Study of immunogenicity, safety and efficacy of covishield vaccine among health care workers in a tertiary cardiac care centre.

Purpose: The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might be curtailed by vaccination. We assessed the safety, and immunogenicity of Covishield vaccine among Health care workers (HCWs) in a tertiary cardiac care centre.

Methods: It's a prospective analytical study, conducted at Sri Jayadeva Institute of cardiovascular science and research centre, Mysore, between January 2021 to May 2021. Pre and Post vaccination SARS CoV2 IgG antibodies were assessed among 122 HCWs. Interval between two doses in this study were 4 and 6 weeks. Adverse events following immunisation b(AEFI) and efficacy were assessed and followed up for two month post vaccination.

Results: Post vaccination seropositivity was 69.67% in overall study participants. Seropositivity and P/N ratio median value in uninfected and infected group were 60.43% (n ​= ​55),3.47 (IQR: 2.56-5.22) and 96.77% (n ​= ​30),9.49 (IQR: 7.57-12.30) respectively (P ​< ​0.001). Seropositivity and P/N ratio after 4 and 6 weeks were 48.3% (n ​= ​60), 2.95 (IQR: 1.91-4.24), and 83.8% (n ​= ​31), 4.88, (IQR: 3.39-6.43) respectively (P ​< ​0.001). AEFI after first and second dose was 72.9% and 27.8% (p ​< ​0.05) respectively. The most common symptoms after both doses of vaccination were local pain (73% & 88.2%), followed by fever (38.2% & 26.5%). The average duration of symptoms in both doses was 1.75 days. Of 122 participants only 10 (8.19%) had breakthrough infection after two doses of vaccination with mild severity.

Conclusion: Covishield vaccine has showed seropositivity of 69.67%.It has acceptable level of safety profile. Seropositivity and P/N ratio has increased with increase in interval between two doses. Though it has not prevented breakthrough infection it has certainly reduced the severity of infection.