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. 2022 Jun 17;10(6):970.
doi: 10.3390/vaccines10060970.

Effectiveness of the ChAdOx1 nCoV-19 Coronavirus Vaccine (CovishieldTM) in Preventing SARS-CoV2 Infection, Chennai, Tamil Nadu, India, 2021

Sharan Murali  1 , Manikandanesan Sakthivel  1 , Kamaraj Pattabi  1 , Vettrichelvan Venkatasamy  1 , Jeromie Wesley Vivian Thangaraj  1 , Anita Shete  2 , Alby John Varghese  3 , Jaganathan Arjun  3 , Chethrapilly Purushothaman Girish Kumar  1 , Pragya D Yadav  2 , Rima Sahay  2 , Triparna Majumdar  2 , Manisha Dudhmal  2 , Azhagendran Sivalingam  1 , Sudha Rani Dhanapal  1 , Augustine Durai Samy  1 , Vijayaprabha Radhakrishnan  1 , Murali Mohan Muni Krishnaiah  1 , Suresh Arunachalam  1 , Punita Muni Krishna Gandhi  1 , Elavarasu Govindasamy  1 , Prabhakaran Chinnappan  1 , Dhana Priya Vadhani Sekar  1 , Prakash Marappan  1 , Ezhil Pounraj  1 , Parasuraman Ganeshkumar  1 , Murugesan Jagadeesan  3 , Manish Narnaware  3 , Gagandeep Singh Bedi  3 , Prabhdeep Kaur  1 , Manoj Murhekar  1
Affiliations

Effectiveness of the ChAdOx1 nCoV-19 Coronavirus Vaccine (CovishieldTM) in Preventing SARS-CoV2 Infection, Chennai, Tamil Nadu, India, 2021

Sharan Murali et al. Vaccines (Basel). .

Abstract

We estimated the effectiveness of two doses of the ChAdOx1 nCoV-19 (Covishield) vaccine against any COVID-19 infection among individuals ≥45 years in Chennai, Tamil Nadu, India. A community-based cohort study was conducted from May to September 2021 in a selected geographic area in Chennai. The estimated sample size was 10,232. We enrolled 69,435 individuals, of which 21,793 were above 45 years. Two-dose coverage of Covishield in the 18+ and 45+ age group was 18% and 31%, respectively. Genomic analysis of 74 out of the 90 aliquots collected from the 303 COVID-19-positive individuals in the 45+ age group showed delta variants and their sub-lineages. The vaccine's effectiveness against COVID-19 disease in the ≥45 age group was 61.3% (95% CI: 43.6-73.4) at least 2 weeks after receiving the second dose of Covishield. We demonstrated the effectiveness of two doses of the ChAdOx1 vaccine against the delta variant in the general population of Chennai. We recommend similar future studies considering emerging variants and newer vaccines. Two-dose vaccine coverage could be ensured to protect against COVID-19 infection.

Keywords: AZD 1222; COVID-19 vaccines; ChAdOx1 nCoV-19; Covishield; SARS-CoV-2 inactivated vaccines; vaccine effectiveness.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Vaccine coverage among the eligible population (18+) and the total number of reported COVID-19 cases by week, Chennai, Tamil Nadu, India, January–December 2021.
Figure 2
Figure 2
Participant enrollment, events, and data exclusions for estimating the effectiveness of ChAdOx1 nCoV-19 coronavirus vaccine (CovishieldTM) in reducing the delta variant of SARS-CoV2 infection, Chennai, Tamil Nadu, India, 2021.
Figure 3
Figure 3
Neighbor joining tree of the SARS-CoV-2 sequences retrieved from the clinical samples collected from the 45+ age group individuals who were positive for SARS-CoV-2 in the COVID-19 vaccine effectiveness study, Chennai, India, 2021. We generated the tree using MEGA version 10 with the Tamura-3-parameter model with a gamma distribution as the rate parameter and bootstrap replication of 1000 cycles. The colored text represents the lineages. We visualized the generated tree using FigTree v1.4.4.
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