Self-replicating mRNA Covid-19 vaccines

Contact Counsellor

Last Updated27/04/2022

A self-amplifying mRNA vaccine has shown promising results against Covid-19 in ongoing phase 1/2/3 trials.
The vaccine, ARCT-154, has been developed by Arcturus Therapeutics Holdings, based in San Diego, California, and its trials are in progress in Vietnam.
It offered 95% protection against severe Covid-19 and death, and 55% against Covid infection, Arcturus said in a press release.

mRNA vaccines tricks the body into producing some of the viral proteins itself.
They work by using mRNA, or messenger RNA, which is the molecule that essentially puts DNA instructions into action. Inside a cell, mRNA is used as a template to build a protein.

This is image title

To produce a mRNA vaccine, scientists produce a synthetic version of the mRNA that a virus uses to build its infectious proteins.
This mRNA is delivered into the human body, whose cells read it as instructions to build that viral protein, and therefore create some of the virus’s molecules themselves.
These proteins are solitary, so they do not assemble to form a virus.
The immune system then detects these viral proteins and starts to produce a defensive response to them.

mRNA vaccines are considered safe as mRNA is non-infectious, non-integrating in nature, and degraded by standard cellular mechanisms.
They are highly efficacious because of their inherent capability of being translatable into the protein structure inside the cell cytoplasm.
Additionally, mRNA vaccines are fully synthetic and do not require a host for growth, e.g., eggs or bacteria. Therefore, they can be quickly manufactured inexpensively to ensure their "availability" and "accessibility" for mass vaccination on a sustainable basis.

This is image title

Vector vaccine:
- In this type of vaccine, genetic material from the COVID-19 virus is placed in a modified version of a different virus (viral vector).
- When the viral vector gets into your cells, it delivers genetic material from the COVID-19 virus that gives your cells instructions to make copies of the S protein.
- Once your cells display the S proteins on their surfaces, your immune system responds by creating antibodies and defensive white blood cells.
- If you later become infected with the COVID-19 virus, the antibodies will fight the virus.
Protein subunit vaccine:
- Subunit vaccines include only the parts of a virus that best stimulate your immune system.
- This type of COVID-19 vaccine contains harmless S proteins.
- Once your immune system recognizes the S proteins, it creates antibodies and defensive white blood cells.
- If you later become infected with the COVID-19 virus, the antibodies will fight the virus.

Prelims Takeaway

Mains Track

Q. mRNA vaccines can prove to be a gamechanger in the way the vaccines are administered to patients. Comment.