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U-Bahn in Berlin (symbol picture)
Photo: Reuhl / Fotostand / imago images
According to a new study, the risk of infection for commuters in buses and trains is no higher than in private transport.
This was announced by the Association of German Transport Companies (VDV), which commissioned the study.
A subsidiary of the Berlin Charité carried out the investigation, which was financially supported by eleven federal states.
However, the analysis has some weaknesses.
The Charité Research Organization selected 681 commuters between the ages of 16 and 65 for the study.
They tested negative for the coronavirus before the start of the study and had no antibodies against the pathogen in their blood.
Both of these indicate that they have not yet been infected with the corona virus.
In addition, none of the participants was vaccinated against Covid-19 during the study period.
Individual travelers were infected with comparable frequency
The test persons were randomly divided into two groups of approximately the same size: One drove to work, school or training by car or bicycle for four weeks, the other by local public transport in the area of the Rhein-Main-Verkehrsverbund (RMV) .
The public transport commuters spent 15 to 30 minutes on the bus and train per route.
After the test phase, all study participants were examined for acute or survived infection with the coronavirus using PCR and antibody tests.
Another examination was carried out five weeks later in the event that someone had been infected during the examination period, but tests would only turn out positive later because of the incubation period.
In a diary, the test subjects also noted with whom they had contact, whether they developed symptoms and whether they had complied with the applicable regulations.
At the time of the investigation, it was mandatory to wear an FFP2 mask in local traffic.
The result of the study: Those who used public transport were not infected more often. However, the risk comparison is based on very low numbers. In the individual transport group, 14 people tested positive for the coronavirus in the period under review, and twelve among the public transport commuters, the VDV told SPIEGEL when asked. The statistics are therefore fraught with great uncertainties.
With such a small number of cases, two infections more or less are very likely a coincidental result.
In other words: The data cannot reliably say how high the risk of infection actually is in the car compared to private transport - especially since transport is not the only place where infections can occur.
It is also conceivable that study subjects used the FFP masks more consistently and correctly than is generally the case.
What previous studies say
Basically, the risk of infection increases wherever people come together closely, spend long periods of time in poorly ventilated rooms and talk. That is why public transport has been a possible source of infection since the beginning of the pandemic. A higher frequency, distance rules, hygiene measures and the wearing of medical masks should ensure more safety.
However, it is difficult to assess how high the risk of infection really is. The Robert Koch Institute (RKI) had hardly registered any outbreaks in public transport in a study last autumn. According to this, only 13 outbreaks in buses were known by August 2020, in which an average of five people were infected. Up until then, there was not a single proof of infection for the railway, but the RKI explicitly points out that infections may simply not have been recorded there.
Most outbreaks were reported in the home environment, with more than 3,900 outbreaks recorded for this category alone. These are much easier to discover because if someone is proven to be infected, the direct contact persons are often tested. Tracking is much more difficult on public transport because it is not clear who was traveling with whom and for how long. The Corona warning app documents risk encounters, but not when and with whom exactly they took place.
That is why research teams use so-called cohort studies like the current study. It is not the first of its kind. Last autumn, Deutsche Bahn presented a study according to which train attendants in long-distance traffic were not infected more often than colleagues without direct contact with travelers. However, it is unclear whether this can be transferred to other public means of transport such as underground trains, suburban trains or buses and may also depend on the individual capacity utilization and technical equipment, such as the ventilation systems.
The transport companies still see their current study as a sign that travel in local public transport is safe even in the corona crisis.
"But I would also like to point out clearly that the results of the study had certain framework conditions that must continue to be guaranteed," said Maike Schaefer, Senator for Mobility of the Free Hanseatic City of Bremen and Chairwoman of the Conference of Transport Ministers.
"Keep your distance, wear a mask, ventilate and, of course, the lower occupancy thanks to home office helps ensure that public transport continues to function reliably."
The federal and state governments also continue to urge people to avoid unnecessary travel, regardless of the means of transport.
