Super-spreader: this brings so-called “backward” tracking news

Because we now know more about the virus, scientists say it is easier to determine the location of an infection.

There is still much that is not known about the coronavirus. But what is now quite clear: it does not spread well and evenly from one to another. No, the situation is very volatile.

Marcel Salathé

Professor of Epidemiology

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Marcel Salathé is an epidemiologist at ETH Lausanne (EPFL). He is a professor and directs the EPFL Digital Epidemiology Laboratory. During the crown crisis, he is a member of the federal task force, the “Swiss National COVID-19 Task Force.”

“Many people infect no one or only one, but certain people infect many,” says Marcel Salathé, epidemiologist at ETH Lausanne. It is an annoying property on the one hand, it makes the virus more unpredictable. This over-scattering, as experts call it, can also be viewed positively and can be tried to use.

Reference to the same place of infection

Actually, it is demonstrated in the fact that the virus spreads mainly in so-called super spread events or clusters. The idea now would be for contact trackers to quickly try to find these super spread events. “It’s not even about who he was, but where he was from,” says Salathé.

If people suddenly appear on the system who were all in the same event and all could have been infected during this period, this is a possible indication that the event is a so-called cluster. “And there may be many people who have also been infected, but who do not know it because they are asymptomatic.” That is a big problem with this disease.

An example: contact trackers note that firstly there are more cases and secondly that those affected were all at a wedding six days ago. The suspicion: that could be the source of all these infections. “If you have identified such a group with this backtracking, then of course that is not the end,” says Salathé. “So you still have to follow up with all the people who were at this event. »

Precisely because the coronavirus behaves so unstably and so many people are so frequently infected in individual places by individual people and none elsewhere, if you focus more on these groups, you are much more likely to seek infected people where it pays . says the ETH researcher.

There is a new recommendation in progress

This has been done for a long time to some extent. Every contact tracker naturally thinks about where the source of infection might be when they have an infected person in front of them. But the so-called backtracking, or backtracking, wants to give more weight and systematize the procedure.

With checklists, for example, where groups arise with particular frequency: in discos, choirs, bowling alleys and weddings. The Federal Office of Public Health (BAG) is currently working on a new recommendation that will contain suggestions on what this could mean in concrete terms for the contact tracker.