Supported by the Federal Ministry of Health and the Robert Koch Institute
The NET CHECK contact index (CX)
The contact index is a daily calculated value describing the contact behavior for Germany. It is based on statistical determination of contacts from mobile data and corrects a shift in the number of contacts caused by superspreading. In other words, people who have a very large number of contacts. The origin of the contact index can be vividly described.
Background: It is not the total number of contacts that is decisive for the risk of a virus spreading, but the contact index, at least seen statistically for the population. This is based on the so-called friendship paradox: a person with many contacts (purple in the picture) has a greater probability of being in contact with an infected person (red).
Therefore, the pure number of contacts underestimates the incidence of infection and must be corrected with the number of “supercontactors”. The blue curves show computer simulations in a graph of 1 million nodes (with SEIR model). One would naively expect the contact number and R to be linear. However, the true R is much higher. However, the expected linear behavior is obtained with the contact index corrected for the supercontacts.
This effect is extremely high in the contact networks we have determined! People have very different social ties and contacts (heterogeneous contact network).The number of people contacted on a day is very broad, i.e. there are many people who have very many contacts. That is why it is important to use the correction by the contact index and not the number of contacts.
The contact index actually shows a very high correlation with the case-based reproduction number. We were able to show this in a scientific study together with scientists from the Hasso Plattner Institute in Potsdam and the Charité in Berlin. So the case-based R-value can be predicted with high accuracy two to three weeks later.
Fourth wave: Return to the effective contact numbers of the summer is necessary!
The strong increase in effective contact numbers in recent weeks (see contact index) points to a significant increase in effective reproduction numbers followed by a strong increase in incidence in the coming weeks. Model results suggest that a massive outbreak of infection may occur in December if current conditions continue unchanged. More…
Mobilephonedatahave been usedinmanySARSCoV-2analysesduringthecurrentpandemic, butoftenwithlimitedvalueintermsofinfectionrates. Previously usedevaluationsweremostly basedonaggregatedmobility. However, thisispotentiallymisleading because, forexample, themovementofamotoristdoesnotnecessarilyhavetoleadtoaninfection-relevantcontact. DatascientistsandphysiciansfromtheBerlin-basedcompanyNETCHECKGmbH, theHassoPlattnerInstituteinPotsdamandtheCharité–UniversitätsmedizinBerlinarenowpresentingamethodfor usingthedatainanewwayinthejournalPNAS. More. ..
Federal emergency brake failed? Early warning system shows what measures have achieved so far
The federal emergency brake has been in force again in Germany for a week. It is intended to contain the pandemic and reduce the incidence of infection. NET CHECK data experts analyze how effective the measures agreed with it are and how this affects the spread of the virus.
Corona-risik in the supermarket? Almost every third contact happens while shopping!
An analysis by our data specialists now brings supermarkets and discounters into play. More information about the analysis of mobile data by NET CHECK can be found at FOCUS Online: More (publication available only in German)…
Curfews are effective!
Curfew works! NET CHECK analysis of contact events in Bavarian counties shows that the #contact index can be reduced by up to four points through curfews (10 pm-5 am). This means a reduction of the R-value by approx. 5%.
Corona early warning system. Contact index predicts infects behavior until end of February.
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