CME INDIA Presentation by Admin.
Original Indian Study (Peer reviewed – Published online on 5th February 2022)
It gives a very illuminating learning that despite a higher antibody titre with Covishield, decline was significant at 6-months vs. no decline with Covaxin. It is worth to note that T2DM cohorts had lowest seropositivity, while hypertensive had significant antibody decline at 6-months.
The Study Title
“Humoral Antibody Kinetics with ChAdOx1-nCOV (CovishieldTM) and BBV-152 (CovaxinTM) Vaccine among Indian Healthcare workers: A 6-month Longitudinal Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) Study.”

What is this Study?
- The 6-month longitudinal study of humoral Ab kinetics following 2 doses of Covishield and Covaxin
Principal Investigators

- Dr. Awadhesh Kumar Singh, MD, DM (Kolkata);
- Dr. Sanjeev Ratnakar Phatak, MD (Ahmedabad);
- Dr. Nagendra Kumar Singh (N. K. Singh), Dhanbad;
- Dr. Arvind Gupta, MD, (Jaipur);
- Dr. Arvind Sharma, MD (Jaipur);
- Dr. Kingshuk Bhattacharjee, PhD (Kolkata);
- Dr. Ritu Singh, MD (Kolkata);

PAN INDIA Study (22 cities)

Drs. – Akash Kumar Singh (Vadodara), Amit Gupta (Noida), Anuj Maheshwari (Lucknow), Arvind Kumar Ojha (Kolkata), Bhavtharini (Erode), B. Harish Kumar (Mysore), J K Sharma (New Delhi), Jayant Panda (Cuttack), Kavya Chand Yalamudi (Guntur), Kiran Shah (Vadodara), M Gowri Sankar (Coimbatore), Manohar KN (Bangalore), Meena Chhabra (New Delhi), Pratap Jethwani (Rajkot), M Shunmugavelu (Trichy), Rajiv Kovil (Mumbai), Sunil Gupta (Nagpur), Subhash Kumar (Patna), Somnath (Hyderabad) and Urman Dhruv (Ahmedabad) are involved in this study as regional co-ordinators.
Authors are thankful to: Ms. Roma Dave (Dietician) and Dr. Priya Phatak (Ahmedabad), Dr. Bhavini Shah, Dr. Sandip Shah, and Dr. Krutarth Shah from Neuberg Supratech Laboratory, Ahmedabad.
What was done in the study?
- The first part (short-term) of this study has been published in Vaccine journal.
- Pan Indian researchers conducted a 6-month longitudinal study in vaccinated healthcare workers by serially measuring quantitative anti-spike antibody at 3-weeks, 3-months and 6- months after the completion of second dose.
- Geometric mean titre (GMT) and linear mixed models were used to assess the dynamics of antibody levels at 6 months.
- Authors now report the results from our 6-month longitudinal study that assessed the humoral antibody response after two doses of two vaccines administered in India.
- This cross-sectional Pan-India study has analysed humoral antibody dynamics in three groups of participants simultaneously which include:
- People who had past history of Covid-19 before the first dose of vaccine,
- People who developed breakthrough infection ≥2-weeks after the second dose and,
- People who remained infection naïve for entire 6-month after the completion of second dose.
- The study has also analysed the humoral response between Covishield and Covaxin over 6-month.
- The study was done on 481 health care workers.
- These HCWs showed a significant decrease in the anti-spike antibody at 6-months.
- Reduction in antibody was regardless of demographics, comorbidities and the vaccine type.
- T2DM cohorts had lowest seropositivity, while hypertensive had significant antibody decline at 6-month.
Quick Take-away
Of the 481 participants, all 360 infection-naive people showed a significant decrease in anti-spike antibody at 6-months. |
Reduction in antibody was regardless of demographics, comorbidities and the vaccine type, in a 6-month linear mixed model. |
Despite a higher antibody titre with Covishield, decline was significant at 6-month vs. no decline with Covaxin. |
T2DM cohorts had lowest seropositivity, while hypertensive had significant antibody decline at 6-months. |
Recipients of Covishield had higher anti-spike antibody titers than recipients of Covaxin, however significant decline in antibody titers was seen with Covishield and not Covaxin. |
Individuals with past or breakthrough COVID infection had the highest antibody titers which showed minimum decline at 6 months. |
Few notable findings:
- Waning of antibody titre over time regardless of age, sex, BMI, comorbidities and type of vaccine but it was significantly low in hypertensives.
- Past h/o COVID-19 had significantly higher titre at all time points compared to naive individuals after 2 doses.

- Second dose of Vaccine did only a little increase in titre vs. 1st.
- Covishield arm had significant higher Ab titre at all time points vs. Covaxin after 2-doses.
- 44% decline in titre at 6-mth compared to peak with Covishield vs. minimal/no reduction (8%) in Covaxin.

- 5.6-fold reduction in sero+ to anti-spike Ab at 6-month in naive cohorts regardless of the vaccine received.
- Sero+ was significant higher with Covaxin vs. Covishield at 6-mth in SARS-CoV-2 naive, though no significant difference noted in propensity-matched cohorts.
- No difference in breakthrough infection rate was noted between Covishield and Covaxin recipients at 6-month.
CME INDIA Learning Points
(By Dr. Awadhesh Kumar Singh)
- Waning of anti-spike antibody titre over time occurs regardless of age, sex, BMI, comorbidities and type of vaccine
- Antibody titre wanes significantly low in hypertensive cohort vs. normotensive at 6-month,
- People with past history of COVID-19 have significantly higher anti-spike antibody titer at all time points compared to SARS-CoV-2 naive individuals after two doses of either vaccine,
- Notably second dose of vaccine brings only a little augmentation of spike antibody titre compared to the first dose.
- Covishield recipients had significantly higher anti-spike antibody titer at all time points until 6- month after two doses.
- In this study, there was a 56% decline in anti-spike antibody GMT at 6-months compared to the peak period (21-days after second dose) in SARS-CoV-2 naive individuals.
- There was a 44% decline in anti-spike antibody GMT at 6-months compared to peak period (at 21-days) after the second dose of Covishield.
- There was minimal-to-no reduction (8% decline) in anti-spike antibody GMT at 6-months compared to peak period (at 21-days) after the second dose of Covaxin and similar findings were noted in propensity-matched cohorts.
- There was 5.6- fold reduction in seropositivity to anti-spike antibody at 6-month in SARS-CoV-2 naive cohorts regardless of the vaccine received.
- Despite a significant decline in seropositivity with both vaccines, seropositivity was significantly higher with Covaxin compared to Covishield at 6-month in SARS-CoV-2 naive cohorts, although no significant difference was noted in propensity-matched cohorts.
- No significant difference in breakthrough infection rate was noted between Covishield and Covaxin recipients at 6-month.
CME INDIA Tail Piece



References:
- Awadhesh Kumar Singh, Sanjeev Ratnakar Phatak, Ritu Singh, Kingshuk Bhattacharjee, Nagendra Kumar Singh, Arvind Gupta, Arvind Sharma,Humoral antibody kinetics with ChAdOx1-nCOV (Covishield™) and BBV-152 (Covaxin™) vaccine among Indian Healthcare workers: A 6-month longitudinal cross-sectional Coronavirus Vaccine-induced antibody titre (COVAT) study,Diabetes & Metabolic Syndrome: Clinical Research & Reviews,2022,102424,ISSN 1871-4021,https://doi.org/10.1016/j.dsx.2022.102424.(https://www.sciencedirect.com/science/article/pii/S18714 02122000388)
- Awadhesh Kumar Singh, Sanjeev Ratnakar Phatak, Ritu Singh, Kingshuk Bhattacharjee, Nagendra Kumar Singh, Arvind Gupta, Arvind Sharma, Title: Antibody Response after First and Second-dose of ChAdOx1-nCOV (Covishield) and BBV-152 (Covaxin) among Health Care Workers in India: The Final Results of Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) study, Vaccine, 2021, , ISSN 0264-410X, https://doi.org/10.1016/j.vaccine.2021.09.055
- Humoral Antibody Kinetics with ChAdOx1-nCOV (CovishieldTM) and BBV-152 (CovaxinTM) Vaccine among Indian Healthcare workers: A 6-month Longitudinal Cross-sectional Coronavirus Vaccine-induced Antibody Titre (COVAT) Study AWADHESH KUMAR SINGH, Sanjeev Ratnakar Phatak, Ritu Singh, Kingshuk Bhattacharjee, Nagendra Kumar Singh, Arvind Gupta, Arvind Sharma medRxiv 2022.02.03.22270182; doi: https://doi.org/10.1101/2022.02.03.22270182
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