Durability of ChAdOx1 nCoV-19 (Covishield^®) Vaccine Induced Antibody Response in Health Care Workers

Abstract

(i) Background: ChAdOx1 nCoV-19 (Covishield®) vaccine is widely used in India. We studied the Covishield® induced antibody response and its durability among health care workers (HCWs) (ii) Method: HCWs received two doses (0.5 mL) four weeks apart. Blood specimens, collected before each dose, day (D)60, D150 and D270 after second dose, were tested for anti-spike antibody (ASAb) titre and neutralising antibody (%) (NAb) using Elecsys Anti-SARS-CoV-2 S (Roche) and SARS-CoV-2 NAb ELISA Kit (Invitrogen), respectively. Data are expressed as proportions and median (interquartile range) and compared using non-parametric (iii) Result: Among 135 HCWs (83 males; age 45 (37–53); 36 had pre-existing ASAb), 29 (21.5%) acquired COVID-19 after 60 (39–68) days of vaccination. ASAb titre before second dose and at D60, D150, D270 were 77.2 (19.4–329.4), 512 (114.5–9212), 149 (51.6–2283) and 2079 (433.9–8644) U/mL, respectively. Compared to those without pre-existing ASAb, titres were significantly higher before second dose (5929 vs. 41, p p = 0.007) and D150 (1805 vs. 103, p p p = 0.362) but significantly higher at D60 (14,019 vs. 317, p p = 0.002) in the former group, though NAb percentage were higher at D60 (87 vs. 27, p p = 0.007) only (iv) Conclusions: Covishield® induces a higher antibody titre in those with pre-existing ASAb. The vaccine induced antibody starts falling 5 months after vaccination.

Keywords

• COVID-19
• coronavirus
• Covishield
• COVID vaccine
• Anti-SARS-CoV-2 antibody
• neutralising antibody