Bill and Melinda Gates Foundation sponsored $10 million for research to determine whether an old vaccine could be used to combat COVID-19.
This is called BCG and what could be its possibility to battle the new disease?
What is BCG?
BCG is a vaccine used to provide protection against tuberculosis. BCG or Bacillus Calmette-Guerin was developed in the early 1900s by two scientists Leon Charles Albert Calmette and Jean-Marie Guerin,
Primarily, the vaccine was made out of a bacteria found in cows related to the tuberculosis bacteria. With the scientific name Mycobacterium bovis, it was synthesized in a laboratory that allowed it to develop properties that could withstand the threat of tuberculosis.
It was used to vaccinate children, the cohort where most of the cases of tuberculosis have been recorded. It effectively protected roughly 86% of its recipients. On the other hand, adults were protected at a 50% rate.
Despite its consistency, it gave a positive effect in the long run. The long-term effect of the vaccine has given the children a higher immunity against various respiratory diseases. This is called “trained immunity”.
The difference between immune memory and trained immunity
Our body is home to two kinds of cells: innate cells and adaptive cells. The former respond immediately to external microbes that cause disease while the latter respond slowly.
Adaptive cells respond to microbes and ‘remember’ them after the first encounter. This allows them to act against it for any possible infections in the future.
This process is referred to as “immune memory”. This process prepares our immune system for any re-infection caused by microbes that affected us in the past.
For a long time, epidemiologists and scientists utilise immune memory to create vaccines. Meanwhile, the use of trained immunity has proved that innate cells can be trained to provide the immune system a certain capacity to react quickly with the infections.
One example would be BCG. It is more likely to prepare the immune system to combat any possible diseases such as SARS-CoV-2 and others in the future through trained immunity.
BCG as protection?
Further studies are done in Melbourne to assess the capacity of BCG to combat COVID-19. For now, let’s take a look at some of its interesting features.
One of the features of BCG is that it enhances the immune system. In the past, it was used as well in therapies for cancer and melanoma treatment.
Second, it has positive effects on the lungs. This is proven by the previous usage of the vaccine for children.
Lastly, BCG has established itself to battle viral infection effectively. One study shows that human volunteers who received BCG have limited viral infections to them.
Nevertheless, the vaccine also has its side effects. For instance, it can cause blisters upon injection. Also, since it is a live bacterium, it is prone to become a disease especially for people who have immunodeficiency.
Undergoing clinical trials
Randomised clinical trials are underway to assess whether BCG could be a vaccine for COVID-19.
Researchers from Australia and the Netherlands collaborated to test the vaccine. They will give it to frontline health workers, who are at the highest risk of being infected by COVID-19.
Moreover, successive research is needed to completely determine the potency of the vaccine as well as to the mass production of it considering its limited supplies.
Scientists should understand additional issues concerning its duration too. Preliminary tests found out that it could not ensure strong protection as compared to other vaccines.
In its application, it could be well used for people who are at a high risk of infection.
Although this development is a step towards progress, the real and holistic vaccine for COVID-19 may be produced months or years from now.
This repurposing of former vaccines could guarantee protection for the people, especially those who are prone to infection in the meantime.