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Contact tracing: How are corona infection chains tracked?

Contact tracing : How are corona infection chains tracked?

The number of corona cases continues to rise - in Bonn too. The public health office is busy with contact tracing. But in many cases the origin of the infection chain is no longer traceable.

"I can only say that our work can only be as good as the information we receive”, declared Susanne Engels, head of the public health office in Bonn last Friday at a press conference in the town hall. The health office is facing more and more work due to the increasing number of infections. Contacts have to be identified and people are sent into quarantine if necessary. "Bonn residents are cooperating well" Engels stressed. Even if sometimes there are language problems, and some people become aggressive or try to negotiate. "There are people who only have to hear the word 'quarantine' and their whole life plan collapses for the next two weeks”.

So how does the tracing work? A young woman from Bonn, who wishes to remain unnamed, works in a Bonn hospital and became infected with the COVID-19 virus. "When the positive test came back, someone from hospital hygiene department called me and asked me what my symptoms were and how long I had had them," she tells the GA. They counted back two days from the day the first symptoms appeared. Who had she been in contact with since then? How long was the contact? Was a mask worn or not? "From this, the man from hospital hygiene department determined who the first degree contacts were," she says, "I had to provide the telephone numbers so that they could be put in quarantine. Second degree contacts, i.e. people she spoke to for a maximum of 15 minutes, were informed by the public health department and should only keep a diary of any symptoms. No quarantine was ordered. "As a precautionary measure, the hospital told my colleagues to work from home first."

She then received the phone number for the public health office. She called and was asked for all her details and her symptoms. A colleague would contact her in the next few days. The following day, the call from the health office came in the morning. "They asked again about my symptoms and private contacts. The contact details that I had given to the hospital hygiene department had already been passed to the public health department.”

The corona app that she had installed on her mobile phone also worked perfectly. Normally, if the result is positive, you get a QR code or TAN, which you have to enter into the app. As she did not receive anything, she called the health office. "The man on the phone asked again about my symptoms, hung up and called me back.” This was to prevent misuse of the app. When calling back, the health office gave her a ten-digit TAN number. "When I entered this number into the app, the positive test appeared with the date. My work colleagues who I share an office with then had a red light on their corona apps too.”

The staff of the health office in Bonn experience daily the difficulty of keeping track of all contacts. "About 40 percent of infection chains cannot be traced back," explains Engels. But this is often not even due to a lack of information. "People simply do not remember everybody they met up with a fortnight ago. A contact diary is helpful”.

Because as soon as there is a positive case, the public health department asks where, how long and with whom you have spent the last 14 days. These people are then called using the contact details provided by the person concerned. "This is sometimes difficult if there are errors in the data provided", says Engels. The first-degree contact persons are then given a corona test. If it is positive, contact tracing continues. If it is negative, only the quarantine applies. The order is first given orally, and followed in writing a few days later, depending on how busy the staff are. In addition, the city offers liaison and assistance - some people have no one to look after them.

A 54-year-old man from Bonn also tells the GA about his experiences with the public health office. He works in the northern part of Baden-Württemberg. "We have an open-plan office and one colleague had corona. He had noticed the first symptoms on 11th October. On Tuesday he tested positive". The colleague reported his positive test to the company and the public health office, with whom he had been in contact over the past few days. Since there was a larger meeting in the company on the Thursday, a good 20 colleagues were affected.

For the man from Bonn, it was initially difficult to find out where to get tested. "On Wednesday morning, I did some research online," he says. He quickly came across the website of the CBT Bonn (Centre for Blood Clotting Diseases and Transfusions). "But the next available date was ten days away." So he called the public health office. The young man on the phone was not really able to help him any further. "He just wanted to know the facts. That didn't help me at first. He then passed me on to a colleague who knew much more. She said that the public health office in Baden-Württemberg would contact me.”

But he still went to see his doctor. On the way there, the health office contacted him and asked him how he had been in contact with his colleague on Thursday. As he had not been in direct contact with him either at the meeting nor over dinner, the lady on the phone did not order him to go into quarantine. By the middle of the week he finally had the result: negative. "It is possible that the colleague wasn’t contagious yet on the Thursday," says the 54-year-old. On Sunday, however, his colleague was "lying flat out”. “And he is actually a sporty young guy. It really knocked him out."

(Original text: Thomas Leurs and Nicolas Ottersbach; Translation: Caroline Kusch)