How effective would be our vaccines against the Covid Variant strains ?

We always knew that the Covid virus is going to mutate. In adverse situations, it is going to change its structure to survive against such odds. That is Darwins law of Natural Selection. It is called “the law of the Survival of the fittest.”

Andreano E et al. in an experiment in Italy, serially passed the human-cov2 virus through convalescent plasma. The plasma fully neutralised the virus till 7th generation. By 73rd day the virus showed a mutation in the receptor binding domain (RBD) of spike protein. By 80th day the virus was completely resistant by developing three mutations in its spike protein.

From the Monoclonal Antibody Discovery (MAD) Lab,Fondazione Toscana Life Sciences, Siena, Italy
https://doi.org/10.1101/2020.12.28.424451
authors: Andreano et al

So what will happen, once millions of people are vaccinated with these spike targeting vaccines ?

The results: We have already seen two changed virus strains now. The UK variant and the South Africa variant.

The genome of the UK-variant has seventeen mutations, eight of which were found in the spike receptor-binding domain (RBD). This domain mediates the attachment of the virus to the angiotensin converting enzyme 2 (ACE2) receptor on the surface of human cells.

The spike of UK variant changed its 614 domain.

The majorities of vaccine candidates that of Pfizer, Oxford target the D614G epitope of the spike protein. While the Moderna and Pfizer use the mRNA platform, Oxford (UK) and Gamaleya ( Russia) labs use viral vector to deliver the spike protein unto human bodies. Common sense tells us that the the new variant viruses will be able to escape them.

ICMR and NIV Pune have come out with the result of their own study involving COVAXIN.

Covaxin is an inactivated whole-virion SARS-CoV-2 vaccine BBV152. It is not dependent on the spike protein route. Instead a killed whole virus was injected into us.

They have collected Sera from 38 vaccine recipients from their phase-II trial. The sera is applied to both the old virus and two variant virus strains with the characteristic N501Y substitution of the UK-variant isolated from UK returnees.

Their study highlighted comparable neutralization activity of their serum ( derived from vaccinated individuals) against variant as well as the original SARS-CoV-2 strains.

What is the significance ?

Serum from the Covaxin vaccine recipients could neutralise the UK-variant strains. That effectively discounts the uncertainty around potential escape.

“It was reassuring from the PRNT50 data generated in our laboratory that the indigenous BBV152/ COVAXIN™, following its roll out in vaccination program, could be expected to work against the new UK-variant. It is unlikely that the mutation 501Y would be able to dampen the potential benefits of the vaccine in concern.” quoted ICMR.

bioRxiv preprint doi: https://doi.org/10.1101/2021.01.26.426986; 

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