The current study aimed to estimate the seroprevalence of SARS-CoV-2 IgG (S-protein) antibodies along with neutralizing assay (RBD-domain) among the whole blood donors without any prior Covid-19 history or symptoms visiting Blood Centre at a Tertiary care institution, South India amidst the ongoing pandemic. During September 2020 to March 2021, 1034 whole blood donors were enrolled into the study and were screened for anti-SARS-CoV-2 IgG antibodies using Chemiluminescence assay followed by neutralizing antibodies using surrogate neutralization ELISA. The study reported seroprevalence of 49.4%, (95% CI 46.3–52.5) among whole blood donors, with test sensitivity and specificity adjusted prevalence of 54.9% (95% CI 51.5–58.3). Seroprevalence was similar across age groups, gender, voluntary/replacement donations, area of residence, ABO and Rh groups without any statistical significance. However higher IgG antibody responses were found to be elicited in the 30–45 years age group when compared with 18–29 years age group ( p value 0.046). This study also analysed the mean neutralizing capacity of SARS-CoV-2 antibodies among 97 blood donors which was 71.9 (SD: + 21.03, range 15.5 to 97.3). Donor samples with SARS-CoV-2 IgG S/Co > 9.5 had significantly higher neutralising capacity (> 68%) when compared with donor samples of S/Co < 9.5 ( p value 0.000). Real-time seroprevalence studies will help to know the herd immunityamong the blood donors which will assist in knowing the Covid-19 transmission dynamics, distribution of immunity levels at a particular point in time, immunity gaps, development of novel therapeutics and prioritize the vaccination programmes to high risk individuals.

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Introduction The SARS-CoV-2 illness (COVID-19) has spread around the world, primarily through person-to-person transmission, and is a serious public health concern. Based on the severity of illness symptoms, SARS-CoV-2 infection can be classified as either apparent or occult. To date, real-time reverse transcription polymerase chain reaction (RT-PCR) on respiratory specimens, particularly nasopharyngeal and oropharyngeal swabs, or nasopharyngeal wash or aspirate, has been the gold standard for the identification of COVID-19. A negative RT-PCR does not necessarily rule out SARS-CoV-2 infection. Occult COVID-19 infections could least be identified with RT-PCR. Aims and objectives To assess the prevalence of possible occult COVID-19 infection in healthcare personnel by RT-PCR and serology testing for SARS-CoV-2 virus. Methods A cross-sectional study was conducted on health care workers at a tertiary care hospital in South India during the period from October 2020 to January 2021. None of the study participants were vaccinated against COVID-19 during the study period. Nasopharyngeal swabs collected for RT-PCR were tested using Cobas 480 platform (Roche, Basel, Switzerland). Peripheral blood venous sampling was performed to collect EDTA (ethylenediaminetetraacetic acid) and plain samples. SARS-CoV-2 IgG antibodies against spike proteins were estimated using ECI Vitros platform (Ortho Clinical Diagnostics, Raritan, USA). Results The mean age of study participants was 34.78 years (SD±9.51) with an age range of 19-69 years. The study participants were stratified into age groups of 19-25 years, 26-40 years, 41-60 years, and above 60 years, gender, ABO and Rh blood groups, and occupational and further based on their area of work as Covid and Non-Covid for the purpose of statistical analysis. Total 190 samples from healthcare workers (HCWs) were tested for RT-PCR using nasopharyngeal swabs collected at the time of enrolment into the study, and all the 190 samples tested negative for RT-PCR. Among 190 HCW samples screened for SARS-CoV-2-IgG antibodies, 48 (25.3%) were found reactive for IgG antibodies while 142 (74.7%) were found non-reactive. Conclusion Our study findings suggested that using RT-PCR testing, which may only identify those with a prolonged viral shedding period and minimum viral loads, the proportion of asymptomatic/occult infections could be underestimated.

Background: COVID-19 is an emerging and rapidly evolving situation globally, and it poses additional burden for emergency health care services especially the transfusion medicine and the need of an hour to safeguard our regular blood donors. Aim and Objectives: The study aims to find out the proportion of COVID-19 infection among blood donors and non-blood donors (NBDs) and to assess their behavioral risk factors that predispose to COVID-19. Materials and Methods: A case-control study was conducted among regular blood donors and non-blood donors at the department of transfusion medicine attached to tertiary care hospital with an objective to find out the proportion of COVID-19 status and the risk factors associated with its occurrence. Results: Total of 834 participants involved in our study. Accordingly, we found the proportion of COVID-19 to be 9% among regular blood donors and 2% among NBDs. A significant association was noted with regular going out, co-morbidities, B positive blood group and perceived stress as the risk factors in regular blood donors. Moreover, among NBDs maintaining social distancing and regular washing of hands/use of sanitizers were significant factors. Conclusions: The novelty of this study helps to remake our policies concerned mainly on the protection of our potentially emergency service providers against COVID-19 infection.

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