When asked why the corona virus has so far affected Eastern Germany far less than the West, the President of the Robert Koch Institute provided two very likely explanations this week – and a hypothesis.
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It is certain that skiers brought the virus from Austria to Bavaria and Baden-Württemberg, in particular, at the beginning of the epidemic, where large events in part fueled the spread. It is also very likely that the higher population density in some regions of western Germany has contributed to the virus initially being able to spread uncontrollably.
In addition, RKI boss Lothar Wieler mentioned a third point. A working hypothesis, he said, that has not yet been proven and is unclear whether it can be proven at all. It is the BCG vaccination, a live vaccination against tuberculosis, in which those affected are injected with weakened pathogens and which was mandatory in the GDR.
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According to the theory, it could not only prepare the immune system for a tuberculosis infection, but also strengthen it in the fight against other pathogens such as the corona virus. Vaccination has not been recommended in Germany since 1998 because the risk of tuberculosis infection is too low and this does not justify the side effects.
Why BCG vaccination may protect against corona
It can hardly be clarified whether vaccinations from the GDR era actually contribute to the slow spread of the coronavirus in many parts of eastern Germany. However, researchers are already working on studies to show whether vaccinations now administered can reduce the risk of coronavirus infection or weaken the course of Covid-19.
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For decades, scientists have been pursuing the idea that live vaccinations such as BCG vaccination not only arm the body against the vaccinated pathogen, but also cause an unspecific reaction of the immune system, which protects against a wide variety of other pathogens. The WHO classified this hypothesis in 2014 as at least plausible. It could be explained, among other things, by epigenetics – chemical changes in genes that affect how often they are read.
In a recent article in “The Lancet”, a team of researchers, including the head of the World Health Organization (WHO) Tedros Ghebreyesus, described the scientific evidence that BCG vaccination is used to fight the coronavirus. At the same time, they warn against widespread use before an effect is proven.
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Studies have shown, among other things, that BCG vaccination can reduce the risk of respiratory diseases, the authors write. In addition, they report, among other things, on an investigation in Guinea-Bissau, a country where child mortality and diseases such as HIV, diarrhea and pneumonia keep life expectancy below 60 years old.
BCG vaccination was able to reduce mortality in underweight newborns by 38 percent. In particular, deaths from pneumonia and sepsis decreased.
How researchers want to test the hypotheses
From a scientific point of view, however, these studies are only the pillars of a theory that still has to be checked for the coronavirus. In April, a study was launched in the Netherlands with 1,000 doctors and nurses who were given either the BCG vaccine or a placebo.
The researchers want to monitor how often the employees in the two groups are infected with the coronavirus. Sufficient volunteers reported within a few days. One of the two study directors is one of the authors of the current “Lancet” contribution.
In addition, the University Clinic of Utrecht started a study with 1,600 people aged 60 and over to determine whether BCG vaccination can reduce the risk of infection or a severe course of the disease in older people. Similar studies are ongoing in Australia and England.
And also in Germany, scientists are working on an investigation with 1000 volunteers from the clinic and emergency services. However, the decades-old BCG vaccine is not to be tested, but a genetically modified version of the Max Planck Institute for Infection Biology.
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Why vaccinating everyone is not a good idea yet
As long as it is unclear whether and how well BCG vaccination protects against the coronavirus, the World Health Organization (WHO) recommends using it only in controlled studies. In the “Lancet”, the researchers give four reasons for this:
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For one thing, there are already supply bottlenecks with the vaccine. This could endanger children who live in areas with a high risk of tuberculosis and who still urgently need vaccination to this day.
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It is not yet possible to say whether the vaccination will do anything for the coronavirus. There are descriptions from areas like East Germany, in which there is a high BCG vaccination rate and few Covid 19 sufferers. However, these were not sufficient as evidence, the researchers write. They consider it unlikely that vaccinations given decades ago in childhood still have a relevant effect.
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If the BCG vaccine does not help, it could give the wrong feeling of security.
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Controlled studies are needed to analyze possible negative consequences of vaccination for Covid 19 disease. This is important in order to rule out that vaccination in a minority may work exactly the opposite way and make the disease more severe.
It is clear that the BCG vaccination can lower the risk of infection, if at all, but does not have the same effect as a targeted vaccination. If their effects are confirmed, however, they can be an instrument to bridge the time until a targeted vaccine is available in future pandemics, the researchers write in the “Lancet”.
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