A similar dose of tuberculosis vaccine (BCG) may protect against SARS-CoV-2 infection, suggests a study conducted among hospital staff in the United Arab Emirates.
Information on this subject is provided by the medRxiv portal, which publishes the works of scientists before they are reviewed. Therefore, the results of these studies should be approached with great caution.
The authors of the study – scientists from the Emirates International Hospital in Al Ain in the United Arab Emirates and the University of Texas Southwestern Medical Center in Dallas (Texas, USA) recall that the role of the BCG vaccine – used against tuberculosis – in stimulating the so-called nonspecific immunity against other pathogenic microorganisms, not only mycobacterium tuberculosis. There is evidence that BCG vaccination increases the activity of the immune system against other pathogens.
During the COVID-19 pandemic, it has been reported that countries where children are vaccinated with BCG (due to the high risk of tuberculosis) have fewer cases of COVID-19 and fewer deaths from it. However, one study found that childhood BCG vaccination did not protect young people from SARS-CoV-2 infection.
In a recent study, Emirates International Hospital staff were offered a so-called a dose of vaccine against tuberculosis in early March 2020. This center is a center for testing for SARS-CoV-2 infection and treating patients with COVID-19. Hospital staff therefore have an increased risk of infection.
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The hospital staff who were offered vaccination came from Arab countries, India, East Asia, Africa and Europe. They were between the ages of 21 and 80. Among them were doctors, nurses, but also non-medical workers, including receptionists.
They were provided with comprehensive information on the BCG vaccine, possible side effects and the observations made so far about its potential protective effects against COVID-19. They all received this vaccine as newborn babies. Of the 280 people, 71 workers chose a booster dose.
All of them were tested for SARS-CoV-2 infection in the following months – April, May and June, as well as in the event of contact with infected patients or the appearance of symptoms of infection.
Until June 24, the group that received the BCG booster dose had not a single case of SARS-CoV-2 infection, while the group who had not been vaccinated (209 workers) had 18 cases of COVID-19, i.e. 8,6% ., of which 13 were symptomatic and five were asymptomatic. Before the detection of the infection, the employees did not undertake any risky activities outside the home, were not traveling, did not have an infected person among their household.
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According to the researchers, these results indicate that a booster dose of BCG could be effective in preventing COVID-19 in a population of healthcare workers who are at particular risk of the infection.
The authors of the study emphasize that this study had many limitations, such as the small number of people included in the study or the difference in the size of both groups. No data was collected on comorbidities or preparations used by workers to prevent infection.
Therefore, the widespread use of a BCG booster dose for the prophylaxis of SARS-CoV-2 infections cannot be recommended at present.
More clinical trials are needed to verify that the BCG vaccine provides protection against SARS-CoV-2 infection – to what extent and for how long.
BCG is called live vaccine – contains attenuated, i.e. weakened, bovine Mycobacterium bovis BCG. According to the National Institute of Public Health (PZH) on its website, this vaccine reduces the risk of severe tuberculosis in children in the form of disseminated disease, tuberculous meningitis or death in the course of tuberculosis. In some countries, experts recommend a booster dose of BCG to increase resistance to tuberculosis. (PAP)
Author: Joanna Morga
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