Covid study by the University of Mainz: How the virus spreads

Where is the risk of infection particularly high, is testing also a question of age and what role do children play? A large Covid study by the University of Medicine Mainz examined this – with some surprising results.

Katja Heyles enters personal data into a special app from the University of Mainz on her smartphone. Heyles takes part in the “Gutenberg Health Study”. “I’ve been involved for eleven years and have been involved in a wide variety of research series,” she says. This way, you get an excellent in-depth analysis of your body again and again. “At the same time, I can also advance science.”

Heyles also took part in the current Covid study. For this purpose, she was examined several times in the clinic and has been answering questions about her everyday life regarding Corona via the app since October.

The “Gutenberg Health Study” is scientifically a gold mine thanks to participants like Heyles. The database has been around since 2007. With a total of 15,000 test subjects, it is one of the largest of its kind in the world. The volunteers represent a representative cross section of the population. The study is the basis of constantly changing research projects – from intraocular pressure to obesity.

At the current Investigation into Covid-19a total of 10,250 people take part. The head of clinical epidemiology, Philipp Wild, co-led the study. “Thanks to the broad database, we have a very good basis for analysis – also with a view to the pandemic,” he says. Wild and his team are now presenting the first results of their corona examinations. Further results will follow.

Unknowing virus carriers

One of the main findings: more than 42 percent of all those infected with corona do not know that they are carrying the virus, the doctor explains. So there is a risk that they unconsciously pass on the pathogen and the pandemic can spread further. “People with a higher social status are more likely to know about their infection. They also carry out tests more frequently,” said Wild.

Younger people can be tested more often

The Mainz scientists also found that older people are unknowingly infected much more often than younger people. The answer to this result can be seen in the test behavior of the population. There are big differences here. Graded according to age group, the study shows that younger people were tested significantly more often than older people aged 65 and over. “Younger people take part more in social life and therefore use the tests more often,” Wild interprets the figures. In addition, the elderly were the first to be vaccinated and people with full vaccination protection were less likely to be tested.

Children are not drivers of infection

Wild and his team also come to the conclusion that children are not the drivers of the infection. To this end, around 2,200 people from families with children were examined. “It is speculated again and again that children spread the virus heavily. They cannot keep the distance or do not wash their hands as often. However, overall we do not see a higher risk of becoming infected in children.” In the families themselves, children would not pass the virus on more than average.

In addition, children are less prone to infecting themselves. “There are cases in which the parents had a corona infection but their children did not. Mothers and fathers also hugged or kissed their children,” explains Wild. Nevertheless, there is often no infection here. A presumed reason: Children have a better immune defense compared to adults.

The more people, the higher the risk

The decisive factor for the spread of the virus is rather the number of people who live together in a household. The higher this is, the greater the risk of infection, according to the epidemiologist. According to the study, people with a low socio-economic status are particularly affected here – i.e. less education, less income or cramped living conditions. “However, it is a prejudice that this group would not adhere to the AHA rules so much. According to our data, the opposite is actually the case.” You would wash your hands more often and keep the distance. Rather, the generally poor living conditions increased the possibility of infection.

However, the willingness to test and vaccinate is also lower in this population group. Politicians can counteract this with special information campaigns, advises Wild. “Socially weaker people also bear the main financial burdens of the crisis. Of course, the cramped living conditions cannot be changed quickly.” However, grants for the purchase of masks or corona self-tests are conceivable, after all, the already tight household budget of this group fell again during the pandemic.

Distance and Mask – and Tests

The Mainz study also examined the effectiveness of individual measures in the fight against corona. Accordingly, the minimum distance is particularly important. A protective mask also leads to better protection. The home office also counteracts the spread. However, the other two measures are more effective.

In addition, epidemiologist Wild vehemently advocates further systematic testing – also of vaccinated people. “At the moment, people are less and less able to be tested. This should be counteracted. This can significantly improve control of the infection process.”

More and more people are being vaccinated. The protection against a serious course of the disease amounts to at least 90 percent, depending on the age group. Nevertheless, there remains a residual risk that increases in the general population. “With a close-knit test system, we would keep an eye on Delta. We should also prepare for the next Corona variant. In view of the many unknowing infections, testing is like an early warning system.”

Open schools – with air filters and hygiene rules

What does all of this mean for daycare centers and schools? Is face-to-face classes possible after the summer holidays, although many children are likely to remain unvaccinated? There is currently no approved vaccine for children under the age of twelve, and the STIKO only recommends it to a limited extent for older children.

Study director Wild has a clear opinion on this: Since children are not drivers of infections, daycare centers and schools should remain open in the fall in the current situation. But there must be clear concepts – with air filters, hygiene rules and test strategies. “That should also be implemented right at the start of school. The earlier we act, the earlier and more effectively we will get to the next wave – and it will definitely come.”