Home About us Editorial board Ahead of print Current issue Search Archives Submit article Instructions Subscribe Contacts Login 
  • Users Online:366
  • Home
  • Print this page
  • Email this page


 
 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 6  |  Issue : 2  |  Page : 198-204

Evaluation of donor demographic, clinical, and serological characteristics in COVID convalescent plasma donation by plasmapheresis


Department of Transfusion Medicine, Apollo Gleneagles Hospitals, Kolkata, West Bengal, India

Date of Submission22-Jul-2021
Date of Decision28-Sep-2021
Date of Acceptance05-Oct-2021
Date of Web Publication30-Nov-2021

Correspondence Address:
Dr. Sudipta Sekhar Das
Department of Transfusion Medicine, Apollo Gleneagles Hospitals, Kolkata, West Bengal
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/gjtm.gjtm_76_21

Rights and Permissions
  Abstract 


Background and Objectives: Passive transfusion of convalescent plasma (CCP) in coronavirus disease 2019 (COVID-19) has proven to be a winning and logistically feasible therapeutic strategy. The efficacy of plasma depends on appropriate donor screening and selection. Ours being a tertiary care hospital with dedicated COVID facility, we obtained prescriptions of CCP from clinicians for the treatment of COVID-19. Here, we discuss the clinical and serological characters of the voluntary donors who altruistically visited the blood center for plasma donation. Methods: The study included 683 voluntary donors who visited the blood center for mandatory eligibility screening to donate plasma. Donor eligibility criteria were applied following established guidelines. Donor details were obtained from blood center records and software. Detailed investigations on blood samples were performed as mandated and discussed. Results: Among 683 donors initially registered 166 (24.3%) were deferred due to various causes The median age of eligible donors was 44 years with a male preponderance. The mean anti- severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG (S/Co) was calculated to be 12.9. An upward trend in anti-SARS-CoV-2 IgG level was observed with increase in fever temperature, disease severity, and symptom-free days (P < 0.05). Conclusion: Donor screening and selection in CCP donation should be performed meticulously to obtain safe and potent plasma products. Based on our findings, we suggest that in addition to optimum anti-SARS-CoV-2 IgG levels, factors such as the severity of disease, fever temperature, and symptom-free days which determine antibody adequacy may be considered while selecting CCP donors.

Keywords: Antibody, anti-severe acute respiratory syndrome coronavirus 2, coronavirus disease 2019, donor screening, plasmapheresis


How to cite this article:
Das SS, Biswas RN, uz Zaman R, Sen S. Evaluation of donor demographic, clinical, and serological characteristics in COVID convalescent plasma donation by plasmapheresis. Glob J Transfus Med 2021;6:198-204

How to cite this URL:
Das SS, Biswas RN, uz Zaman R, Sen S. Evaluation of donor demographic, clinical, and serological characteristics in COVID convalescent plasma donation by plasmapheresis. Glob J Transfus Med [serial online] 2021 [cited 2022 Jan 18];6:198-204. Available from: https://www.gjtmonline.com/text.asp?2021/6/2/198/331623




  Introduction Top


The novel coronavirus disease 2019 (COVID-19) has affected the entire world with significant morbidities and mortalities. It is caused by an enveloped RNA virus named severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).[1],[2] COVID-19 is a contagious respiratory disease that mostly causes mild symptoms such as cough, low-grade fever, sore throat, and malaise but disease may progress into high fever, respiratory distress, pneumonia, and abdominal complications.[3],[4] To date, there is no proven effective therapy for COVID-19 and a number of treatment options such as antiviral drugs and/or immune modulators are on clinical trial.[1],[5] Adding to the woes, no vaccine is currently available. In situations, in which, the new virus is able to induce an immune response with the production of neutralizing antibodies, passive transfusion of COVID convalescent plasma (CCP) has proven to be a winning and logistically feasible therapeutic strategy.[6] A meta-analysis from 32 studies of SARS coronavirus infection and severe influenza showed a statistically significant reduction in the pooled odds of mortality following CCP therapy, compared with placebo or no therapy.[6] A recent pilot study on CCP therapy showed potential emergent therapeutic effect and low risk in COVID-19 patients.[7] The efficacy of CCP depends on appropriate donor selection and testing as described by the national or international guidelines.[8],[9],[10] Ours being a tertiary care hospital with dedicated COVID beds, we obtained prescriptions of CCP from clinicians for the treatment of COVID-19.

Aims and objectives

To study the clinical and serological characters of the voluntary donors who altruistically visited the blood center for CCP donation.


  Materials and Methods Top


Study design

The prospective study was conducted blood center of our hospital between June 10, 2020 and May 30, 2021.

Ethical approval was obtained from the Institute Ethics Committee (ECR/373/Inst/WB/2013/RR-19, dated 18/05/2020). The study included 683 voluntary donors who visited the blood center during the study period for mandatory eligibility screening to donate CCP.

Donor eligibility and selection

Donor eligibility criteria for CCP donation was followed as per the departmental standard operating procedures (SOPs) in accordance with the Drug and Cosmetics (DandC) Act 1940 and rules 1945 therein for plasmapheresis and guidelines prepared by the Director General of Health Services and Central Drugs Standard Control Organization in conjunction with the Indian Council of Medical Research, Government of India for the clinical trial of CP in COVID-19 patients.[9],[10],[11] To ensure optimal donor and staff safety guidelines provided by the National Blood Transfusion Council of India in the light of COVID pandemic were strictly followed and executed.[12] Social distancing, masking, hand hygiene, and cough etiquette were maintained strictly and ethically in the blood donation premises.

All prospective donors were registered and screened for age, weight, valid SARS-CoV-2 positive polymerase chain reaction (PCR) report, symptom-free status, parity status in females, primary blood group, medical history, drug history, fever history, vein status, and other mandatory selection parameters. For donors who qualified in the initial screening, whole blood (WB) samples were collected for laboratory screening as per the guidelines for donating CCP.[9],[10],[11]

Donor sampling and investigation

WB samples in EDTA and clotted vials were collected before CCP collection by plasmapheresis. The following investigations were performed on the collected samples sequentially.

  1. Hematological parameters such as platelets, hemoglobin (Hb), hematocrit, and WBC count were measured using a calibrated automated cell counter (iCount 3CP, IRIS Healthcare Technologies Private Limited, India)
  2. Blood group confirmation and antibody screening using automated solid-phase assay (NEO Iris, Immucor, USA)
  3. Serum protein using automated chemistry analyzer (Abbott Architect ci8200, Abbott Laboratories, USA)
  4. Qualitative detection of anti-SARS-CoV-2 IgG directed against domain S1 and S2 of the SARS-CoV-2 spike protein using the automated VITROS ECiQ immunodiagnostic system based on enhanced chemiluminescence technology (Ortho Clinical Diagnostics, USA)[13]
  5. Transfusion transmitted pathogens:


    1. Serology: Anti-HIV 1 and 2, anti-HCV, and HBsAg test were performed by the automated VITROS ECiQ immunodiagnostic system (Ortho Clinical Diagnostics, UK).  Treponema pallidum Scientific Name Search tibodies for syphilis were done by rapid qualitative, immunochromatography method (Medsource Ozone Biomedicals Pvt. Ltd. Haryana, India). Malaria antigens for Plasmodium falciparum and Plasmodium vivax were tested by rapid qualitative, chromatographic immunoassay (MicroGene Diagnostic Systems (P) Ltd, Thane, India)
    2. Nucleic acid testing (NAT): NAT for HIV, Hepatitis-B and Hepatitis-C viruses was performed using the automated cobas TaqScreen MPX v2.0 assays based on PCR technology (Roche Molecular Systems Inc.,Pleasanton, California, USA.).


Test and validation of anti-severe acute respiratory syndrome coronavirus 2 IgG serology

Briefly, the automated immunometric technique involves a two-stage reaction. In the first stage, antibodies to SARS-CoV-2 present in the sample bind with SARS-CoV-2 spike protein coated on wells. In the second stage, horseradish peroxidase (HRP)-labeled murine monoclonal anti-human IgG antibodies are added in the conjugate reagent. The conjugate binds specifically to the antibody portion of the antigen-antibody complex. After the washing step, the bound HRP conjugate is measured by a luminescent reaction and the light signals are read by the system. The amount of HRP conjugate bound is indicative of the amount of SARS-CoV-2 IgG antibody present. The manufacturer claims a specificity of 99.7% and a sensitivity of 90.0% for samples taken more than 15 days postsymptom onset.[13]

Interpretation of anti-severe acute respiratory syndrome coronavirus 2 IgG serology result[13]

Results are calculated by the device automated integrated systems.

Result = Signal for test sample ÷ Signal at Cutoff (S/Co value)

S/Co value of <1 suggests that the sample is nonreactive for anti-SARS-CoV-2 IgG and a value ≥1 suggests a reactive sample.

Although all anti-SARS-CoV-2 IgG reactive donors were considered eligible; however, samples with S/Co value ≥5 were primarily subjected to CCP donation as per the departmental SOP as well as directives from the hospital transfusion committee.

In-house control

Serum samples of COVID-19 patients who were RT-PCR positive and free from symptoms for ≥28 days were used as in-house positive control in the assay. All these samples were reported reactive for anti-SARS-CoV-2 IgG antibody from the microbiology department of the hospital. These positive controls were used for the validation of the test runs.

Classification of coronavirus disease 2019

COVID-19 was classified into mild, moderate, and severe depending on the severity of the disease as explained by previous authors.[14]

Statistical analysis

Statistical analysis was performed using the SPSS statistical package (IBM SPSS, 2015, Armonk, New York, USA). Donor details such as demography, clinical features, laboratory, and serological values, and hospitalization record were obtained from blood center software, CCP donor register, and patient discharge certificate. All values were captured in the MS office excel sheet and statistically analyzed. Quantitative variables were calculated as mean ± standard deviation or N (%). Quantitative variables were analyzed using the paired Student's t-test and “P” < 0.05 was considered statistically significant. Correlation between variables was studied by plotting specific values in a scattergram and calculating the correlation coefficient ® using Pearson's correlation test.


  Results Top


The present study included 683 voluntary donors who visited the blood center for donating CCP altruistically. Among 683 donors, initially registered 166 (24.3%) were deferred due to various causes [Table 1]. The major causes were poor venous access (15.1%) followed by multiparity in females (14.5%). A total of 517 donors were deemed eligible for CCP donation. The median age of eligible male and female donors was 47 and 40 years, respectively, with a male preponderance. The mean weight and body surface area of CCP donors were 67.9 kg and 1.66 m2, respectively. While the mean Hb value in male and female donors was observed to be 15.2 and 13.1 g/dL, respectively; the mean anti-SARS-CoV-2 IgG value (S/Co) was calculated to be 13.6 and 12.1, respectively [Table 2]. [Table 3] describes the clinical details of the eligible CCP donors. The most common self-reported clinical presentation at the time of illness was fatigue in males (326, 75.6%) and fever in females (75, 87.2%). A total of 387 (89.8%) male donors reported more than one symptom. No significant difference (P = 0.09) in mean anti-SARS-CoV-2 IgG levels was observed between donors with single and multiple symptoms. All eligible CCP donors were symptom-free for more than 28 days, reactive for anti-SARS-CoV-2 IgG antibody, and nonreactive for transfusion-transmitted pathogens. In terms of the severity of COVID-19, the majority of the donors had mild disease. A total of 103 (19.9%) donors needed hospitalization at the time of illness, with majority of them (45.3% males and 41.2% females) with the length of stay (LOS) of 10–15 days. Fever temperature could be retrieved from 243 donors and majority of them reported temperature between 37.5°C– 39.4°C (99.5°F-103°F). While no statistical significance was demonstrated between anti-SARS-CoV-2 IgG levels and donor's gender, age, and blood group; however, significance was observed between antibody levels and fever temperature as well as the severity of disease [Figure 1] and [Figure 2]. The mean anti-SARS-CoV-2 IgG value were 12.4 and 17.8 in donors with fever temperature 37.5°C–39.4°C and >39.4°C, respectively (P = 0.007). The mean anti-SARS-CoV-2 IgG levels of 8.2, 13.1, and 17.2 were observed in mild, moderate, and severe diseases, respectively (mild vs. moderate: P = 0.024, mild vs. severe: P = 0.008, and moderate vs. severe: P = 0.119). An upward trend in anti-SARS-CoV-2 IgG levels was observed with days of symptom-free status of donors. A significant positive correlation (r = 0.898, P = 0.029) was demonstrated between the donor antibody levels and symptom-free days [Figure 3].
Table 1: Donor deferral in convalescent plasma donation (n=166)

Click here to view
Table 2: Demographic and laboratory values of eligible convalescent plasma donors (n=517)

Click here to view
Table 3: Clinical details of eligible convalescent plasma donors

Click here to view
Figure 1: Significance of donor demography and blood group (x-axis) with anti-SARS CoV-2 IgG (S/Co) (n = 517) (y-axis)

Click here to view
Figure 2: Significance of donor fever temperature (n = 243) (x-axis) and disease severity (n = 517) (x-axis) with anti-SARS CoV-2 IgG (S/Co) (y-axis)

Click here to view
Figure 3: Correlation of donor symptom-free days and with anti-SARS CoV-2 IgG (S/Co) (n = 517)

Click here to view



  Discussion Top


The global health care facilities have undergone a significant disruption due to the present SARS-CoV-2 pandemic. The efficacy and safety of CCP have been discussed by previous authors elaborately.[15],[16] With regard to CCP donation, we observed reluctance among recovered COVID-19 patients during the initial period of the study. Fear of procedure and COVID reinfection were found to be the major causes of such unwillingness. Gradually with public awareness and induced or self-motivation more voluntary donors visited the blood center for screening and donating CCP. We believe that judicious and optimal donor selection in CCP donation is necessary for ensuring a safe and potent product. A study on donor evaluation for donating CCP is very limited in the literature.

We observed a male preponderance in the present study with a median age of 44 years among those who were found eligible. Clinical features and prognosis of COVID-19 vary among patients of different ages and younger patients showed lighter clinical manifestations and low severity.[17] We demonstrated that younger recovered patients (≤40 years of age) constituted the main donor population for CCP donation. Several donor deferral causes were observed which influenced the CCP donor inventory. Considerable numbers of female donors were deferred due to low Hb, poor venous access, low weight, or multiparity. Interestingly, 14 donors who had mild symptoms failed to reveal anti-SARS-CoV-2 IgG antibody (S/Co: 0.01–0.2) at the time of screening. Repeat test on fresh samples yielded the same result despite the high technical specificity and sensitivity of the serological assay. Further investigations on these samples were not possible owing to the limitation of resources. Previous authors have elucidated an age-dependent gender dimorphism for COVID-19, in which, the females have higher susceptibility but lower severity and fatality.[18] Although not statistically significant, emale eligible donors showed lower mean anti-SARS-CoV-2 IgG value compared to males (12.1 vs. 13.6). Low mean anti-SARS-CoV-2 IgG value was also demonstrated in donors >40 years of age [Figure 1]. Li et al. observed that 90% of eligible CCP donors were <50 years of age with 67% male donors.[19] Overall mean serum anti-SARS-CoV-2 IgG in the present study was 12.9 with a range of 5.8–28.2. Noticeable changes in S/Co values in identical samples were observed with lot-to-lot variation of reagents. We evaluated all new lots of reagent and calibrators before putting them into use following manufacturer's instruction. In-house controls were used for the evaluation of each new lot.

The majority of screened eligible donors in the current study belonged to “B” group (39.5%) followed by “O” (37.3%). No significant variation in anti-SARS-CoV-2 IgG levels was observed among various blood groups (P ≥ 0.21). Authors in the recent past concluded that blood group “A” was associated with a higher risk for acquiring COVID-19 compared with “non-A” blood groups, whereas blood group “O” was associated with a lower risk for the infection compared with “non-O” blood groups.[20] On the contrary in a large, multi-institutional review by Latz et al. there was no association noted between ABO blood type and COVID-19 disease severity.[21]

As per the report from the WHO–China Joint Mission on COVID-19, 80% of patients with laboratory-confirmed COVID-19 had mild-to-moderate disease, while 13·8% developed severe disease, and 6·1% developed to a critical stage requiring intensive care.[22] Accordingly, in the present study, fatigue, fever, and cough were the primary symptoms of the CCP donors during their illness, with majority (51.5%) of them having mild disease as defined by established criteria. As per the national guidelines, we accepted only those donors who had complete resolution of symptoms at least 28 days before CCP donation. This period ensures total clearance of the virus from the individual and ensures optimized production of anti-SARS-CoV-2 IgG in the blood circulation. Previous authors reported that anti-SARS-CoV-2 IgG antibodies were identifiable from day 7 onward, peaking at the 4th week, and thereby maintained at a high level for few weeks.[23] We observed that the majority (57%) of the eligible donors were free of symptoms for 34–43 days as also shown by Li et al.[19] Among the donors who were hospitalized at the time of illness, eight of them had a LOS of more than 20 days. One young male COVID survivor who needed ventilation support and discharged on the 39th day of hospitalization revealed a high anti-SARS-CoV-2 IgG value of 28.2. The alleged association between high anti-SARS-CoV-2 antibody levels and COVID-19 severity is a matter of concern. Previous authors have explained that patients experiencing severe COVID-19 are exposed to higher and more perdurable viral burdens and thereby produce high levels of antibody.[24],[25],[26],[27] Another study reported that high anti-SARS-CoV-2 antibody levels in severe COVID-19 represent an epiphenomenon in the setting of an overall exaggerated immune response driven by “cytokine storms.”[28] We demonstrated an increasing trend in anti-SARS-CoV-2 IgG level with the severity of the disease. Patients with moderate disease showed significantly higher levels of antibody compared to their mild counterparts (13.1 vs. 8.2, P = 0.024). Another interesting finding in this study was a significant increasing trend of anti-SARS-CoV-2 IgG level with donor fever temperature [Figure 2]. Li et al. reported that donors who experienced a body temperature exceeding 38.5°C or a fever lasting longer than 3 days had higher levels of anti-SARS-CoV-2 IgG antibody titers in CCP.

A recent publication by Long et al. indicated 100% IgG positivity at 17–19 days.[29] A study by Li et al. showed that nucleocapsid (N)-specific IgM antibody levels continued to decline after 3 weeks of SARS-CoV2 infection and reached low levels after 6 weeks. At the same time, spike protein (S)-specific and N-specific IgG antibodies exhibited an upward trend and continued to rise after 4 weeks from the onset of symptoms. These findings of the authors were also consistent with the study by Ni et al.[30] In similar notes, we also demonstrated an upward trend in anti-SARS-CoV-2 IgG levels with days of symptom-free status of donors and statistically calculated a significant positive correlation (r = 0.898, P = 0.029) between the donor S-specific IgG antibody levels and symptom-free days. We observed that the current study has several limitations. First, we failed to perform anti-SARS-CoV-2 neutralizing antibody titer due to the lack of expertise and infrastructures and second, anti-SARS-CoV-2 IgG titer was not done due to the lack of approved protocol, approved machine, and/or reagent. More large multi-centric studies are needed to verify the current findings and their significance.

Limitations of the study

  1. The study failed to perform anti-SARS-CoV-2 neutralizing antibody titer due to the lack of expertise and infrastructures. However, aliquot of serum samples of all eligible donors was stored at − 80°C for future neutralizing antibody titer test.
  2. The study failed to perform anti-SARS-CoV-2 IgG titer due to the lack of approved protocol, approved machine/reagent, and expertise.



  Conclusion Top


Donor screening and selection in CCP donation should be performed meticulously following guidelines established by national and international bodies. Based on our findings, we suggest that in addition to optimum anti-SARS-CoV-2 IgG levels, factors such as the severity of disease, fever temperature, and symptom-free days which determine antibody adequacy may be considered while selecting eligible COVID-19 CCP donors.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Cai X, Ren M, Chen F, Li L, Lei H, Wang X. Blood transfusion during the COVID-19 outbreak. Blood Transfus 2020;18:79-82.  Back to cited text no. 1
    
2.
Stanworth SJ, New HV, Apelseth TO, Brunskill S, Cardigan R, Doree C, et al. Effects of the COVID-19 pandemic on supply and use of blood for transfusion. Lancet Haematol 2020;7:e756-64.  Back to cited text no. 2
    
3.
Xu Z, Shi L, Wang Y, Zhang J, Huang L, Zhang C, et al. Pathological findings of COVID-19 associated with acute respiratory distress syndrome. Lancet Respir Med 2020;8:420-2.  Back to cited text no. 3
    
4.
Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: A descriptive study. Lancet 2020;395:507-13.  Back to cited text no. 4
    
5.
Ye Z, Rochwerg B, Wang Y, Adhikari NK, Murthy S, Lamontagne F, et al. Treatment of patients with nonsevere and severe coronavirus disease 2019: An evidence-based guideline. CMAJ 2020;192:E536-45.  Back to cited text no. 5
    
6.
Mair-Jenkins J, Saavedra-Campos M, Baillie JK, Cleary P, Khaw FM, Lim WS, et al. The effectiveness of convalescent plasma and hyperimmune immunoglobulin for the treatment of severe acute respiratory infections of viral etiology: A systematic review and exploratory meta-analysis. J Infect Dis 2015;211:80-90.  Back to cited text no. 6
    
7.
Duan K, Liu B, Li C, Zhang H, Yu T, Qu J, et al. Effectiveness of convalescent plasma therapy in severe COVID-19 patients. Proc Natl Acad Sci U S A 2020;117:9490-6.  Back to cited text no. 7
    
8.
The US Department of Health and Human Services, Food and Drug Administration. COVID-19 Convalescent Plasma Collection: Donor Eligibility, Processing, Labeling, and Distribution. AABB, Issued in April 2020 and Updated in May 2020. Available from: http://www.aabb.org/advocacy/regulatorygovernment/Documents/COVID-19-Convalescent-Plasma-Collection.pdf. ]Last accessed on 2021 Feb 11].  Back to cited text no. 8
    
9.
ICMR, Govt. of India. Phase II, Open Label, Randomized Controlled Trial to Assess the Safety and Efficacy of Convalescent Plasma to Limit COVID-19 Associated Complications in Moderate Disease. Available from: https://www.icmr.gov.in/ctechdocad.html. [Last accessed on 2020 Jul 22].  Back to cited text no. 9
    
10.
Govt. of India, Directorate General Health Services, Central Drugs Standard Control Organization. Clinical Trial of Convalescent Plasma in COVID-19 Patients. File No. X-11026/78/2020-BD Dated 17.04.2020. Available from: https://cdsco.gov.in/opencms/resources/UploadCDSCOWeb/2018/UploadPublic. [Last accessed on 2020 Apr 19]  Back to cited text no. 10
    
11.
Malik V. Drugs and Cosmetics Act, 1940 and Rules 1945 there in Amended Up to the 31st December, 2016. India: Eastern Book Company; 2016.  Back to cited text no. 11
    
12.
Second Interim, National Guidance to Blood Transfusion Services in India in Light of Covid-19 Pandemic. Available from: https://www.mohfw.gov.in/pdf/2nd NBTC guidance in lightof COVID19 pandemic.pdf. [Last accessed on 2020 Jun 25].  Back to cited text no. 12
    
13.
Evaluation of the Ortho Clinical Diagnostics Vitros Immunodiagnostic Products Anti-SARS-CoV-2 IgG Serology Assay for the Detection of Anti-SARS-CoV-2 Antibodies; 2020. Available from: https://www.gov.uk/government/publications/covid-19-laboratory-evaluations-of-serological-assays. [Last accessed on 2020 Oct 03].  Back to cited text no. 13
    
14.
Kogan A, Segel MJ, Ram E, Raanani E, Peled-Potashnik Y, Levin S, et al. Acute respiratory distress syndrome following cardiac surgery: Comparison of the American-European consensus conference definition versus the Berlin definition. Respiration 2019;97:518-24.  Back to cited text no. 14
    
15.
Chen L, Xiong J, Bao L, Shi Y. Convalescent plasma as a potential therapy for COVID-19. Lancet Infect Dis 2020;20:398-400.  Back to cited text no. 15
    
16.
Shen C, Wang Z, Zhao F, Yang Y, Li J, Yuan J, et al. Treatment of 5 critically ill patients with COVID-19 with convalescent plasma. JAMA 2020;323:1582-9.  Back to cited text no. 16
    
17.
Liu Y, Mao B, Liang S, Yang JW, Lu HW, Chai YH, et al. Association between age and clinical characteristics and outcomes of COVID-19. Eur Respir J 2020;55:2001112.  Back to cited text no. 17
    
18.
Qian J, Zhao L, Ye RZ, Li XJ, Liu YL. Age-dependent gender differences of COVID-19 in mainland China: Comparative study. Clin Infect Dis 2020;71:2488-94.  Back to cited text no. 18
    
19.
Li L, Tong X, Chen H, He R, Lv Q, Yang R, et al. Characteristics and serological patterns of COVID-19 convalescent plasma donors: Optimal donors and timing of donation. Transfusion 2020;60:1765-72.  Back to cited text no. 19
    
20.
Zhao J, Yang Y, Huang H, Li D, Gu D, Lu X, et al. Relationship between the ABO blood group and the COVID-19 susceptibility. medRxiv. Clinical Infectious Diseases 2021;73:328-31.  Back to cited text no. 20
    
21.
Latz CA, DeCarlo C, Boitano L, Png CY, Patell R, Conrad MF, et al. Blood type and outcomes in patients with COVID-19. Ann Hematol 2020;12:1-6.  Back to cited text no. 21
    
22.
WHO. Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). Available from: https://www.who.int/publications-detail/report-of-the-who-china-joint-mission-on-coronavirus-disease-2019-(covid-19).[Last accessed on 2020 Feb 28].  Back to cited text no. 22
    
23.
Liu X, Wang J, Xu X, Liao G, Chen Y, Hu CH. Patterns of IgG and IgM antibody response in COVID-19 patients. Emerg Microbes Infect 2020;9:1269-74.  Back to cited text no. 23
    
24.
Wang Y, Zhang L, Sang L, Ye F, Ruan S, Zhong B, et al. Kinetics of viral load and antibody response in relation to COVID-19 severity. J Clin Invest 2020;130:5235-44.  Back to cited text no. 24
    
25.
Liu L, To KK, Chan KH, Wong YC, Zhou R, Kwan KY, et al. High neutralizing antibody titer in intensive care unit patients with COVID-19. Emerg Microbes Infect 2020;9:1664-70.  Back to cited text no. 25
    
26.
Wölfel R, Corman VM, Guggemos W, Seilmaier M, Zange S, Müller MA, et al. Virological assessment of hospitalized patients with COVID-2019. Nature 2020;581:465-9.  Back to cited text no. 26
    
27.
Okba NM, Müller MA, Li W, Wang C, GeurtsvanKessel CH, Corman VM, et al. Severe acute respiratory syndrome coronavirus 2-specific antibody responses in coronavirus disease patients. Emerg Infect Dis 2020;26:1478-88.  Back to cited text no. 27
    
28.
Eroshenko N, Gill T, Keaveney MK, Church GM, Trevejo JM, Rajaniemi H. Implications of antibody-dependent enhancement of infection for SARS-CoV-2 countermeasures. Nat Biotechnol 2020;38:789-91.  Back to cited text no. 28
    
29.
Long QX, Liu BZ, Deng HJ, Wu GC, Deng K, Chen YK, et al. Antibody responses to SARS-CoV-2 in patients with COVID-19. Nat Med 2020;26:845-8.  Back to cited text no. 29
    
30.
Ni L, Ye F, Chen ML, Feng Y, Deng YQ, Zhao H, et al. Characterization of anti-viral immunity in recovered individuals infected by SARS-CoV-2. medRxiv 2020. [doi: 10.1101/2020.03.17.20036640].  Back to cited text no. 30
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Introduction
Materials and Me...
Results
Discussion
Conclusion
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed138    
    Printed14    
    Emailed0    
    PDF Downloaded25    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]