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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 7  |  Issue : 2  |  Page : 186-189

Sero-prevalence of COVID-19 in blood donors of North India – Single-center report


1 Department of Transfusion Medicine, Medanta Institute of Education and Research, Medanta The Medicity, Gurgaon, Haryana, India
2 Medanta Institute of Education and Research, Medanta The Medicity, Gurgaon, Haryana, India

Date of Submission25-Jan-2022
Date of Decision06-Aug-2022
Date of Acceptance10-Aug-2022
Date of Web Publication5-Nov-2022

Correspondence Address:
Swati Pabbi
Department of Transfusion Medicine, Medanta Institute of Education and Research, Medanta The Medicity, Gurgaon, Haryana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/gjtm.gjtm_6_22

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  Abstract 


Background and Objectives: COVID-19 has infected and caused the deaths of millions of people globally with India being the second most affected country in the world. The primary objective of the study was to determine the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) antibodies in healthy blood donors in North India. The secondary objective of the study was to find the association of vaccination and infection with seropositivity in the blood donors. Methods: All blood donor samples were screened for the presence of IgG antibodies against SARS CoV2 spike (S1) protein. Anti-SARS CoV2 IgG antibody status, demographic data, history of past COVID infection, and vaccination of all eligible donors in the study period were collected. Seroprevalence was calculated as the percentage of total number of donors positive for anti-SARS CoV2 IgG antibodies. Month-wise seroprevalence was also calculated and analyzed. Results: Out of 1456 donors, 874 were found to be seropositive, resulting in a seroprevalence of 60%. Seroprevalence was found to be 38.3% and 77%, respectively, in the months of April and May 21. Seropositivity was 100%, 92%, 79%, and 54% in those with a history of both COVID infection and vaccination, vaccination only, infection only, and no history of vaccination or infection, respectively. Conclusion: Blood donors represent an easy access to seroprevalence studies and need to be tapped at the national level to obtain a temporal picture of the COVID-19 situation to guide healthcare policies, mark regions where vaccination drives need to be intensified.

Keywords: Anti-severe acute respiratory syndrome coronavirus 2 IgG, seropositivity, seroprevalence of COVID-19, vaccination drive


How to cite this article:
Tiwari AK, Pabbi S, Aggarwal G, Marik A, Sharma S, Singh M, Gupta S, Golia S. Sero-prevalence of COVID-19 in blood donors of North India – Single-center report. Glob J Transfus Med 2022;7:186-9

How to cite this URL:
Tiwari AK, Pabbi S, Aggarwal G, Marik A, Sharma S, Singh M, Gupta S, Golia S. Sero-prevalence of COVID-19 in blood donors of North India – Single-center report. Glob J Transfus Med [serial online] 2022 [cited 2022 Dec 8];7:186-9. Available from: https://www.gjtmonline.com/text.asp?2022/7/2/186/360493




  Introduction Top


COVID-19 has infected and caused the deaths of millions of people globally, with India being the second most affected country in the world.[1] With the ongoing pandemic and the vaccination drive all over the country, seroprevalence studies are vital. Seroprevalence studies would also play an important role in helping public health authorities assess the policies, determine healthcare capacity, procure adequate doses of vaccines, and coordinate their distribution. Monitoring of seroprevalence, therefore, at various time points is the key to better management of the COVID-19 situation.

This study was conducted with the aim to determine the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) antibodies in healthy blood donors in North India. Studying seroprevalence in blood donors was readily feasible as a “sample survey” since donors were representative of the regional population and it was far less expensive as compared to the screening of general population. This study would also help us to know the impact of the virus and the ongoing national vaccination drive on the community.


  Material and Methods Top


Settings

This prospective study was carried out in the department of transfusion medicine at a tertiary care hospital, NCR region of North India. The study was performed over a period of 2 months from April 2021 to May 2021. Whole blood donors from northern states (Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, Bihar, Uttar Pradesh, Uttaranchal, Himachal Pradesh, Punjab, and Haryana) and northern union territories (Ladakh, Jammu, Srinagar, Chandigarh, and Delhi) were included in the analysis.

Study population

The prospective donors were registered at the front desk of the blood center, and the donors were given predonation counseling by a trained counselor. They were administered medical history questionnaire, and a brief physical examination was carried out in accordance with the Directorate General of Health Services guidelines.[2] The medical examination included weight, temperature, blood pressure, pulse rate, and hemoglobin. Predonation Hb was estimated by a photometer (Compo Lab TS, Fresenius, Germany) in finger-prick blood samples.

Inclusion and exclusion criteria

Inclusion criteria

  1. All whole blood donors eligible for blood donation as per the guidelines and who gave consent for the study were included[2]
  2. Blood donors from the northern states.


Exclusion criteria

  1. Whole blood donors unable to donate blood or deferred due to any relevant medical history were excluded from the study
  2. Blood donors with a history of COVID-19 infection or vaccination in the past 14 days were excluded[2]
  3. Donors who came for repeat donation (s) were also excluded.


Tests for anti-severe acute respiratory syndrome antibody Screening

All blood donor samples for viral marker testing were screened for the presence of IgG antibodies against SARS CoV2 spike (S1) protein using anti-SARS CoV2 IgG antibody assay on VITROS platform (VITROS Immunodiagnostic Products Anti-SARS-CoV-2 IgG Test, Ortho-Clinical Diagnostics, Inc., NY, USA). Samples with signal/cutoff (S/co) value ≥1 were considered positive as per the manufacturer's instructions. Anti-SARS CoV2 IgG antibody is detectable after natural infection as well as postvaccination.

Data collection

Anti-SARS CoV2 IgG antibody status, demographic data (age and gender), history of past documented COVID infection (positive by reverse transcription polymerase chain reaction), and history of vaccination by single or double dose of Covishield or Covaxin of all eligible donors in the study period was collected for the data analysis. However, data were not analyzed separately on the basis of type and number of doses of vaccine. S/co values were also noted and donors were grouped into three categories on the basis of their S/co values. This was done in the context of finding by Joyner et al.,[3] who classified COVID convalescent plasma (CCP) donors into three groups: low-titer (<4.62), medium-titer (4.62–18.45), and high-titer (>18.45).

Statistical analysis

Seroprevalence was calculated as the percentage of total number of donors positive for anti-SARS CoV2 IgG antibodies. Month-wise seroprevalence was also calculated and analyzed.

Ethical approval

This study was approved by the institutional review board (IRB), reference number (1311/2021). The procedures followed were in accordance with the ethical standards of the committee on human experimentation and the Helsinki Declaration of 1964, as revised in 2013.


  Results Top


Demographics

In the present study, seroprevalence was estimated by testing blood donor samples for anti-SARS CoV2 IgG antibodies in the months of April and May 2021. A total of 1456 blood donors were included in the study. Majority of the donors (94.6%) were males. The median age of the donors was 30 years and the range was 18–50 years. Time interval between infection/vaccination and blood donation varied between 14 days and 3 months.

Seroprevalence

Out of 1456 donors, 874 were found to be seropositive, resulting in a seroprevalence of 60%. Seroprevalence was found to be 38.3% and 77%, respectively, in the months of April and May.

History of infection/vaccination

As shown in [Table 1], out of the total 1456 blood donors in the study period, 1188 had no history of past COVID-19 infection or vaccination, 164 had a history of vaccination only, 77 had history of COVID-19 infection only, and 27 had a history of both infection and vaccination.
Table 1: History of infection/vaccination in all whole blood donors who were screened (n=1456)

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As shown in [Figure 1], out of 874 (60%) seropositive-positive donors, 635 had no history of COVID-19 infection or vaccination in the past, 151 had received vaccination for COVID-19, 61 had history of COVID infection, and 27 had a history of both vaccination and infection.
Figure 1: Immunization and infection status of COVID19 in seropositive blood donors (n = 874)

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Potential convalescent plasma donors

Among 874 donors with positive anti-SARS-CoV-2 IgG test, 282, 418, and 174 could have qualified as CCP donors with low S/Co (<4.62), medium S/Co (4.62–18.45), and high S/Co (>18.45), respectively.[3]


  Discussion Top


Sero-prevalence

In the present study, seroprevalence of SARS-CoV-2 IgG antibodies was estimated to be 60% which is similar to the results of ICMR's fourth round of national serosurvey which recorded the overall sero-prevalence of 67.6% in the months of June and July.[4] However, we could not study the gender differences as the number of women donors was low (5.4%) in our study population which is in-line with the voluntary blood donation gender patterns in India in several Indian studies.[5],[6]

Seroprevalence in relation to health history

As shown in [Table 2], seropositivity was higher in those vaccinated, than those with only history of COVID 19 illness (92% vs. 79%). Available vaccines seem to be very effective, though we were not able to study the type of vaccine used, most of the subjects received the Covishield (Astra Zaneca, Serum Institute of India, Pune, India) or Covaxin (Bharat Biotech, Hyderabad, India) during the preceding months as per national trends. Seropositivity was not 100% in donors who had a history of either vaccination or infection alone. The absence of antibody response could be due to inaccurate history or “non-responders” to vaccine or infection. There is some data pointing toward induction of cellular immunity in those exposed to the virus even in the absence of antibody response, particularly those with asymptomatic or mild illness so the true level of protection may be higher than the seroprevalence data suggests.[7]
Table 2: Seropositivity in blood donors in relation to the history of vaccination and infection

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Another key finding of the study was the seropositivity rate of 100% in those with a history of both COVID illness and vaccination.

Since only 268/1456 (18%) donors had a history of COVID-19 infection or vaccination, although 60% were seropositive. In author's opinion, this mismatch (medical history vs. higher seroprevalence) was possibly due to sub-clinical illness or completely asymptomatic infection in several individuals.

Forty percent seronegative donor population, at that point-in-time, seems to correspond to significant proportion of vulnerable population at risk of COVID-19 in India.

We did observe an increase in seroprevalence from April to May (38.3%–77%) and this coincided with the fulminant second wave in India.[8]

Herd immunity

The seroprevalence rate found in our study was close to the overall seroprevalence of 67.6% found in ICMR's fourth round of national serosurvey conducted in the months of June-July 21 and was higher than the seroprevalence rates recorded in the earlier three national serosurveys, 0.7%, 7.1%, and 24.1% during May − June (2020), August − September (2020), and December − January (2020-21), respectively.[4] Sareen et al. found seroprevalence of 36.12% in healthy blood donors of Rajasthan during the months of September-November 2020 which was low in comparison to the present study but was close to the result of ICMRs third round of national serosurvey.[9] This is probably due to different time period of the studies. ICMR serosurvey results over the course of the pandemic, and together with our results, the data are pointing toward developing population level immunity for COVID-19 unless mutations alter the course of the pandemic.[4]

Limitations of the present study

Blood donor population may not exactly represent the general population. Data were not analyzed separately on the basis of type and number of doses of vaccine.


  Conclusion Top


Seroprevalence in the present study was 60% in the months of April − May 2021 and was highest in blood donors with a history of infection and vaccination both. Blood donors represent an easy access to sero-prevalence studies and need to be tapped at national level to obtain a temporal picture of the COVID-19 situation to guide healthcare policies, mark regions where vaccination drives need to be intensified.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
WHO Coronavirus Covid 19 Dashboard. Covid 19. Available from: http://who.int. [Last accessed on 2022 Aug 04].  Back to cited text no. 1
    
2.
Saran RK, editor. Transfusion Medicine: Technical Manual. New Delhi: Directorate General of Health Services, Ministry of Health and Family Welfare, Government of India; 2003.  Back to cited text no. 2
    
3.
Joyner MJ, Senefeld JW, Klassen SA, Mills JR, Johnson PW, Theel ES, et al. Effect of convalescent plasma on mortality among hospitalized patients with COVID-19: Initial three-month experience. medRxiv 2020. doi: 10.1101/2020.08.12.20169359. PMID: 32817978.  Back to cited text no. 3
    
4.
2 of 3 Indians Have Covid-19 Antibodies: ICMR Serosurvey Findings Explained. Available from: https://indianexpress.com/article/explained/explained-icmr-covid-fourth-serosurvey-findings-7413949/. [Last accessed on 2022 Aug 04].  Back to cited text no. 4
    
5.
Tiwari AK, Bhardwaj G, Arora D, Aggarwal G, Pabbi S, Dara RC, et al. Applying newer parameter Ret-He (reticulocyte haemoglobin equivalent) to assess latent iron deficiency (LID) in blood donors-study at a tertiary care hospital in India. Vox Sang 2018;113:639-46.  Back to cited text no. 5
    
6.
Shah AR, Shethwala ND, Parmar BH. Knowledge and awareness about Iron deficiency and megaloblastic anaemia among blood donors: A study at rural based tertiary care hospital. Int J Res Med Sci 2015;3:708.  Back to cited text no. 6
    
7.
Schwarzkopf S, Krawczyk A, Knop D, Klump H, Heinold A, Heinemann FM, et al. Cellular immunity in COVID-19 convalescents with PCR-confirmed infection but with undetectable SARS-CoV-2–specific IgG. Emerging infectious diseases 2021;27:122.  Back to cited text no. 7
    
8.
Available from https://www.worldometers.info/coronavirus/country/india/. [Last accessed on 2022 Aug 04].  Back to cited text no. 8
    
9.
Sareen R, Gupta GN, Agarwal P, Saini S. COVID-19 immunoglobulin G antibodies in healthy blood donors paving way to herd immunity. Glob J Transfus Med 2021;6:76-80.  Back to cited text no. 9
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    Figures

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    Tables

  [Table 1], [Table 2]



 

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