ALL YOU NEED TO KNOW ABOUT THE SECOND WAVE OF COVID-19!!

 We all very well know that the second wave of COVID - 19 with its double/triple mutants (not only these but many more variants are being reported) are evolving with a motive of evading human immune responses, spreading like wildfire today, with few cases being asymptomatic to cases having totally different symptoms than the ones which the first wave taught us. The public are understandably eager to know what the future will hold with the cases surging in rapid fire.

So first of all what is a mutation?

A mutation is a change in a genetic sequence. Mutations occur in nucleotides, which are the basic substances that make up RNA and DNA. The amino acid sequence is determined by the sequence of these nucleotides in RNA and DNA. The mutations in a particular viral genome can change these amino acid sequences, which further can change the structure of the protein produced by the life form. 

Well, these mutations can be of 2 types - deletion and substitution. Deletions are those which cannot be autocorrected by a proof -reading mechanism whereas substituitions are those that can be autocorrected by a proof - reading mechanism. Now what is this proof - reading mechanism? Well, the SARS - CoV - 2 virus has a proof - reading mechanism which is implemented through a non structural protein called NSP 14. 

Mutations are actually expected, but not all of them are of apparent benefit or purpose to the virus. The most notable part of the spike protein of the novel coronavirus is the Receptor Binding Domain (RBD), which serves the purpose of attaching the SARS - CoV - 2 virus to specific human receptors on some cells, to infiltrate those cells. 

Most mutations generally don't alter the virus's behaviour. However, when some mutations trigger changes in the spike protein, these result in changed viral attributes. There are particular amino acid residues such as 319-541 especially between 438 and 506 wherein if the mutations occur in these specific residues, they can significantly impact the virus's transmissibility, infectiousness, severity and its immunity evading potential. 

Now coming to the vaccine part.

Many were confused about the probable utility of the COVID - 19 vaccines in India - Covishield and Covaxin, against the new variants circulating. Variety of questions came up like - Should we continue using Covishield in places where the B.1.1.7 variant and other new variants are emerging? How efficacious would it be? Do we have other options? Will Covaxin be more efficacious? 

Apparently, the B.1.1.7 variant is not usually considered to belong to an immune - escape lineage. And most new vaccines such as Novavax in certain efficacy trials, Pfizer - BioNTech and Moderna vaccines in laboratory studies have been tested against this variant according to studies. 

A point to be remembered is that the B.1.351 variant contains E484K point mutation, that is, a substitution that has also been found in many samples around India, with this mutation being involved in the 'double mutant'. Since the 484 residue is strongly associated with immune evasion, the chances of Covishield providing significant efficacy against symptomatic illnesses is pretty much less, but yes of course, it can retain an extent of reasonable protection against severe disease and death owing to good T - cell immunity. 

I strongly feel that there is an urgent need to perform studies such as Covishield's efficacy against different variants to understand the reinfection rates among people who have received either Covaxin or Covishield. Do let me know your thoughts too on this topic in the comments ! 

A topic of mutant discussion can be a long interesting one when going into the depths of their morphological and physiological studies. Do let me know if you need any other information regarding mutants or anything else in the comments and I would definitely try posting about them in my next post. I will definitely try putting in more information about such mutants and their capabilities in my next post after reading a little more deeply about significant particular mutants. I have already posted one article long back about the D614G variant.. Do give that also a read, if you haven't yet !