BCG: Will The Old Vaccine Help Fight The New Coronavirus?

BCG: Will the old vaccine help fight the new coronavirus?

March 24 is International Tuberculosis Day. One of the most important tools for the prevention of this disease is the BCG vaccine. A team of scientists from four countries will soon begin researching this vaccine in an unusual context. It is planned to test whether the drug can enhance the body's defenses against the new coronavirus infection COVID-19 and other infections.

Photo: CC0 Public Domain / Photo: CC0 Public Domain

The new study is expected to involve nurses and doctors who have a higher risk of contracting airborne infections than the average population. The study will also cover older people, because they are more likely to have dangerous consequences of infectious diseases.

What is this vaccine

BCG vaccine contains a weakened strain of Mycobacterium bovis, the causative agent of "bovine tuberculosis". It was named after the French microbiologists Albert Calmette and Camille Guerin. In many countries, including Russia, children are vaccinated in her in the first year of life. Science points out that the vaccine is "safe and cheap, but far from perfect: it prevents up to 60% of TB cases in children, with a wide range of rates across countries."

Wide range of protection

Typically, vaccines help the body develop immunity against a specific pathogen (bacteria or virus). The peculiarity of BCG is that it increases the body's resistance not only against the causative agent of tuberculosis. Danish scientists have published a series of studies, the most important conclusion of which is that the anti-tuberculosis vaccine prevents about 30% of all infections within the first year after vaccination. This pattern also applies to viruses.

The “miraculous” findings of the BCG vaccine have been criticized, but a review published by WHO in 2014 argued that the vaccine reduced all-cause mortality in children (however, it indicated that the level of available evidence was low). A 2016 review published by The BMJ was more positive, but pointed to the need for new qualitative research.

Since then, the clinical evidence for BCG's benefits has strengthened. Infectionist Mihai Netea of the University of Nijmegen Medical Center described the effects of the vaccine on immunity. According to him, the BCG vaccine can be kept alive in human skin for several months. It spurs not only the specific memory of immune cells against tuberculosis. Scientists claim that it stimulates immune cells in general for a long time. Netea and his colleagues called this phenomenon "trained immunity." Their 2018 randomized study found BCG vaccination could protect against attenuated yellow fever virus.

New research

Mihai Netea and his colleague at the University of Athens, Evangelos Giamarellos, have begun a study in Greece to show whether the BCG vaccine reduces the incidence of various infections in the elderly. A similar study is planned for the Netherlands.

The new studies were designed before the new coronavirus emerged. Netea believes the current pandemic will help unlock the potential of the BCG vaccine in greater detail.

Scientists from the University Medical Center Utrecht, the University of Melbourne (they will test the effectiveness of BCG in doctors) and the University of Exeter (they will test the vaccine in the elderly) joined Nethea and Giamarelos.

Inspired by the example of Nethea, scientists from the German Max Planck Institute said they would conduct their research with the participation of health workers and the elderly. It will use a genetically modified vaccine that has not yet been approved for immunization against tuberculosis.

Eleanor Fish, an immunologist at the University of Toronto, told Science in a commentary that the vaccine will probably not be able to fully deal with the new coronavirus. But most likely she will be able to mitigate its impact on humans. The specialist noted that she herself does not mind getting vaccinated.