SARS-CoV-2 IgG Surveillance in Asymptomatic Blood Donors and Health Workers

Background and Objectives. SARS-CoV-2 virus has caused a global pandemic as declared by the World Health Organisation (WHO) in March 2020. In India, the first case was reported in Kerala on the 30th of January, and since then, many states are active but some are showing flattening. Following the seroprevalence testing in healthy blood donors, we can monitor the spread of the virus among healthy people, thus eventually leading to implementing strategies to reduce the spread. Thus, a need was felt to conduct a study to assess the IgG antibody status in healthcare workers differentiating those who were in COVID-19 and others in non-COVID-19 emergency duties during this pandemic. Materials and Methods. 2085 blood donors were allowed to donate blood only after fulfilling all the criteria laid down by the FDA of India with additional history of excluding COVID-19 suspects. IgG antibody testing was performed by chemiluminescence, and results were noted along with their reactive status. Their reactive status was analyzed with donor information to get an idea of the risk parameters for COVID-19. Medical healthcare workers in whom the study was carried out were 560, out of which 114 had worked in COVID-19 duties and 446 had worked in non-COVID-19 emergencies areas. COVID-19 area duties were further subdivided into triage, holding area, isolation, and COVID-19-related duties. The samples were run on architect i2000 and evaluated for their plasma immunoglobulin G. Results. Amongst the asymptomatic blood donors, 1.9% was found to be COVID-19 IgG antibody positive. It was observed that maximum COVID-19 IgG positivity (57.1%) was seen in the age group 18–29 years followed by 26.2% in the age group 30–39 years. Donors in the age group 40–49 years showed antibody positivity of 16.7%, and no antibody-positive donors were found above 50 years of age. COVID-19 IgG positivity was maximum in replacement donors (61.9%) followed by family donors (28.6%) and least involuntary donors (0.6%) Blood donors who showed high IgG positivity were mainly of labor class. Antibody IgG testing on medical healthcare workers showed 2.3% positivity. The healthcare workers who were posted in COVID-19 duties showed 4.8% positivity in the holding area (waiting area with the treatment of patients till their RT PCR report comes) and 5.7% in other COVID-19 areas related to laboratory work. Healthcare workers doing duties in COVID-19 areas showed 2.7% positivity, while those doing duties in non-COVID-19 emergency areas showed a positivity of 2.2%. Conclusion. Our study shows that the prevalence of detectable antibodies was low in the general population in India and many patients were asymptomatic as seen in the blood donors, especially the labor class. Maximum exposure was present in young healthy males of labor class who remained asymptomatic. The healthcare workers were more exposed to COVID-19 as compared to the general population probably due to lack of precaution and awareness. Those doing non-COVID-19 duties were also exposed appreciably and needed to take all the precautions required for COVID-19 duties.

1. Background and Objectives
SARS-CoV-2 virus has caused a global pandemic as declared by the WHO in March 2020. In India, the first case was reported in Kerala on the 30th of January, and since then, many states are active but some are showing flattening [1].

Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) is being considered as the gold standard technique that confirms the presence of COVID-19 [2]. However, testing of specimens from multiple sites may improve the sensitivity and reduce false-negative test results [3]. Due to the high infectivity rate and a majority of patients being asymptomatic, widespread serological screening was required. Memory antibody (IgG type) assessment is useful as many healthy individuals in the epidemic area may be asymptomatic but infected and possess a threat for further spread of the virus. Monitoring IgG will in turn help us for guiding future decisions on the right time to relax social distancing measures and minimize possible epidemic outbreaks [4]. The role of SARS-CoV-2 IgG antibodies, verified by PCR, has shown positive results for confirming the infection [5]. Both SARS-CoV and MERS-CoV infections were believed to originate in bats, and these were transmitted directly to humans [6]. Following the seroprevalence testing in healthy blood donors, we can monitor the spread of the virus among healthy people and, thus, will eventually lead to implementing strategies to reduce the spread. Evidence is also emerging that monocyte/macrophage dysfunction may be central to the immunopathology [7] and that the functional characteristics of antibodies to SARS‐CoV‐2 spike protein (SP) might be a determinant of disease outcome. Antibody response against enveloped viruses such as SARS‐CoV‐2 comprises immunoglobulin (Ig) M, IgG3, IgG1, and IgA antibodies to glycoproteins of the virus envelope and nucleoproteins (NP, internal to the envelope). IgG (IgG3 and IgG1) antibodies against virus envelope glycoproteins have many functional characteristics that make up the most efficacious antibody response against viruses, as illustrated by human immunodeficiency virus- (HIV-) 1 infection [8]. Healthcare workers are the frontline workforces who provide care to both suspected as well as confirmed COVID-19 cases. Thus, they are at a higher risk of acquiring the disease, and if they are infected, they possess a serious risk for vulnerable patients as well as fellow healthcare workers. Thus, a need was felt to conduct a study to assess the IgG antibody status in healthcare workers differentiating those who were in COVID-19 and others in non-COVID-19 emergency duties during this pandemic. Antibodies in healthcare workers will help in maximizing our safe manpower resources and avoid unnecessary quarantine. Comparison with the general population which was represented by asymptomatic blood donors was carried out to assess the prevalence of antibodies in the population. The objective of the study was that, during the time of pandemics and panic amongst the general population and the government, we should be able to provide data regarding the safety measures of our medical staff and the development of antibodies in the population. A material and method setting study was carried out by the Department of Transfusion Medicine, King George’s Medical University, Lucknow, in June 2020.It was carried out in 2121 asymptomatic blood donors and 560 medical healthcare workers working in COVID-19 and also non-COVID-19 emergency duties. The work was a part of university policy, and in order to screen its healthcare workers and blood donors for COVID-19 antibodies, adequate precautions and decisions could be taken accordingly. The department of transfusion medicine has one of the biggest blood banks in the country and caters to donors all over the state of Uttar Pradesh and, thus, represents a huge proportion of the asymptomatic population of the state of Northern India. King George’s Medical University is the largest medical university in the country and is giving both COVID-19 and non-COVID-19 care to the patients. Sample collection: blood donors were allowed to donate blood only after fulfilling all the criteria laid down by the FDA of India with additional history of excluding COVID-19 suspects. This included contact history with any COVID-19-positive patient, recent travel history, and symptoms of COVID-19. Consent was taken regarding the screening of COVID-19 antibodies. They donated blood only after completing their fitness. In the blood units, apart from regular screening of HIV, hepatitis B, hepatitis C, malaria, and syphilis, testing for IgG antibodies for COVID-19 was also performed. It was carried out on 2 ml EDTA blood from which plasma was used after centrifugation and IgG antibodies testing was performed by chemiluminescence technology by SARS-CoV-2 IgG assay (Abbott Laboratories Inc. CLIA) on the Abbott ARCHITECT i system. The results of IgG antibodies (OD Values) were noted along with their reactive status. Their reactive status was analyzed with donor information to get an idea of the risk parameters for COVID-19. Medical healthcare workers in whom the study was carried out were 560. They included doctors, technicians, staff nurses, attendants, sweepers, and clerks and were randomly selected. Out of them, 114 had worked in COVID-19 duties and 446 had worked in non-COVID-19 emergencies areas. COVID-19 area duties were further subdivided into triage, holding area, isolation, and COVID-19-related duties. Healthcare workers working in different departments were screened to analyze the high-risk areas for COVID-19. 2 ml blood was collected from all the healthcare workers in EDTA vials. Blood was collected from healthcare workers from COVID-19 areas only after 14 days of quarantine which was the standing government policy. Non-COVID-19 workers were not quarantined; hence, blood was collected when they were on duty. The collection was carried out according to the guidelines of the university for understanding the spread of COVID-19 in the university which can be used later for duty rostering purposes. The samples were run on architect i2000 and evaluated for their Immunoglobulin G status. 24 samples that tested positive for antibodies were retested on a rapid card test Q Line Rapid for COVID-19 IgG to confirm its sensitivity and specificity.