Corbevax Covid-19 Vaccine: What We Know About It | India News
Corbevax is a ‘recombinant protein subunit’, also known as a ‘receptor binding domain’ (RBD) vaccine. It has a two-dose schedule administered by intramuscular injection 28 days apart. It can be stored in a common refrigerator.
In the 1980s, scientists discovered how to combine DNA from two or more sources. This is called recombinant DNA technology. When the genetic code of a virus is inserted into a yeast cell, the yeast begins to produce virus proteins. Vaccine manufacturers use this process to produce protein subunit vaccines.
The coronavirus uses its spikes to adhere to human cells. Within a peak, a part called the ‘receptor-binding domain’ or RBD allows it to couple and infect cells. An RBD subunit vaccine such as Corbevax contains only the RBD proteins of the virus. Different protein subunit vaccines can use different parts of the virus.
Advantages of protein subunit vaccines
- Rather than the entire virus, they contain only the components that best boost the immune system.
- Including only a few specific parts of a virus minimizes side effects and vaccines are easier to prepare
- These vaccines are just as effective as whole cell vaccines, but they are much less likely to cause adverse reactions, ”says the US National Institute of Allergy and Infectious Diseases.
- Since these vaccines cannot cause disease on their own, they are also suitable for people with compromised immune systems.
- Another great advantage of using specific virus proteins is that these vaccines can be more stable than those containing whole viruses.
- Because the immune system is exposed to only a few parts of the virus, it may not respond strongly to the vaccine.
- Furthermore, the resulting immunity can be limited to antibodies that diminish with time.
- To overcome this weakness, protein subunit vaccines usually contain another substance, called an adjuvant, to strongly stimulate the immune system. Corbevax uses the adjuvant. ‘CpG 1018’ manufactured by USA-based Dynavax.
4 main types of viral vaccines
Complete virus: It contains viruses that cause disease, either weakened or killed. E.g. Covaxin
Viral vector: It contains an unrelated virus that delivers a genetic code to create specific parts of the virus that causes disease. E.g. Covishield
Protein subunit: It contains specific parts of the virus that causes disease for the immune system to recognize. E.g. Corbevax
MRNA: It contains only genetic material with instructions for making specific parts of the disease-causing virus. E.g. Pfizer vaccine