More than a hundred different teams of scientists are developing vaccines for COVID-19. Developing vaccines from scratch is not the fastest option for stopping the ongoing pandemic no matter how effective they will be, but it is does constitute the desirable long-term solution.
The time required to develop and deploy a safe and effective vaccine is typically 10-15 years (Figure 1). However, for COVID-19, the attempt is to compress to over a year.
Vaccine development requires extensive planning regarding the following:
- vaccine design
- vaccine production and purification
- pre-clinical testing in animals (to ensure some safety in humans)
- multiple phases of clinical trials in humans (phase 1 for safety as well as phases 2 and 3 for efficacy).
Various strategies used for vaccine development are live attenuated or inactivated viruses, virus-like particles or other protein-based approaches, viral vector–based vaccines or nucleic acid–based vaccines.
This course covers types of vaccines and strategies being used to create vaccines to fight COVID-19.
Types of Vaccines
Whole virus vaccine
It is also known as Inactivated and Live inactivated vaccines. Weakened or live vaccines are attenuated form of the germ that causes a disease.
Inactivated vaccines use the killed version of the germ that causes a disease. However, they tend to provide a shorter length of protection than live vaccines, and require boosters to create long-term immunity.
The vaccine also stimulate a strong immune response against the microbial antigens displayed on cell surfaces. It is an inexpensive vaccine.
Viral vector vaccine
Vaccine that use a virus to deliver coronavirus genes into cells. There are two types:
- those that can still replicate within cells (replicating)
- those that cannot (non- replicating) because key genes have been disabled.
When administered in the body, a protective immune response occurs against the pathogen.
It is produced through recombinant DNA technology. Yeast or other cells can be engineered to carry a virus’s gene.
|Whole virus vaccine||DNA vaccine||RNA vaccine||Viral vector vaccine||Protein-based vaccine||Recombinant vaccine|
|Definition||Modifies entire virus to provoke immune response||Uses part of genetic code of coronavirus||Based on delivering mRNA into cells||Use of virus to deliver coronavirus genes to cells.||Uses coronavirus protein||Produced through recombinant DNA technology|
|Other names||Inactivated and Live attenuated Vaccines||Genetic vaccine||RNA vaccine||Adenovirus vector vaccine||Virus-Like Particle vaccines||Recombinant Vector vaccine|
|Conventional examples of vaccine||Influenza, chickenpox, MMR||
|Under clinical trials for MERS and a few other diseases||
H.I.V. & Ebola
|HPV||Shingles and Hepatitis B|