Effectiveness of COVID-19 Vaccine (Covishield) among Health Care Workers of a Tertiary Cancer Care Hospital by Antibody Detection by Semi-Quantitative ELISA Method.

Introduction: Currently there is no recommendation for testing post vaccination COVID antibody levels, however with repeated COVID waves it is important to evaluate post vaccination COVID antibody levels specifically among Health Care Workers. Methods: This was an interventional study which was done with an objective of obtaining clinical history of COVID infection and vaccination status of the Health Care Worker (HCW) of the institute and to evaluate COVID 19 antibody levels by performing ELISA test. After taking consent, blood collection was done from 1399 health employees of The Gujarat Cancer & Research Institute. These samples were tested for post vaccination COVID antibody levels. The decrease in mean antibody levels among the partially and fully vaccinated groups was found to be significant by ANOVA at p value 0.05. Individuals with previous COVID infection history had better post COVID antibody levels after 6 months of last COVID dose and this was statistically significant by unpaired t test. Conclusion: In this study we concluded that post vaccination COVID antibody level decreases consistently with time and number of COVID vaccine doses have no differences over long standing COVID antibody levels. [ABSTRACT FROM AUTHOR]