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ORIGINAL ARTICLE
Year : 2021 | Volume
: 46
| Issue : 2 | Page : 65-69
Seropositive coronavirus disease 2019 detection among apparently healthy voluntary blood donors: a preliminary step to catch asymptomatic cases as a potential viral spread route
Sahar S Abdelmaksoud1, Mariam K Youssef MD 1, Mahmoud M Aboulmagd2, Mariam F Abdelmaksoud1
1 Department of Clinical Pathology, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
2 Department of Pediatrics, Faculty of Medicine, MUST, Cairo, Egypt
Correspondence Address:
Mariam K Youssef
47 Osman Ebn Affan Street, Heliopolis, Cairo, 11361/11736
Egypt
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ejh.ejh_59_20
Background Despite the prevailing pandemic of coronavirus disease 2019, there are no recommendations available yet for serological screening of apparently healthy asymptomatic blood donors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies.
Objective To explore the seropositivity for SARS-CoV-2 antibodies in serum samples of a group of randomly selected Egyptian voluntary blood donors who met the eligibility criteria for blood donation as a preliminary step to catch apparently healthy asymptomatic participants who constitute an important source of viral spread in the community.
Patients and methods The first phase of our study design plan included 100 anonymous serum samples of a group of voluntary blood donors who donated blood at Ain-Shams University Hospitals’ blood bank during the period from the second week of September to the end of October 2020. After completion of the steps of donation, donors’ stored serum samples were screened for SARS-CoV-2-specific immunoglobulin (Ig)M and IgG antibodies. The next phase of our study design plan is intended to include larger samples of known apparently healthy asymptomatic blood donors in an attempt to reach seropositive patients to confirm the results by PCR and validate the testing.
Results A total of 100 anonymous serum samples were included in the study. Eleven (11%) samples were reactive for viral specific IgM antibodies, and 38 (38%) samples were reactive for viral specific IgG antibodies.
Conclusion As the ongoing pandemic of coronavirus disease 2019 is continuing to demand urgent attention, screening of all asymptomatic apparently healthy voluntary blood donors for SARS-CoV-2 antibodies followed by viral RNA detection by PCR in seropositive donors could abort viral spread to others in blood centers and eventually to the rest of the community.
Keywords: asymptomatic, blood donors, coronavirus disease 2019, seropositive
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19, first emerged in December 2019 in Wuhan, China, is regarded now a pandemic owing to its rapid transmission throughout the world [1]. SARS-CoV-2 is an enveloped beta coronavirus containing four major structural proteins: spike (S), membrane (M), envelope (E), and the nucleocapsid (N) [2]. The virus invades the host cells by interaction of its spike protein with specific receptor on host’s cell membrane (angiotensin converting enzyme-2 receptor), and then gains entry into the cell via endocytosis and uses its own RNA and host machinery for replication [3],[18].
COVID-19 has a wide range of presentation varying from no or mild symptoms like fever, dry cough, body aches, abdominal pain, and diarrhea to severe acute respiratory distress that could lead to multiorgan failure and death [4],[5]. The COVID-19 pandemic resembles an iceberg, what we can see is those who are severe cases, as well as part of mild to moderate cases and known asymptomatic cases diagnosed by screening of close contacts of COVID-19 cases, but an uncertain number of asymptomatic individuals and parts of mild cases remain missed [6].
SARS-CoV-2 transmits from human to human mainly through respiratory droplets. The virus has also been found in feces, urine, and conjunctival secretions of infected cases [7],[8], especially in the early stage of the disease [9]. In addition, viral RNA could be detected in plasma, serum, and whole blood before the onset of any symptom [10],[11]. Therefore, the potential for viral transmission via blood could indeed exist theoretically.
Centers for Disease Control and Prevention do not currently require any action on blood collection and testing because there are no data yet suggesting a risk of transfusion transmission of SARS-CoV-2 [12]. However, the European Center for Disease Prevention and Control (ECDC) implied a precautionary deferral of blood donation for 21 days after possible exposure to a confirmed COVID case; in addition, recovering confirmed COVID-infected patients should be deferred for at least 28 days after symptom resolution and completion of therapy [13].
As the infection continues to demand urgent attention and very close monitoring, the following points may be relevant to considerations regarding transfusion and organ transplantation: (a) viral RNA in plasma or serum could be detected in COVID-19-infected patients on the first 2 or 3 days of illness; (b) most patients, especially young adults who can donate blood, had milder symptoms than the older adults; (c) patients with no fever and asymptomatic carriers could donate blood; and (d) the rate of infectivity of patients who are in the incubation period remains uncertain, and there are no data on the viral load in plasma, serum, or lymphocytes among individuals in the incubation period [14]. Therefore, our study aimed at screening of serum samples of a cohort of randomly selected apparently healthy Egyptian voluntary blood donors for antibodies to SARS-CoV-2 to determine the urgent need for implementation of stricter precautionary measures in blood centers during the concurrent COVID-19 pandemic to limit viral spread in the community.
Patients and methodsStudy design
The first phase of our cross-sectional study included 100 anonymous serum samples of a group of randomly selected apparently healthy asymptomatic Egyptian blood donors who donated blood at Ain-Shams University Hospitals’ blood bank during the period from the second week of September 2020 to the end of October 2020. The next phase of our study design plan is intended to include larger samples of voluntary blood donors with known personal demographic data in an attempt to reach seropositive patients to confirm their results by PCR.
Study methodology
After fulfilling the eligibility criteria for blood donation and completion of the donation steps, donors’ serum samples were stored at 2–8°C for no longer than 3 days or at −20°C for longer duration. Stored samples were randomly collected and screened for SARS-CoV-2 specific immunoglobulin (Ig)M and IgG antibodies using AMP Rapid Test SARS-CoV-2 IgG/IgM (AMP diagnostics; AMEDA Laboradiagnostik GmbH, Graz, Austria). Test principle is as follows: AMP Rapid Test is a lateral flow immunoassay intended for the rapid immunochromatographic qualitative detection of IgM and IgG antibodies for SARS-CoV-2 in human whole blood, serum, and plasma samples. The test uses anti-human IgG (test line IgG), anti-human IgM (test line IgM), and rabbit IgG (control line C) immobilized on a nitrocellulose strip. The burgundy colored conjugate pad contains colloidal gold conjugated to recombinant COVID-19 antigens (SARS-CoV-2 Spike S1 antigen) conjugated with colloid gold (COVID-19 conjugates). When a specimen followed by assay buffer is added to the sample well, IgM and/or IgG antibodies, if present, will bind to COVID-19 conjugates making an antigen–antibody complex. This complex meets the line of the corresponding immobilized antibody (anti-human IgM and/or anti-human IgG) and is then trapped forming a burgundy colored band, which confirms a reactive test result. Absence of a colored band in the test region indicates a nonreactive test result. To serve as a control for the procedure, a colored line will always change from blue to red in the control line region, indicating that the proper specimen volume has been added, and membrane wicking has occurred. Sample testing was done as follows: donors’ stored serum samples were first brought to room temperature, then 5-μl serum was withdrawn from each sample using mini plastic droppers provided with the kit. The serum was immediately transferred to the sample well of the test cassette, after which ∼80 μl of buffer was applied in the buffer well. According to the manufacturer’s recommendations, the test results were recorded between 10 and 15 min.
Ethical consideration
The study was conducted in accordance with the ethical standards settled by the ethics committee of the Faculty of Medicine, Ain-Shams University, and was approved by the same committee. Only anonymous stored serum samples were included in the first phase of our study design plan. The next phase of our study design plan is intended to include larger samples of voluntary blood donors with known personal demographic data in an attempt to reach seropositive patients to confirm their results by PCR.
ResultsA total of 100 stored anonymous serum samples of voluntary blood donors, who donated blood during the period from the second week of September to the end of October 2020, were randomly collected and examined for COVID-19-specific IgM and IgG antibodies. Analysis of COVID-19 IgM in the total number of samples (100 samples) yielded 89% (89/100) nonreactive results, whereas 11% (11/100) were reactive. As for COVID-19 IgG, 62% (62/100) were not reactive and 38% (38/100) were reactive ([Table 1] and [Figure 1] and [Figure 2]).
Table 1 Results coronavirus disease 2019 immunoglobulin M and immunoglobulin G in 100 serum samples
Figure 1 Results of COVID-19 IgM in 100 serum samples. COVID-19, coronavirus disease 2019; IgM, immunoglobulin M.
Figure 2 Results of COVID-19 IgG in 100 serum samples. COVID-19, coronavirus disease 2019; IgG, immunoglobulin G. Discussion SARS-CoV-2 has spread rapidly throughout the world since the first cases of COVID-19 were detected in December 2019 in Wuhan, China. Infected persons who remain asymptomatic are thought to play an important role in the ongoing pandemic. Asymptomatic cases account for ∼40–50% of SARS-CoV-2 infections, and they can transmit the virus for an extended period, may be for longer than 14 days [15]. In addition, in some cases, the viral load of such asymptomatic persons has been equal to that of symptomatic cases, suggesting similar potential of viral transmission [16].
Currently, little information is known about the prevalence of SARS-CoV-2 antibodies in low-risk Egyptian population such as asymptomatic voluntary blood donors. Blood donors are considered an important source of viral spread in the community owning to the fact that most COVID-19-infected patients, especially young adults are asymptomatic and apparently healthy, and hence could donate blood and spread the virus to others in blood centers and eventually to the rest of the community.
In our study, 100 anonymous serum samples of a group of randomly selected Egyptian voluntary blood donors, who donated blood during the period from the second week of September to the end of October 2020, were screened for SARS-CoV-2-specific IgM and IgG antibodies. Although samples of those who were apparently healthy were included, blood donors who had fever or respiratory symptoms, had close contacts to known COVID-19 cases, and were recent travelers to areas with high disease epidemic were deferred by a predonation questionnaire. Overall, 11 (11%) of the tested serum samples were reactive for viral specific IgM antibodies, and 38 (38%) samples were reactive for viral specific IgG antibodies. A study by Xu et al. [17] on a cohort of apparently healthy Chinese blood donors who donated blood from 23 March to 2 April 2020, found that the seroprevalence of anti-SARS-CoV-2 IgM and IgG was 0 and 0.09%, respectively. Another study by Younas et al. [18] on voluntary blood donors during May to July 2020 in Pakistan found a seroprevalence of anti-SARS-CoV-2 IgM and IgG of 0 and 22%, respectively. The variation in the serological prevalence of viral antibodies could be linked to different disease epidemiology in the different populations. Moreover, the implementation of social restriction measures could differ in the different communities. Furthermore, our study duration was selected to include the beginning of the second wave of COVID-19.SARS-CoV-2 antibody production typically starts between 7 and 11 days after exposure to the virus. Zhao et al. [19] reported the median seroconversion time for anti-SARS-CoV-2 IgM to be 12 days and for IgG to be 14 days after disease onset. The IgM level declines significantly after 35 days from disease onset, whereas IgG remains for up to 4 years but with low titer. Therefore, in the first asymptomatic phase of the disease, the serological tests are more likely to give false-negative results. Moreover, antibody testing may give false-positive results with a variety of factors such as the presence of rheumatoid factor in serum [20].
Because of the high risk for viral spread by asymptomatic cases, it is imperative that screening programs include those without symptoms. Although viral RNA detection by PCR remains the investigation of choice for diagnosis of COVID-19, antibody testing cannot be used for diagnosis of true infection or to ensure the development of protective immunity against the virus. However, serological screening is cost-effective, does not require special equipment, and thus can be implemented in all blood centers even in those with limited capacities to detect the average number of asymptomatic apparently healthy blood donors who were exposed to the virus and constitute an important source of COVID-19 spread in the community.
This is the first phase of our study design plan to explore the seropositivity to SARS-CoV-2 antibodies in stored anonymous samples of apparently healthy asymptomatic blood donors. As the COVID-19 pandemic is still ongoing, the next phase of our study design plan is intended to be for longer duration and to include larger samples of apparently healthy blood donors with known personal demographic data in an attempt to reach seropositive patients to confirm the results by PCR and validate the testing.
ConclusionApparently healthy asymptomatic blood donors could be an important source of COVID-19 spread to others in blood centers and to the rest of the community. As the ongoing COVID-19 pandemic continues to demand urgent attention, stricter more specific precautionary measures, such as SARS-CoV-2 antibody screening for all voluntary blood donors followed by viral RNA detection by PCR in seropositive cases, are urgently needed to be implemented in blood centers in an attempt to abort viral spread in the community.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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