More and more research highlights that the BCG vaccine against TB could also be effective against Covid-19. Many believe that in countries where vaccination is mandatory, including Hungary, this is why the epidemic did not significantly break loose. Some, however, point out that the current information is not yet sufficient enough to make such a firm statement.
According to some recent studies, there is a clear correlation between the use of the BCG vaccine and COVID-19 infections and the course of the disease. This data suggests that a COVID-19 infection is less likely to lead to the death of patients in countries where BCG vaccination has been compulsory.
But in countries where it has been suspended (e.g. Spain, France), or where compulsory vaccination has never been introduced (e.g. Italy), the mortality rate from the viral infection seems to be much higher.
The BCG vaccine was developed by French physicians and biologists Léon Charles Albert Calmette and Jean-Marie Camille Guérin in the 1900s. It contains a live, weakened strain of Mycobacterium bovis, which is related to the microbe responsible for Tuberculosis. The vaccine is given to children in their first year of life in most countries, including Hungary.
Although most vaccines generally raise immune responses specific to a targeted pathogen, as news site Science points out, according to several clinical and observational studies published in the past decades, BCG may also increase the ability of the immune system to fight off pathogens other than the TB bacterium. Even a 2014 review ordered by the World Health Organization concluded that BCG appeared to lower overall mortality in children. (Although it rated the confidence in the findings as “very low”).
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There are many experts who agree with these findings. BCG vaccines primarily protect against tuberculosis, but it also affects the immune response against other pathogens, so it cannot be ruled out that it may also provide some protection against the coronavirus, said Viktor Müller, a research associate at the Faculty of Science at Eötvös Loránd University, to news site Magyar Hírlap.
He added that the BCG vaccine might prove to be effective against Covid-19 due to the fact that the tuberculosis bacterium was such an important pathogen in human evolution that we specifically adapted to it, so encountering the bacteria (or the vaccine) might be able to re-calibrate the “general sensitivity level” of our immune system in the long run.
Taking a look at countries that never used compulsory vaccination could further strengthen the hypothesis of the beneficial effects of the BCG vaccine. As an article by news site Válaszonline highlights, if we take a look, we find that Belgium is the first, while the Netherlands is the third most affected country in the world in terms of Covid-19 mortality rate per capita. It is not mandatory in either country to have a BCG shot.
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In contrast, if we observe the countries where all newborn children are still being vaccinated today- there are 11 such states in Europe (Bulgaria, Croatia, Estonia, Greece, Hungary, Ireland, Latvia, Lithuania, Poland, Portugal, Romania), and none of them are among the most infected countries.
However, many argue the reliability of the studies while also emphasizing that taking a look at related data without considering much of its context can also be greatly misleading.
There is no evidence that the BCG vaccine protects people against infection from the COVID-19 virus, the WHO said in a statement back in April. According to the organization, three documents were found in which the authors compared the incidence of COVID-19 cases in countries where the BCG vaccine is used with countries where it is not used. They observed that countries that routinely used the vaccine on neonates had less reported cases of COVID-19 to date.
However, as the statement also pointed out, these studies show significant differences due to the population characteristics of the country, the proportion of coronavirus tests performed, and the stage of the pandemic in that country; thus, such ecological studies and their subsequent conclusions are prone to significant distortion due to many confounding factors.
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In the absence of evidence, the WHO does not recommend BCG vaccination for the prevention of COVID-19.
Moreover, as the earlier cited Válaszonline article points out, the empirical country data also conceals many anomalies.
One such anomalous figure is the mortality rate in the United Kingdom. It was mandatory to be vaccinated in the country between 1953 and 2005, so in theory, similar to Hungary, only those above the age of 67 are not partially immune to the novel coronavirus. However, in terms of mortality rate, the contrast between the Hungarian and British data is striking.
The difference between Hungary and Austria cannot really be explained either, as until 2005, vaccination was mandatory there as well. However, the mortality rate per 1 million capita is 67 in Austria while it is only 35 in Hungary.
All in all, even though many studies show promising results, there is currently not a sufficient number and reliable enough research available to be at ease during the pandemic. Thus, until a vaccine specifically developed against the novel coronavirus is created, we, unfortunately, have to keep washing our hands, wearing face masks, and continue practicing social distancing.
Featured photo by KárolyÁrvai/kormany.hu/MTI