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COVID-19 Vaccines

What disruptive technologies are being used for COVID-19 vaccines?

By Apollo 24/7, Published on - 20 October 2020

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The world as we knew until last year has changed completely, owing to the emergence of the Coronavirus disease. We are witnessing the worst global public healthcare crisis since 1920. The pandemic has resulted in an unprecedented loss of life and economic damage. As of now, a safe and effective vaccine appears to be humanity’s only hope against the pandemic.

What is a vaccine?

A vaccine is a kind of medicine that triggers the body’s immune system to recognize and fight disease-causing microorganisms. It works by training the immune system to produce antibodies that are otherwise produced when exposed to the disease. These antibodies are specialized proteins that fight against disease-causing virus and bacteria. Most of the vaccines usually contain only killed or weakened forms of microorganisms like viruses or bacteria. As a result, they do not cause the disease. A vaccine is usually administered orally or via injection.

History and overview of vaccines

In 1796, Dr. Edward Jenner created history by inoculating a 13-year old boy with vaccinia virus (cowpox). The inoculation made that boy immune to smallpox, a deadly and infectious viral disease. The technique of vaccination was further developed in the 19th century by Louis Pasteur who used killed bacteria and virus to develop vaccines for anthrax and rabies, respectively.
According to the WHO, mass vaccination (or immunization) prevents 20-30 lakh deaths annually from diseases like polio, influenza, measles, pertussis, diphtheria, and tetanus. Today, vaccines exist for more than 20 different illnesses and infections.

COVID-19 vaccines: Technologies and platforms used

While there have been traditional platforms used for developing vaccines for existing diseases, new and powerful technologies are speeding up the development of various COVID-19 vaccine candidates. Globally, pharma companies and research institutes are pursuing different approaches and technologies to deliver a COVID-19 vaccine.
(I) Traditional platforms
  • Attenuated live virus
An attenuated live virus vaccine uses a weakened (or attenuated) form of the virus that causes the disease. The virus is alive but has been weakened so it can replicate in the body several times and generate an immune response without causing the disease. The vaccine triggers an immune response similar to a natural infection. This vaccine provides long-term immunity. Measles, yellow fever, mumps, rubella and smallpox are some of the conditions for which attenuated live virus vaccines are used.
  • Whole Inactivated virus
Under this approach, a vaccine is produced by inactivating a strain of the virus by using heat or chemicals. When administered, a whole inactivated virus vaccine induces a robust antibody response. Compared to live attenuated virus vaccines, these vaccines generally lead to fewer side effects. However, the development of these vaccines requires large quantities of virus. Influenza, hepatitis A and rabies are some of the conditions for which whole inactivated vaccines exist.
  • Protein subunit
In this approach, a specific protein is isolated from the virus, and used in the vaccine. The protein induces a strong and protective immune response. Vaccines developed via this approach have fewer side effects than attenuated live virus vaccines. Protein subunit vaccines are used to vaccinate against influenza.
(II) New or next generation platforms
  • Replicating or non-replicating viral vector
In these vaccine types, researchers use just a part of the virus (e.g., the protein part) and isolate its gene from the protein. This gene is then introduced into a completely different virus which is harmless (e.g., the common cold). The ‘safe’ virus triggers an immune response by delivering the gene of the Coronavirus protein. The modified virus does not replicate, and it doesn’t cause the infection itself. As of now, Ebola is a condition for which such an approved vaccine exists, and there are other vaccines being developed using this technology, notably various HIV vaccines for AIDS.
  • DNA Vaccines
A DNA vaccine uses the genetic information from a virus to trigger the body’s immune system. When the DNA vaccine is administered to an individual, the cells in his or her body make a viral protein which mimics the actual virus. The immune system identifies the protein as a foreign body and kills it. As a result, the body develops immunity against the actual virus.
  • RNA vaccines
RNA vaccines are somewhat similar to DNA vaccines. They inject the virus’s genetic material (mRNA) into human cells. These genes are treated as instructions for tricking the body to create proteins that look like the coronavirus. The proteins stimulate the immune system and provide protection against the virus.
Currently, there are no DNA/RNA vaccines approved yet for medical use in humans. Both RNA and DNA vaccines are likely to offer strong cellular immunity and can be developed rapidly. If either of the Moderna or Pfizer vaccines is approved in the next few weeks, it will be the first-ever approved RNA vaccine, paving the way for several more.

Top 10 COVID-19 Candidate Vaccines

As of October 2019, only 10 out of 44 candidate vaccines in clinical trials have entered phase III trials. Huge expectations have been pinned on these top 10 candidates. Four of these candidates are non-replicating viral vector type vaccines, three are inactivated vaccines, two are RNA vaccines and one is protein subunit vaccine.

COVID-19 Vaccine Developer

Vaccine Type

Moderna/NIAID

RNA

University of Oxford/AstraZeneca

Non-Replicating Viral Vector

Sinovac

Inactivated

Gamaleya Research Institute

Non-Replicating Viral Vector

BioNTech/Fosun Pharma/Pfizer

RNA

CanSino Biological Inc./Beijing Institute of Biotechnology

Non-Replicating Viral Vector

Novavax

Protein Subunit

Janssen Pharmaceutical Companies

Non-Replicating Viral Vector

Wuhan Institute of Biological Products/Sinopharm

Inactivated

Beijing Institute of Biological Products/Sinopharm

Inactivated

 
Conclusion
Researchers believe that a safe and effective COVID-19 vaccine is within the reach of the scientific community. The past successes of vaccines offer a ray of hope to humanity that is eagerly waiting for a vaccine to defeat the pandemic. However, it will take a couple of more months to develop and test all these candidates thoroughly. Until then, the safest and most effective public health tool against COVID-19 is to wear masks, follow physical distancing and social hygiene guidelines.
Register yourself with the vaccine tracker for the latest updates on COVID-19 vaccines.

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