Thread by @NavroopSingh_

Summary of Various studies on Vaccines & on various strains of SARS-Cov-2 :

Original SARS-CoV-2 strain from Wuhan

Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection - Nature Peer reviewed study of 17th May 2021

Nature Study on Original Wuhan Strain of SARS-CoV-2

>Novovax (Protein Sub Unit Vax Tops) - 98%
> Pfizer & Moderna - 95% after 2 Doses
> Sputnik - 95% 2 Doses
> COVAXIN - 80% 2 Doses
> AstraZeneca- 78% {2 doses after 8 weeks, post 12 weeks 90%]
> SINOVAC - 55% after 2 Doses

Effectiveness of COVID-19 vaccines against the B.1.617.2 variant - UK Study dt 22 May 2021

1) Effectiveness of COVIDSHIELD is 33% after one Dose Vs Delta variant. Pfizer too clocks same.

2) After 2nd dose on Delta Variant-

Pfizer - 87.9%
COVIDSHIELD - 59.8%

Neutralising antibody activity against SARS-CoV-2 VOCs B.1.617.2 (Delta Strain) and B.1.351 (Beta) by BNT162b2 vaccination (Pfizer Vaccine) - The Lancet Study

Pfizer Gets Neutralised by 5.8 Folds against the Delta Variant.

Lancet Study:

> Pfizer Vaccine Antibodies is significantly neutralised against Delta Variant B.1.617.2 upto 5.8 folds compared to 2.8 Folds against Alpha Variant B.1.1.7 & 4.9 Folds against the Beta Variant B.1.315

> Single Dose Pfizer gives very less protection against B.1.617.2 & B.1.315 compared to B.1.17. Two doses gives u sufficient protection but its far less than against Original strain that chances on Reinfection remain.

> Given the mutation of B.1.617.2 countries might have to rethink reducing the dosage time between two dosages as one dose gives insufficient immunity against the mutant strain.

> Also plan for Booster shots for Vulnerable section soon given B.1.617.2 neutralises Antibodies.

Neutralization against B.1.351 and B.1.617.2 with sera of COVID-19 recovered cases and vaccinees of BBV152 (COVAXIN) - ICMR Study dt 05th June 2021

The finding of the study demonstrated a reduction in neutralization titers with sera of COVID-19 recovered cases(3.3-fold and 4.6-fold) and BBV152 vaccinees (3. 0 and 2.7 fold) against B.1.351 and B.1.617.2 respectively.

Although, there is reduction in neutralization titer, the whole-virion inactivated SARS-CoV-2 vaccine (BBV152) demonstrates protective response against VOC B.1351 and B.1.617.2.

Lastly broad epitope coverage of an inactivated virus vaccine BBV152 decreases the magnitude of reduced neutralisation against emerging variants of SARS-Cov-2.

Now comes the study recent study of HCWs on COVIDSHIELD Vs COVAXIN which created a vociferous debate. Lets deal with it. This study came on 02nd June 2021 before ICMR study of COVAXIN Delta Variant on 05th June 2021 as stated above in thread.

Antibody Response after Second-dose of ChAdOx1-nCOV (CovishieldTM) and BBV-152 (CovaxinTM) among Health Care Workers in India: Final Results of Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) study - 02nd June 2021

The study showed:

> COVIDSHIELD produced 10 times more anti bodies titer than COVAXIN against Spike Protein

> Covaxin fares lower on Single Doses but does better on stopping breakthrough infection on two doses giving robust immunity.

Limitations of Study many of it stated inside it:

> Measurement of Antibodies on Spike Protein of Virus
> No measurement of Antibodies on N & M Proteins Virus
> No calculation of Th1 cell based immunity levels.
> Sampling Bias

Study Disclaims in Last para:

“Whether any real difference in inducing immunogenicity exists between two vaccines can only be meaningfully demonstrated through a head-to-head RCT.”

Now COVAXIN is an Inactivated Virion Vaccine which uses a dead SARS-CoV-2 Virus induced in body having Spike, N & M Protein inducing not only Anti Bodies titter but also Th1 cellular immunity.

While COVIDSHIELD is Adenovirals vector creating response of Body to Spike Protein thus making antibodies & Th2 humoral immune response.

The two are different class of vaccines & thus incomparable.

COVAXIN uses adjuvant Alhydroxiquim-II to boost immune response and longer lasting immunity.The technology is being used under a licensing agreement with Kansas-based ViroVax.

COVAXIN uses Imidazoquinoline class of adjuvants (TLR7/8 agonists), which are known to induce Th1 Cell based based response which further reduces the risk of ADE (Anti-Body Dependent Enhancement).

Th1 skewed immune response of whole virion inactivated SARS CoV 2 vaccine and its safety evaluation in this case its BBV152 i.e. COVAXIN (Study done in November 2020 & published in April 2021)-

In conclusion, we believe that the ability to induce Th1-skewed immune response and the presence of conserved S and N protein in inactivated vaccine candidate formulated in Algel-IMDG would help to combat other SARS CoV-2 variants.

In our findings, we also observed high binding titers with a 100% seroconversion toward S1, RBD, and N protein. In short COVAXIN a whole inactivated Virion Vaccine provide wholesome immunity against S, N & M Protein of Virus as well as Th1 Immune Cell memory (T&B Cells).

This is the breakdown of all vaccines & efficacy against various strains. Have mainly focused on Original Strain & Predominant Delta Strain of SARS-CoV-2 for analysis and avoided Alpha or Beta Variant for analysis. Studies referenced in the thread for people to refer & read.

Now which vaccine is best ?

Answer is whichever you can get first.

Coz ⬇️

Delta is the new pandemic problem"
By editorial board @washingtonpost
"The threat of delta should prompt vaccine doubters to rethink"
"Do you want to meet delta in a dark alley? If not, get a shot.

All vaccines available in India offer you some protection against Delta Variant there could be some debate on % for academic scientific purposes. But please do get yourself vaccinated & dont wait to offer yourself as a bait to Delta Variant in trying to be brand conscious.

@threadreaderapp unroll