Prospective sero surveillance among healthcare workers vaccinated with ChAdOx1 nCoV-19 Corona vaccine in a tertiary hospital of Kerala, India

ABSTRACT

BackgroundIndia started Covid-19 vaccination from January 16, 2021 after the approval of two candidate vaccines namely Covishield and Covaxin . We report antibody responses among healthcare workers following two doses of Covishield vaccination in a tertiary care setting. MethodsThis prospective serosurveillance study was done among healthcare workers of Jubilee Mission Medical College, vaccinated during January- March 2021. Blood samples were drawn from 170 participants after their 1st dose and from 156 participants after their 2nd dose of Covishield to measure the specific Ig G antibodies against the recombinant S1 subunit of the S protein of SARS-CoV-2. ResultsThe median level of anti SARS CoV-2 Ig G antibody 28 days after the first dose vaccination is 3.64 S/C (IQR=5.91) and 11.6 S/C (IQR= 5.97) after 14 days of second dose vaccination. Protective levels of anti SARS CoV-2 Ig G antibodies is developed by 25 participants (14.7%) after 28 days of first dose of vaccination and by 109 participants (69.9%) after 14 days of second dose. 18-44 years age group (p=0.027) and absence of comorbidities (p=0.079) are associated with protective IgG levels. ConclusionsRise in specific Ig G is observed after vaccination. Higher antibody response is observed with younger age group and absence of comorbidities, though statistically not significant. The influence of BMI is also not significant.