Inactivated Virus Vaccine in Focus for Covid-19

• 17 Apr 2020

Why in News

Recently, researchers from the Centre for Cellular and Molecular Biology (CCMB) have started developing an inactivated virus vaccine for the novel coronavirus (SARS-CoV-2).

Key Points

• Vaccination is thought to be the most effective and sure way to arrest the progress and deadly effect of the virus.
• Inactivated vaccines are known for their safety and easy production.
• Inactivated Vaccines
  
  • Active pathogens are grown in large numbers and then killed either by a chemical or heat. Although the pathogen is killed, or made to lose its reproduction capacity, various parts of the pathogen are intact. E.g The antigen (the chemical structure) that is recognised by the immune system is left unimpaired.
  • When this dead microbe is introduced in the body, the immune system is tricked to respond by producing antibodies against specific antigens still left intact, without knowing that the pathogen is defective.
  • As the pathogen is dead, it cannot reproduce nor cause even a mild disease. Thus, it is safe to administer to even people with lesser immunity, like the old and those who have comorbidity.
  • Inactivated polio vaccine and the rabies vaccine are made this way.
• Benefit: If a large amount of coronavirus is grown and inactivated, that will be material for candidate vaccines to be injected.
• Challenges: The important technological challenge is growing the coronavirus outside of the human host.
  
  • As the novel coronavirus has evolved to life on human cells, locating the right source of the cell line to grow the virus outside of the human body is key to this technology.
• CCMB is using the epithelial cell line from African green monkeys to artificially grow and harvest the deadly virus.
• The cells will be observed and if the cells show changes, including dying of cells and release of the virus, then the culture is positive.
• Finding a right cell growing technology for the novel coronavirus will also help in drug development.

Other Types of Vaccine

Live-attenuated vaccines

• Live vaccines use a weakened (or attenuated) form of the germ that causes a disease.
• Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response.
  
  • Just one or two doses of most live vaccines can give you a lifetime of protection against a germ and the disease it causes.
• The limitation of this approach is that these vaccines usually cannot be given to people with weakened immune systems
• Live vaccines are used against: Measles, mumps, rubella (MMR combined vaccine), Rotavirus, Smallpox among others.

Subunit, recombinant, polysaccharide, and conjugate vaccines

• They use specific pieces of the germ — like its protein, sugar, or capsid (a casing around the germ). They give a very strong immune response.
• They can also be used on people with weakened immune systems and long-term health problems.
• These vaccines are used to protect against: Hib (Haemophilus influenzae type b) disease, Hepatitis B, HPV (Human papillomavirus), Pneumococcal disease among others.
• Toxoid vaccines
• Toxoid vaccines use a toxin made by the germ that causes a disease. Toxoid vaccines are used to protect against: Diphtheria, Tetanus

Source: PIB