Why did I always want to have Covaxin instead of any other one ?

( My personal opinion, not one of those numerous meta analyses .)

Today, We are given the first dose of Covaxin. All the Health Care Workers got it. We didn’t have a choice.

Health care Workers in India got the Covid Vaccine free of cost and on a priority basis. This is an huge advantage. But this advantage has its own share of disadvantage. We got the vaccine as allotted. We didn’t have any option to pick and choose a brand of our liking.

by lot

But then I have always wanted to have an attenuated whole cell vaccine and I got this Covaxin.

The Covaxin candidate was developed by Bharat Biotech (BBIL) in collaboration with the National Institute of Virology (NIV). NIV isolated a strain of the novel coronavirus from an asymptomatic Covid-19 patient and transferred it to BBIL early in May. The firm then used it to work on developing an “inactivated” vaccine — a vaccine that uses the dead virus — at its high-containment facility in Hyderabad.

Indian Express

“Once the vaccine is injected into a human, it has no potential to infect or replicate, since it is a killed virus. It just serves to the immune system as a dead virus and mounts an antibody response towards the virus.”

In contrast, the rest of the world concentrated on somehow getting a bit of the virus- only the small spike protein in this case into our system. That should effectively block the spike protein and successfully prevent the virus from entering into humans. While Pfizer (US-German) and Moderna (US-France) chose the mRNA platform for this, the Oxford (UK) and Sputnik ( Russia) preferred a viral vector to achieve the Goal. The target is uniformly similar- The spike protein.

Then somewhere in UK, the spike got changed

The virus mutated into a more infectious agent. It sharpened its weapon of penetration- the Spike.

That is definitely going to affect immunogenicity of all the four agents. Whatever they may claim, only time will tell the truth. Pfizer has already accepted the fact and has claimed that they will take only 3 months to come out with a modified version. That is the advantage of computer modelling of the mRNA platform. These mRNA people can give you a designer baby what to speak off a designer spike. Though at a price.

Oxford says that the mutant spike protein still retains few original antigens despite the 3 mutations already detected. But then the virus also learns very fast. Once a million people are injected with the spike antigen, the virus is going to change its spike protein completely. That is what Darwin’s “survival of the fittest’ doctrine states.

Now think.

If I have taken the whole virus which has 29K nucleotides coding for 29 protein antigens in all, Its antigenicity will be unaffected till plenty of mutations. That is a one in million chance and I could safely pass one or two decades.

The RNA genome of SARS-CoV-2 has 29,811 nucleotides, encoding for 29 proteins.

source: C&EN

At least that is what we have been taught in our immunisation class. An attenuated or killed organism is always a better candidate than any part of the virus. That is the principle behind Salk’s Killed Polio vaccine. An injected Polio vaccine is more immunogenic than the Oral Polio despite all those theories of secretory IgA antibodies etc. While Developed nations always relied on Injected Polio vaccine, we in India have recently switched from 16 dose oral Polio to 3 dose IPV. A more accurate option.

I have had the the ring side opportunity to see the evolution of India’s Polio Eradication program over 35 years from 1985 till 2020. That is the exact period of my Pediatric and immunisation career. I have seen our OPV program starting with the initial “3 doses+ one Booster” schedule in 1985 to 5 dose schedule. Around the turn of century, In front of my eyes, they went on adding 2 doses of Pulse Polio every year till a 5 year kid was put on sixteen doses of OPV. Result was never 100%. All the while the developed nations like USA and Germany used to get 100% immunity with  only 3 doses of killed Polio vaccine. Since then I have a healthy respect for all killed vaccines especially the mutating one. Their only problem is adverse reaction. The more abundant is antigen, the more antigenicity and also more hypersensitivity.

Anyway, I’m doing fine and don’t feel like getting one of those rare  adverse events.

That means I will be blessed with a robust immunity.

Congratulating all those who have had the whole cell than a bit of spike protein in their system.