How effective is Made in India Covaxin?

• Why is the recommended gap between two COVAXIN doses is 28days?

• Effectiveness of India’s indigenously developed COVID19 vaccine Covaxin

• Effectiveness of 1st dose of covaxin

• Effectiveness of two dose of covaxin

• Whether one dose of covaxin dose is enough?

• How long two covaxin doses effective, long term effectiveness of covaxin

• Side effects of Covaxin

Introduction

• COVAXIN, India’s Indegenious COVID19 vaccine, researched and developed by Bharat Biotech International Limited in association with Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV).

• Covaxin is a whole-virion inactivated SARS-CoV-2 vaccine. Recommended temperature required for the storage of Covaxin is 2-8°C. 

• Covaxin, BBV152 are synonyms of the same vaccine. 

• Preliminary results of immunogenicity and safety analysis for the of India’s Indigenously developed COVID19 vaccine COVAXIN was recently published in renowned medical journal The lancet [1][2].

COVAXIN [3]

COVAXIN [3]

Experimental

• Detailed results of Phase 1 and 2 trial run are published. Similar results of phase 3 are yet to be published.

• In phase 1 clinical trial, test conducted on 375 people aged 23–62 years. Total 11 hospitals participated in the phase 1 study. Test duration: 13-30.July.2020.

• In phase 2 clinical trial, test conducted on 380 people aged 12–18 years and 55–65 years. Trial run was conducted during 05-12.Sep.2020.

• Both the trials were conducted on COVID19 negative participants (Both RTPCR and ELISA negative). 

• They were randomly administered either the 3 μg or the 6 μg vaccine in 0.5 mL. 

• Total 11 hospitals across India took part in the Phase 1 & 2 study.  

• Hospitals took part in both phase 1&2

   Nizam’s Institute of Medical Science, Hyderabad, Telangana, 

  AIIMS, New Delhi, AIIMS, Patna, Bihar

  PGIMS, Rohtak, Haryana, Redkar Hospital & Research Centre, Goa, 

  Jeevan Rekha Hospital, Belgaum, Karnataka, 

  Gillukar Multispeciality Hospital, Nagpur, MH

  Prakhar Hospital, Kanpur, UP

  SRM Medical College Hospital & Research Centre, Chennai, TN. 

  Hospitals took part in Phase 1 alone

  Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha

  Rana Hospital and Trauma Centre, Gorakhpur, UP

• Clinical tests were done with wild type SARS-CoV-2 i.e. with coronavirus with no

major mutations.

Result

• Antibody gets developed to safeguard the body against the attack of the external antigen (virus). Antibody basically develops immunity in our body. 

• Corona virus neutralising antibodies conc, Immune response, Immunity, Seroconversion etc were measured by Micro Neutralization Test (MNT50). It measures antibody concentrations in blood samples. 

• MNT50 quantifies the amount of virus required to kill 50% of infected hosts i.e. antibody[4] [5]. 

• Seroconversion rates (SCR) were defined by the concentration of virus neutralising antibody concentration achieving atleast 4 times above baseline. We can express it in this way also that a participant who has achieved seroconversion is defined as having a postvaccination antibody concentration at least four times higher than their respective prevaccination value. 

• Seroconversion i.e. the presence of antibodies can offer immunity from reinfection, but the immunity may or may not be permanent.

Conclusion

• Only one dose (1st) of the covaxin is very less effective than the two doses combined. 

• After the 1st dose Immune response is around 21% only. 

• A large increase in immune response is observed after the 2nd dose. 

• Gap between two doses plays an important role. Gap of 28 days is more effective than 14 days. In case of 28d gap, Immune response jumps to 96.6% and continues to be the same upto 56 days. In case of 14d gap, Immune response jumps to 91.92% but a mild decrease is observed afterwards upto 104days. This is the reason the recommended gap between two covaxin doses is 28d. 

• Further increase in gap (more than 28d) may result in an increase in immune response but the person shall be more vulnerable to COVID infection as the immune response of COVAXIN less after 1st injection. 

• The 6 μg with formulation has been selected for the phase 3 efficacy trial. Hence in this article data corresponding to 6μg formulation is only used for plotting the data. 

• Long term COVAXIN effectiveness measured upto 104d only but for 6 and 12 months is in progress. 

• In phase 2 trial no life-threatening events were observed. The most common side effects are pain at the injection site, headache, fatigue, and fever. 

• The phase 1 and 2 trial proves that COVAXIN is safe, does not produce any life threatening side effects, and generates corona virus neutralising antibodies. Phase 3 trial is necessary to understand the % efficacy or %effectiveness. 

• The interim clinical efficacy data of COVAXIN is reported as 81% obtained after a phase 3 clinical trial on 25,800 participants between the age group of 18-98 years [6]. Detailed data in a peer reviewed journal is awaited .

Reference and footnote

[1] Ella, Raches, et al. "Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152:

a double-blind, randomised, phase 1 trial." The Lancet Infectious Diseases 21(5) (2021): 637-646.

Published: January 21, 2021 DOI:https://doi.org/10.1016/S1473-3099(20)30942-7,

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30942-7/fulltext

[2] Ella, Raches, et al. "Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152:

interim results from a double-blind, randomised, multicentre, phase 2 trial, and 3-month follow-up

of a double-blind, randomised phase 1 trial." The Lancet Infectious Diseases, 21(7), (2021) 950-961,

Published: March 08, 2021 DOI:https://doi.org/10.1016/S1473-3099(21)00070-0,

https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00070-0/fulltext

[3] https://www.bharatbiotech.com

[4] Virus quantification https://en.wikipedia.org/wiki/Virus_quantification, accessed on 27.Jun.2021]

[5] Flint, S. J. (2009). Principles of Virology. United Kingdom: ASM Press.

https://www.wiley.com/en-vu/Principles+of+Virology,+3rd+Edition,+2+Volume+Set-p-9781555814434

[6] Bharat Biotech Announces Phase 3 Results of COVAXIN®:

India’s First COVID-19 Vaccine Demonstrates Interim Clinical Efficacy of 81%, Hyderabad, India,

03, March, 2021, https://www.bharatbiotech.com/images/press/covaxin-phase3-efficacy-results.pdf



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