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Source: The post is based on the article “Experts suggest updating vaccines for new variants. How does it work & what are the challenges?” published in Down To Earth on 7th July 202
What is the News?
Experts have recommended updating the vaccines to protect against emerging SARS-CoV-2 variants.
How are vaccines updated?
mRNA vaccines: For updating the mRNA vaccines, one needs to replace the existing antigen with a new antigen and this can be done with any new pathogen as well. Essentially, two key ingredients are required — genetic sequence of the spike protein from a new variant of concern and a DNA template to build the mRNA.
– The genetic sequence has already been published by scientists and is available. So, manufacturers need only to make the DNA template which is a three-day process.
– Hence, it’s easier to update mRNA vaccines compared to others. However, they are not the most widely administered vaccine across the world.
Viral Vector Vaccines: Updating viral vector vaccines such as Janssen by Johnson & Johnson and AstraZeneca by the University of Oxford is also possible. Here, genetic material from the COVID-19 virus is placed in a modified version of a different virus. Once this enters human cells, the immune system is triggered.
– The biggest potential issue with updating the viral vector vaccine is that people previously immunized with this vaccine will develop immune responses to the carrier viral vector that could reduce immunogenicity in future doses.
Protein-Based Vaccines: It has to first go through a similar step as the mRNA vaccine (update the sequence) but unlike the mRNA vaccines (which are ready to go into arms once the sequence is updated), a protein based vaccine has to undergo additional time-consuming steps to get cells in the lab to produce the protein and then that protein has to be purified and validated to be intact.