Blood samples were collected from 119 HCWs twenty-one days after first dose and from 99 HCWs twenty-one days after second dose (57 HCWs were common in both doses) of ChAdOx1, nCoV-19 vaccine for anti-SARS-CoV-2 antibody testing. vaccination showed a significant drop in antibody titre, while 56% of them didn’t show a detectable level of IgG, suggesting the need for a booster dose. Around 21% of the vaccinated HCWs with significantly low antibody titre were infected with the SARS-CoV-2, but a majority of Boc-NH-C6-amido-C4-acid them showed mild symptoms and recovered Boc-NH-C6-amido-C4-acid in home isolation without any O2 support. We noticed the effectiveness of the ChAdOx1 nCoV-19 vaccine as evident from the low rate of breakthrough infection with any severe symptoms. at room temperature. Serological analysis of IgG and total antibody (IgG, IgM and IgA) were performed using enhanced chemiluminescence technology by VitrosECiQ (Ortho Clinical Diagnostics, New Jersey, US) . Neutralising antibody sandwich ELISA To find out whether the seropositive patients were also developing the neutralising antibody, a neutralising antibody sandwich ELISA (GenScript, USA) following manufacturer’s protocol was also performed . Dynamics of IgG antibody over time Among 313 HCWs, 104 were RT-PCR confirmed COVID-19 patients. To evaluate the dynamics of the antibody titre, all RT-PCR confirmed COVID-19 HCWs were followed up at 2 months interval for 6 months of their first antibody measurement. Seroreactivity after vaccination 313 HCWs, who received ChAdOx1, nCoV-19 corona virus vaccine (COVISHIELD) , were included in the study. Blood samples were collected from 119 HCWs twenty-one days after first dose and from 99 HCWs twenty-one days after second dose (57 HCWs were common in both doses) of ChAdOx1, nCoV-19 vaccine for anti-SARS-CoV-2 antibody testing. Among these vaccinated individuals, we followed up 153 HCWs until December 2021 for breakthrough infection after first or second dose of vaccination. Statistical analyses Descriptive as well as inferential analyses were performed using R Software . A significance level of valueneutralisation Boc-NH-C6-amido-C4-acid activity against B.1.1.7 (double mutant strain) em vs /em . a canonical non-B.1.1.7 strain . This observation along with the enhanced antibody generation supports the immense potential of ChAdOx-1 nCov-19 vaccine. On the other hand, in a very recent report UK Health Security Agency (UKHSA) stated that a third booster of COVISHIELD vaccine provides 70% to 75% protection against symptomatic infection from B.1.1.529 variant (Omicron) . To conclude, our study, which dealt with the anti-SARS-CoV-2 antibody dynamics starting from prevalence through follow-up up to the 6 to 8 8 months of second dose of vaccination and its association on several Rabbit Polyclonal to RFA2 significant factors, may help to build better preventive strategies in future. Similar comprehensive study over the general population following Boc-NH-C6-amido-C4-acid vaccination will be necessary to monitor the trend and optimal resource utilisation for better management of the ongoing pandemic in a large country like India. Acknowledgements Authors would like to acknowledge Dr Krishanu Maulik, Indian Statistical Institute, Kolkata for critical evaluation of the manuscript. Ethical standards The study was approved by the Institutional Ethics Committee, NRS Medical College & Hospital. Data availability statement Most Boc-NH-C6-amido-C4-acid of the data used here are presented in the manuscript. Other data supporting the results reported in this study will be available from the first author, Dr Soma Sarkar (moc.liamg@rakrassdrd) upon request after taking into consideration of ethical issues. Conflict of interest Authors declare no competing interest..