measures, and the measures taken, the insulation measures, the mortality rate is small. In the case of extraordinary outbreak events (“super spreading events”) such as carnival, parties, discos, concerts, football games, Oktoberfest, and the like, it could lead to uncontrolled propagation. This could lead to a repeal of the health care system, and the death rates to skyrocket, similar to that in Spain, Italy and the USA.

Anti body tests are intended to reveal the dark figure

The Problem with the currently available studies, however, is that it is an isolated and relatively small communities. What applies, for example, in Vo or Gangelt, must not necessarily be on large cities such as Berlin and Munich transferable. The Robert Koch Institute (RKI) wants to uncover the dark figure now at the Federal level. For this purpose, several nationwide anti-body studies are planned.

Corona: How is determined the herd immunity?

In the part of the already initiated studies nationwide, for example, all 14 days of 5,000 blood samples for SARS-CoV-2 antibodies tested. In addition, the RKI plans 2000 participants examine the end of most affected places in Germany in regular intervals. Here, clinical symptoms, pre-existing conditions to behavior, health, life circumstances as well as mental health be taken into account. First results from these investigations are expected in the beginning of may, 2020.

Furthermore, the RKI will perform from mid-may to 15,000 samples at 150 locations in Germany, in order to measure the distribution of antibodies in the population. These results could be of great importance to the course and the Severity of the pandemic, a more accurate estimate. First results are expected in the course of June 2020. (vb)