Germany's coronavirus tracking app is becoming increasingly compatible with networks outside Germany. Experts believe that as infection rates continue to rise, the app will grow in importance.
Image: picture-alliance/dpa/R. Weiss
Advertisement
Since the middle of June, it has become a daily ritual for a growing number of Germans: wake up, get up, grab your cellphone, click onto the coronavirus warn app (CWA) and hope to read the following words on a green background: "Low risk. So far no exposure to risk." But things are not as clear and simple as they might seem because thousands of people have also found out – by using the same app, this time with a red light – that they have indeed been exposed to an infected person. And that means that it is time to be tested or go into quarantine.
The good news is: the app is a whole lot faster than just leaving things to the local health departments, where huge and helplessly overloaded teams of employees are using conventional telephone tracking in a painstaking bid to identify and break chains of infection.
Hopes surrounding the app and its potential impact have been boosted in recent days. This is because it has gone international. Since the beginning of this week, the German app has been exchanging warnings with apps from Ireland and Italy.
And it is hoped that Denmark, Latvia, and Spain will follow suit, to later be followed by Austria and the Netherlands, making it increasingly likely that a network of 16 national apps could be in place by the end of the year. Another promising new development is that people who have tested positive can also feed into the system details concerning symptoms and the actual time of infection — important information for anybody who might have been in a contact chain.
A slow beginning
Politicians, epidemiologists and computer gave their backing to the development of a coronavirus tracing app relatively early in the pandemic, hoping it would transmit information on the spread of infections quickly and efficiently. The app was to be both anonymous and optional for users. The result — which took longer to get up and running than most had hoped — was launched in mid June. So far, some nineteen million people have downloaded it in Germany. About sixteen million of them are active users.
Coronavirus rules: How much physical distancing is enough?
Physical distancing is important. But a set distance rule does not do justice to the way viruses actually spread, British researchers say. And the CDC warns: Infections can occur after only a few minutes of exposure.
Image: Reuters/M. Darlington
Keep your distance, please!
These are the coronavirus rules as we know them: Keep a distance of 1.5 to 2 meters (5 to 6 feet) from others, observe good hygiene and wear a mask. But this does not do justice to the complex reality of how aerosols spread, researchers from Oxford and London (UK) and Cambridge MA (US) have written in an analysis published in the British Medical Journal in late August.
Image: picture-alliance/dpa/J. Büttner
This much? Or more?
British Prime Minister Boris Johnson has tried to show schoolchildren how it should be done. But what does his gesture mean exactly? Do his fingertips have to be 1.5 meters away from the fingertips of another person? That would be a reasonable interpretation of the regulations. But two arm lengths alone measure 1.5 meters, so distances of 4.5 meters or more could easily result.
Image: picture-alliance/dpa/Evening Standard/L. Young
Are sheep lengths better?
The Icelandic Association of Sheep Breeders has established its own rules: Two sheep lengths are appropriate to avoid infection. One may wonder if face masks are also supposed to be knitted from real sheep's wool. This young shepherd in Senegal may be trying to find out how long a sheep is by pulling its hind leg. The Icelanders already know — exactly 1 meter.
Image: AFP/J. Wessels
Natural spacers
Of course, this could also work. The standard length of a dog leash corresponds pretty exactly to the current coronavirus rules. Could it be a coincidence that a six-foot leash is usually prescribed for places where leashes are compulsory?
Image: picture-alliance/chromorange
Where does the 2-meter rule come from?
The authors led by Lydia Bourouiba, an expert in fluid dynamics and disease transmission at MIT, writes that the rule is outdated. Two meters was the distance recommended by the German physician C. Flügge in 1897. Visible droplets that he had caught within this distance were still contagious. A 1948 study showed that 90% of streptococci coughed out in droplets flew no further than 1.7 meters.
Image: picture-alliance/dpa/PA/Jordan
Two meters are not enough
The 1948 study was published in the American Medical Journal. It also showed that 10% of streptococci flew much further: up to 2.9 meters. If that were the case, perhaps the people on this lawn on the banks of the Rhine in Dusseldorf would be safe — if every other circle remained free. But wait a minute — we are not dealing with streptococci (bacteria) here, but with viruses.
Image: picture-alliance/dpa/M. Becker
Viruses spread via aerosols
Viruses are much smaller than bacteria, so they can float around for hours and spread better in the air. This is why the researchers recommend that the distance between people should not be the only safety criterion but that other factors should be considered, too: How well a room is ventilated, whether people are wearing masks, and whether they are silent, speaking softly or singing and shouting.
Image: picture-alliance/dpa/Bayerischer Rundfunk
Do not sing or cough
Numerous studies have also shown that coughing can propel veritable parcels of viruses up to 8 meters through the air. Speaking or singing loudly also spread a lot of aerosols and droplets about the room. If, however, people only speak quietly, as in a library, and sit in the fresh air, safe distances can be smaller again.
Image: Getty Images/AFP/A. McBride
How long should I stay in the room?
The duration of a stay in a contaminated room and how many people are in that room are also decisive factors when assessing the risk of infection. The researchers have used those factors to develop a traffic light model. The clear result: In rooms with a high occupancy, you should generally stay only for a short time, make sure they are well aired, wear a mask and speak quietly.
Image: picture-alliance/dpa/S. Hoppe
One minute is enough to get infected
Even very brief contact can be enough to transmit SARS-CoV-2. The US Center for Disease Control (CDC) had to tighten its rules on October 21, after a prison guard caught SARS-CoV-2 from prisoners with whom he had only had contact with for a few minutes at a time. Now, "close contact" is defined as being within 2 metres of an infected person for at least 15 minutes cumulatively within 24 hours.
Image: picture-alliance/empics
No mask needed here
Here, however, the traffic light of the UK-US research team would show green. Outside, people can be safe for long periods of time even without a mask, provided there are few people around, everything is well ventilated and no one talks much. But even so, will the distance between deck chairs being measured here be enough?
Image: M. Melzer
11 images1 | 11
Things certainly did not get off to a great start. The launch date was repeatedly moved back. There were plenty of technical hitches and glitches. And by the time the app was more or less up and running, it was already summer and infection rates were going down. The concern was then that people were using the app to reassure themselves that things were nowhere near as worrying as it had initially seemed.
All in all, Germany's corona app was deemed by many to have made a significant contribution to efforts to tackle the virus. However, speaking at the end of September, a hundred days after the launch of the new technology, Health Minister Jens Spahn of the Christian Democrats (CDU) was cautious in his estimation of the impact of the app: "It is," he said, "only one tool among many in this pandemic."
Right from the beginning, the app was heavily criticized and just a few days ago, the state premier of Bavaria, Markus Söder of the conservative CSU, declared: "Regrettably, the app is a toothless tiger. It provides little in the way of a warning effect."
Söder was referring to what is viewed as a key flaw in the app linked with the guarantee that it would be both voluntary and anonymous. The app uses Bluetooth technology to measure the distance between cellphones and the duration of the close contact. But the system only works when users who have been tested corona positive use the app to register their status. And it appears that to date only sixty percent of them, have actually done so.
Advertisement
Boosting acceptance of the app
With the number of infections rising in Germany, politicians and health experts are sure that they will convince more people to download the app, making it more relevant in the fight against the spread of the virus.
Leading experts like virologist Christian Drosten from the Robert Koch Institute are also calling on the people responsible for tracking and tracing in Germany to take a closer look at the way authorities in Japan are approaching the challenge. What happens there is that people who test positive are immediately asked whether and where they have taken part in any larger-scale events. That may be a useful feature to add, as the assumption now — both in Japan and Germany — is that parties, celebrations and family gatherings are very significant sources of infection clusters.
