BCG Vaccine and its possibilities for COVID-19

Ever wondered what that small scar on your upper arm/thigh was from? That’s right, it’s from the BCG vaccine your parent gave you when you were an infant. But why is this vaccine important enough for everyone to have it?

You see, the whole concept of a vaccine is to build your immunity against specific pathogens- so even when you get an infection in the future, you won’t be affected because your white blood cells will remember the pathogen from when you took the vaccine; then recognize and kill it. And so, among other vaccines, the BCG vaccine is given to immunize you against Tuberculosis.

BCG, short for Bacillus Calmette-Guérin, is a live attenuated vaccine given intradermally for Tuberculosis, which is caused by the bacteria Mycobacterium tuberculosis.

But lately, there have been reports that claim this BCG vaccine can protect an individual from COVID-19, the virus that is causing the current pandemic. Sounds strange, does it not? How could a centuries-old vaccine specific for bacteria be effective against… a virus? Is it then a baseless hoax being spread?

Surprisingly, it is not! Turns out, BCG vaccine has some off-target aspects to it that could give your general immune system a long-forgotten boost in order to protect you from contracting the viral disease. Even though it does not, logically, have specificity against SARS-CoV-2 and cannot completely cure the disease caused by it, what it can do is trigger for an increase in IFNγ and IL-10 (immunomodulatory protein molecules known as cytokines) in patients.

IFNγ induces anti-viral immune responses and is capable of reducing viral load in the face of a viral infection. IL-10, on the other hand, fights against tissue damage- thus making sure the patient’s lungs aren’t affected or weakened by the infection. All of this simply makes sure your body’s overall immune system is amped up to fight against a viral infection as front-line defences until proper COVID-specific treatment is given.

A clinical trial was done on elderlies that proved this efficacy, and thus gave some people hopes about getting re-vaccinated with BCG. But it should be noted that this is not for people who have an already weakened immune system- because that will cause adverse effects where the recipient may even contract TB from the vaccine itself, instead of being protected from SARS-CoV-2.

Although this is not in any way a mandatory treatment regimen for COVID-19, it is still important to know BCG’s effects regarding COVID-19. This is so you can responsibly make decisions and take steps to keep yourself safe from the pandemic. Besides, BCG is in great shortage in terms of supplies worldwide- so it’s best to keep it for the people who really need it, rather than getting re-vaccinated in mass for a possible protection, which in my opinion, can easily be obtained from just simple social distancing and quarantine. Remember, this is a protection, not a cure!

— x —

This article was written by:

Waziha Labiba Khan,
Microbiology Researcher, Business and Clinical Development Team,
Renata Limited.

For any queries, please email: waziha.lk@yahoo.com

— x —

References:

1. Inserm. (2020, April 3). The BCG vaccine against COVID-19 — really? Retrieved from https://presse.inserm.fr/en/the-bcg-vaccine-against-covid-19-really/38920/
2. Newman, T. (n.d.). COVID-19: TB vaccine to be trialed in healthcare staff. Retrieved from https://www.medicalnewstoday.com/articles/covid-19-could-tb-vaccine-offer-protection
3. O’Sullivan, K. (2020, April 6). Coronavirus: More ‘striking’ evidence BCG vaccine might protect against Covid-19. Retrieved from https://www.irishtimes.com/news/health/coronavirus-more-striking-evidence-bcg-vaccine-might-protect-against-covid-19-1.4222110
4. Pti. (2020, April 4). US scientists link BCG vaccination with fewer coronavirus cases, Indian scientists hopeful but cautious. Retrieved from https://economictimes.indiatimes.com/news/science/us-scientists-link-bcg-vaccination-with-fewer-covid-19-cases-indian-scientists-hopeful-but-cautious/articleshow/74931591.cms
5. Rabin, R. C. (2020, April 3). Can an Old Vaccine Stop the New Coronavirus? Retrieved from https://www.nytimes.com/2020/04/03/health/coronavirus-bcg-vaccine.html
6. Savarin, Carine, Bergmann, & C., C. (2018, December 6). Fine Tuning the Cytokine Storm by IFN and IL-10 Following Neurotropic Coronavirus Encephalomyelitis. Retrieved from https://www.frontiersin.org/articles/10.3389/fimmu.2018.03022/full
7. Wardhana, Datau, E. A., Sultana, A., Mandang, V. V., & Jim, E. (2011, July). The efficacy of Bacillus Calmette-Guerin vaccinations for the prevention of acute upper respiratory tract infection in the elderly. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/?term=wardhana,+BCG,+elderly