key: cord-0798587-2nzs07cc
authors: Kale, Pratibha; Patel, Niharika; Gupta, Ekta; Bajpai, Meenu
title: SARS-Coronavirus-2 seroprevalence in asymptomatic healthy blood donors: indicator of community spread
date: 2021-10-14
journal: Transfus Apher Sci
DOI: 10.1016/j.transci.2021.103293
sha: d8097ebda7c632546125e62746da73033bf06174
doc_id: 798587
cord_uid: 2nzs07cc

BACKGROUND: The Corona virus disease 2019 (COVID-19) pandemic caused by SARS -Corona virus-2 (SARS-CoV-2) has been a major concern the world over. Serological surveillance is an important tool to assess the spread of infection in the community. This study attempted to assess the prevalence of antibodies to SARS-CoV-2 among blood donors in Delhi, India during the pre-vaccination period. METHODS: Seroprevalence of SARS-CoV2-2 IgG antibodies were determined in blood donors reporting to the Department of Transfusion medicine at a tertiary care hepatobiliary center, in India from September to October 2020. The SARS-CoV-2 IgG antibodies against spike subunit 1 protein were measured using the enhanced chemiluminescence method. RESULTS: A total of 1066 blood donors were screened. The overall seropositivity for SARS-CoV-2 IgG antibodies was 27.57% (294/1066). The highest seropositivity was seen in the age group 26-35 years, 46.6% (137/492), followed by 18-25 years, 28.2% (83/260), 36-45 years, 19.4% (57/244), and more than 45 years, 5.8% (17/70). The seropositivity in the donors who had donated blood previously was 26.1% (189/723). There was no statistically significant difference amongst seroprevalence in the blood groups, AB blood group (32.6%, 95% CI 23.02-43.3), group B (27.2%, 95% CI 22.8-32.09%), group A (27.1%, 95% CI 21.8-32.9%), and group O (27.02%, 95% CI 22.3-32.1%) (p 0.539). CONCLUSIONS: There was significantly higher seropositivity for SARS-CoV-2 antibodies in the voluntary healthy blood donors indicating community spread and large number of asymptomatic cases in Delhi. Higher seroprevalence in younger adults indicated increased exposure to the virus and lack of COVID appropriate behaviour.

3 antibodies. The same is expected to reflect in the asymptomatic blood donors who have donated blood during this period. The screening of blood donors for SARS-CoV-2 is not mandatory as per the National Blood transfusion guidelines. [3] There is a rise in the total antibody specific to SARS-CoV-2, by the second week of infection in COVID-19 confirmed cases. The IgM antibodies tend to disappear soon while the IgG antibodies persist. [4] To study the seroprevalence of SARS-CoV-2 antibodies in asymptomatic voluntary blood donors in our institute, we conducted this study to evaluate the antibody levels in this group and compared it with the serological and symptomatic disease prevalence in Delhi during the same period.

The study was conducted in the department of Transfusion medicine at a tertiary care hepatobiliary center, in India in voluntary blood donors during the period of 24th September 2020 to 31st October 2020 after approval from the institute ethics committee. Serum samples from healthy eligible blood donors were collected after appropriate consent. The donor eligibility criteria were as per the Drug and Cosmetics Rules 1945 amended March 2020; any healthy adult 18-65 years of age, weighing more than 45 kg, with hemoglobin more than 12.5gm, with temperature, pulse, and blood pressure within normal limits as well as having no disease/risk factor which affected donor or recipient safety were eligible for the study. The blood donors who did not meet the eligibility criteria were deferred and thus excluded; additionally, those with documented prior SARS-CoV-2 infection and those who refused to give consent were excluded from the study. The routine blood donor screening tests including blood grouping and transfusion-transmitted infection screening were also done. The SARS-CoV-2 IgG antibodies were measured using the enhanced chemiluminescence method (Vitros Our study findings indicate a widespread asymptomatic infection in the community leading to high seropositivity in healthy voluntary blood donors. Thus, a large proportion of COVID-19 cases are asymptomatic leading to an antibody response that may contribute to herd immunity. This data is peculiar as the samples were just after the peak cases in Delhi in 2020.

( Figure 2 , Table 3 ). Previous studies during the early part of the pandemic may not be truly representative of the seroprevalence in healthy blood donors. The plasma from the blood donors having high titres could be used for plasma therapy in COVID-19. Our study also J o u r n a l P r e -p r o o f 8 shows similar seroprevalence in all blood groups. Thus we hypothesize that there could be no difference any blood for increased susceptibility to infection with SARS-CoV-2. With the beginning of vaccination for the general population, there will be seropositivity, so this study is important to study the seropositivity in the vaccine naïve population. As RNA testing for voluntary blood donors or a healthy asymptomatic population was not recommended, we do not have the data on the viral load in such population.

Conclusion: There was high seropositivity for SARS-CoV-2 antibodies in the voluntary healthy blood donors indicating community spread and a large number of asymptomatic cases in Delhi. The higher seroprevalence in younger adults indicated increased exposure to the virus and lack of COVID appropriate behaviour. This also reiterates the need to emphasize preventive measures like universal masking, hand hygiene, and social distancing to prevent the silent spread of infection.

Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. J o u r n a l P r e -p r o o f 

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Figure legends: Figure 1. Forest plot for Blood Groupwise SARS-CoV-2 seropositivity