A retrospective study assessing the characteristics of COVID-19 convalescent plasma donors and donations

Hyperimmune Plasma and Immunoglobulins against COVID-19: A Narrative Review

Since late 2019, the new SARS-CoV-2 virus belonging to the Coronaviridae family has been responsible for COVID-19 pandemic, a severe acute respiratory syndrome. Several antiviral therapies, mostly derived from previous epidemics, were initially repurposed to fight this not rarely life-threatening respiratory illness. Among them, however, the only specific antibody-based therapy available against SARS-CoV-2 infection during the first year of the pandemic was represented by COVID-19 convalescent plasma (CCP). CCP, collected from recovered individuals, contains high levels of polyclonal antibodies of different subclasses able to neutralize SARS-CoV-2 infection. Tens of randomized controlled trials have been conducted during the last three years of the pandemic to evaluate the safety and the clinical efficacy of CCP in both hospitalized and ambulatory COVID-19 patients, whose main results will be summarized in this narrative review. In addition, we will present the current knowledge on the development of anti-SARS-CoV-2 hyperimmune polyclonal immunoglobulins.

Correlation between Clinical Characteristics and Antibody Levels in COVID-19 Convalescent Plasma Donor Candidates

COVID-19 convalescent plasma (CCP) with high neutralizing antibodies has been suggested in preventing disease progression in COVID-19. In this study, we investigated the relationship between clinical donor characteristics and neutralizing anti-SARS-CoV-2 antibodies in CCP donors. COVID-19 convalescent plasma donors were included into the study. Clinical parameters were recorded and anti-SARS-CoV-2 antibody levels (Spike Trimer, Receptor Binding Domain (RBD), S1, S2 and nucleocapsid protein) as well as ACE2 binding inhibition were measured. An ACE2 binding inhibition < 20% was defined as an inadequate neutralization capacity. Univariate and multivariable logistic regression analysis was used to detect the predictors of inadequate neutralization capacity. Ninety-one CCP donors (56 female; 61%) were analyzed. A robust correlation between all SARS-CoV-2 IgG antibodies and ACE2 binding inhibition, as well as a positive correlation between donor age, body mass index, and a negative correlation between time since symptom onset and antibody levels were found. We identified time since symptom onset, normal body mass index (BMI), and the absence of high fever as independent predictors of inadequate neutralization capacity. Gender, duration of symptoms, and number of symptoms were not associated with SARS-CoV-2 IgG antibody levels or neutralization. Neutralizing capacity was correlated with SARS-CoV-2 IgG antibodies and associated with time since symptom onset, BMI, and fever. These clinical parameters can be easily incorporated into the preselection of CCP donors.

The safety of plasma apheresis from donors recovering from COVID-19 infection in Japan

PURPOSE

Since 2020, the novel coronavirus infection (COVID-19) has spread globally. A few studies have investigated the safety of COVID-19 convalescent plasma (CCP) apheresis from COVID-19. This study was the first retrospective observational study of CCP in Japan.

METHODS

We recruit donors from April 2020 to November 2021 and plasmapheresis in our center (NCGM: national center for global health and medicine). We set the primary endpoint as the Donors Adverse Event (DAE) occurrence at the time of the CCP collection. Variable selection was used to explore the determinants of DAE.

RESULTS

Mean and SD age was 50.5 (10.6) years old. Seventy-three (42.2 %) were female, and 87 (33.3 %) were multiple-times donors. Twelve (6.97 % by donors and 4.6 % in total collections) adverse events occurred. The DAEs were VVR (Vaso Vagal Reaction), paresthesia, hypotension, agitation, dizziness, malaise, and hearing impairment/paresthesia. Half of them were VVR during apheresis. DAE occurred only in first-time donors and more in severe illnesses such as using ventilation and ECMO. From the donor characteristics and variable selection, the risk factors are as follows: younger age, female, the severity of disease at the time of the disease, and lower SBP before initiation. Our DAE incidence did not differ from previous studies. DAEs were more likely to occur in CCP apheresis than in healthy donors.

CONCLUSION

We confirm the safety of CCP apheresis in this study, although DAEs were more than healthy donors. More caution should be exercised in the plasma collection for future outbreaks of emerging infectious diseases.

Effectiveness of COVID-19 Convalescent Plasma (CCP) During the Pandemic Era: A Literature Review

Worldwide pandemic with coronavirus disease-2019 (COVID-19) was caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). As November 2, 2022, World Health Organization (WHO) received 628,035,553 reported incidents on COVID-19, with 6,572,800 mortalities and, with a total 12,850,970,971 vaccine doses have been delivered as of October 31, 2022. The infection can cause mild or self-limiting symptoms of pulmonary and severe infections or death may be caused by SARS-CoV-2 infection. Simultaneously, antivirals, corticosteroids, immunological treatments, antibiotics, and anticoagulants have been proposed as potential medicines to cure COVID-19 affected patients. Among these initial treatments, COVID-19 convalescent plasma (CCP), which was retrieved from COVID-19 recovered patients to be used as passive immune therapy, in which antibodies from cured patients were given to infected patients to prevent illness. Such treatment has yielded the best results in earlier with preventative or early stages of illness. Convalescent plasma (CP) is the first treatment available when infectious disease initially appears, although few randomized controlled trials (RCTs) were conducted to evaluate its effectiveness. The historical record suggests with potential benefit for other respiratory infections, as coronaviruses like Severe Acute Respiratory Syndrome-CoV-I (SARS-CoV-I) and Middle Eastern Respiratory Syndrome (MERS), though the analysis of such research is constrained by some non-randomized experiments (NREs). Rigorous studies on CP are made more demanding by the following with the immediacy of the epidemics, CP use may restrict the ability to utilize it for clinical testing, non-homogenous nature of product, highly decentralized manufacturing process; constraints with capacity to measure biologic function, ultimate availability of substitute therapies, as antivirals, purified immune globulins, or monoclonal antibodies. Though, it is still not clear how effectively CCP works among hospitalized COVID-19 patients. The current review tries to focus on its efficiency and usage in clinical scenarios and identifying existing benefits of implementation during pandemic or how it may assist with future pandemic preventions.

COVID-19 Convalescent Plasma and Clinical Trials: Understanding Conflicting Outcomes

Convalescent plasma (CP) recurs as a frontline treatment in epidemics because it is available as soon as there are survivors. The COVID-19 pandemic represented the first large-scale opportunity to shed light on the mechanisms of action, safety, and efficacy of CP using modern evidence-based medicine approaches. Studies ranging from observational case series to randomized controlled trials (RCTs) have reported highly variable efficacy results for COVID-19 CP (CCP), resulting in uncertainty. We analyzed variables associated with efficacy, such as clinical settings, disease severity, CCP SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antibody levels and function, dose, timing of administration (variously defined as time from onset of symptoms, molecular diagnosis, diagnosis of pneumonia, or hospitalization, or by serostatus), outcomes (defined as hospitalization, requirement for ventilation, clinical improvement, or mortality), CCP provenance and time for collection, and criteria for efficacy. The conflicting trial results, along with both recent WHO guidelines discouraging CCP usage and the recent expansion of the FDA emergency use authorization (EUA) to include outpatient use of CCP, create confusion for both clinicians and patients about the appropriate use of CCP. A review of 30 available RCTs demonstrated that signals of efficacy (including reductions in mortality) were more likely if the CCP neutralizing titer was >160 and the time to randomization was less than 9 days. The emergence of the Omicron variant also reminds us of the benefits of polyclonal antibody therapies, especially as a bridge to the development and availability of more specific therapies.

Analysis of 52 240 source plasma donors of convalescent COVID-19 plasma: Sex, ethnicity, and age association with initial antibody levels and rate of dissipation

Background

COVID‐19 convalescent plasma (CCP) was approved under emergency authorization to treat critically ill patients with COVID‐19 in the United States in 2020. We explored the demographics of donors contributing plasma for a hyperimmune, plasma‐derived therapy to evaluate factors that may be associated with anti‐SARS‐CoV‐2 antibody response variability and, subsequently, antibody titers.

Study Design

An electronic search of CCP donors was performed across 282 US plasma donation centers. Donations were screened for nucleocapsid protein‐binding‐IgG using the Abbott SARS‐CoV‐2 IgG assay.

Results

Overall, 52 240 donors donated 418 046 units of CCP. Donors were of various ethnicities: 43% Caucasian, 34% Hispanic, 17% African American, 2% Native American, 1% Asian, and 3% other. Females had higher initial mean anti‐SARS‐CoV‐2 antibody titers but an overall faster rate of decline (P < .0001). Initial antibody titers increased with age: individuals aged 55 to 66 years had elevated anti‐SARS‐CoV‐2 titers for longer periods compared with other ages (P = .0004). African American donors had the lowest initial antibody titers but a slower rate of decline (P < .0001), while Caucasian (P = .0088) and Hispanic (P = .0193) groups had the fastest rates of decline. Most donor antibody levels decreased below the inclusion criteria (≥1.50) within 30 to 100 days of first donation, but donation frequency did not appear to be associated with rate of decline.

Conclusion

Several factors may be associated with anti‐SARS‐CoV‐2 antibody response including donor age and sex. Evaluating these factors during development of future hyperimmune globulin products may help generation of therapies with optimal efficacy.

Development and implementation of a COVID-19 convalescent plasma program in a middle-income economy

Introduction

Convalescent Plasma therapy is one of the therapeutic strategies that has been used for patients with the Covid-19 disease. Implementing a program with national extension to supply hospitals with this blood component is a great challenge mainly in a middle-income economy.

Objectives

Our objective was to develop and implement a Covid-19 Convalescent Plasma Program which met established quality standards and was adapted to a reality of limited resources.

Methods

A multicentric convalescent plasma collection program was developed and implemented, based on four main sequential procedures: selective donor recruitment, pre-donation antibody screening (Anti-SARS-CoV-2- Chemiluminescence IgG Abbott), convalescent plasma collection by apheresis or whole-blood processing and distribution to the hospitals according to local demand.

Results

From the 572 candidates submitted to the pre-donation antibody screening, only 270 (47%) were considered eligible for plasma donation according to the established criteria. Higher levels of total antibody were associated with the donor age being above 45 years old (p = 0.002), hospital admission (p = 0.018), and a shorter interval between the diagnosis of the SARS-CoV-2 infection and plasma donation (p < 0.001). There was no association between the ABO and Rh blood groups and their antibody levels. Of the 468 donations made, 61% were from the collection of whole-blood and 39%, from apheresis. The Covid-19 Convalescent Plasma units obtained were distributed to 21 different cities throughout the country by air or ground transportation.

Conclusion

The implementation of a Covid-19 Convalescent Plasma program in a continental country with relatively scarce resources is feasible with alternative strategies to promote lower cost procedures, while complying with local regulations and meeting quality standards.

Convalescent Plasma for Hospitalized COVID-19 Patients: A Single-Center Experience

In Winter 2020, Italy, and in particular the Lombardy region, was the first country in the Western hemisphere to be hit by the COVID-19 pandemic. Plasma from individuals recovered from COVID-19 (COVID-19 convalescent plasma, CCP) was the first therapeutic tool adopted to counteract the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In this retrospective cohort study, we report the experience of the city hospital of Mantua, Lombardy region, on the compassionate use of CCP in patients hospitalized for severe COVID-19. Between April 2020 and April 2021, 405 consecutive COVID-19 patients received 657 CCP units with a median anti-SARS-CoV-2 neutralizing antibody (nAb) titer of 160 (interquartile range (IQR), 80−320). Their median age was 68 years (IQR, 56−78 years), and 62% were males. At enrollment, 55% of patients had an increased body mass index (BMI), and 25.6% had at least three comorbidities. The 28-day crude mortality rate was 12.6% (51/405). Young age (<68 years), mild disease (admission to low-intensity departments) and early treatment (<7 days from symptoms onset) with high nAb titer (≥320) CCP were found as independently associated with a favorable response to CCP treatment. No safety concerns were recorded, with a rate of CCP-related adverse reactions (all of mild intensity) of 1.3%. In our real-life experience, the first in the western world, early administration of high-titer CCP was a safe and effective treatment for hospitalized COVID-19 patients.

Analysis of responses of the health care workers recovered from COVID-19 on convalescent plasma donation by apheresis: A single-center survey study

Background

The COVID‐19 convalescent plasma (CCP) has been tried as a therapy in moderate COVID‐19 pneumonia. Donation of CCP requires motivation from recovered patients. This study evaluated the response of such recovered health care workers (HCWs) when they were motivated for CCP donation.

Methods

An interview‐based survey was carried out with recovered HCWs as study participants between August 2020 and November 2020. A qualified social worker explained the details of CCP donation over a mobile call; he clarified all their doubts and motivated them for the plasma donation. Their responses were recorded as “interested” or “not interested” followed by analysis.

Results

We tried to call 624 recovered HCWs, but could not reach 213, and the final group available for the study was 411 participants. Of these 411, 186 were deferred. Finally, we analyzed a total of 225 responses. Eventually, 105 out of 225 HCWs (47%) were interested; there were no significant differences in responses among males and females and between different age groups (<.001) and the “doctors” designation category (P = .01) had a maximum number of “interested” responses. In multivariate logistic regression, only the “interested” responses of the doctors were significantly higher after adjusting the confounding effect of the “graduate and above” educational qualification category.

Conclusion

This study found that nearly half of the eligible HCWs were interested in CCP donation. The educational qualification and designation among the recovered HCWs had an impact on CCP donation interest. The doctors were more interested in CCP donation compared to others.

SARS-CoV-2 variants inactivation of plasma units using a riboflavin and ultraviolet light-based photochemical treatment

Background

Test the ability of Mirasol Pathogen Reduction Technology (PRT, Terumo BCT, Lakewood Co, USA) treatment with riboflavin and ultraviolet light (R + UV) in reducing SARS-CoV-2 infectivity while maintaining blood product quality.

Material and methods

SARS-CoV-2 strains were isolated and titrated to prepare cell free virus for plasma units infection. The units were then under treatment with Mirasol PRT. The infectious titers were determined before and after treatment with an in house microtitration assay on Vero E6 cells. Thirty-six plasma pool bags underwent PRT treatment.

Results

In all the experiments, the measured titer following riboflavin and UV treatment was below the limit of detection of microtitration assay for all the different SARS-CoV-2 strains. Despite the high copies number detected by RT-PCR for each viral strain after treatment, viruses were completely inactivated and not able to infect VERO E6 cells.

Conclusion

Riboflavin and UV light treatment effectively reduced the virus titers of human plasma to the limit of detection in tissue culture, regardless of the strain. These data suggest that pathogen reduction in blood products highlight the safety of CP therapy procedures for critically ill COVID-19 patients, while maintaining blood product quality.

Mini-review: The market growth of diagnostic and therapeutic monoclonal antibodies - SARS CoV-2 as an example

BACKGROUND

The emergence of novel viruses poses severe challenges to global public health highlighting the crucial necessity for new antivirals.

MAIN BODY

Monoclonal antibodies (mAbs) are immunoglobulins that bind to a single epitope. Mouse mAbs are generated by classic hybridoma technology and are mainly used for immunodiagnostics. For immunotherapy, it is critical to use monoclonal antibodies in their human form to minimize adverse reactions. They have been successfully used to treat numerous illnesses, accordingly, an increasing number of mAbs, with high potency against emerging viruses is the target of every biopharmaceutical company. The diagnostic and therapeutic mAbs market grows rapidly into a multi-billion-dollar business. Biopharmaceuticals are innovative resolutions which revolutionized the treatment of significant chronic diseases and malignancies. Currently, a variety of therapeutic options that include antiviral medications, monoclonal antibodies, and immunomodulatory agents are available for the management of COVID-19.

SHORT CONCLUSION

The invasion of mAbs in new medical sectors will increase the market magnitude as it is expected to generate revenue of about 300 billion $ by 2025. In the current mini-review, the applications of monoclonal antibodies in immune-diagnosis and immunotherapy will be demonstrated, particularly for COVID-19 infection and will focus mainly on monoclonal antibodies in the market.

Antibody therapy for COVID-19

PURPOSE OF REVIEW

To provide an update of the current state of antibody therapy for Severe Acute Respiratory Syndrome Coronavirus 2 infection that has progressed immensely in a very short time period.

RECENT FINDINGS

Limited clinical effect of classical passive immunotherapy (plasma therapy, hyperimmune immunoglobulin [IgG] preparations) whereas monoclonal antibody therapy, if initiated early in the disease process, shows promising results.

SUMMARY

Although antibody therapy still remains to be fully explored in patients with COVID-19, a combination of IgG monoclonal antibodies against the receptor-binding domain of the spike protein currently appears to provide the best form of antibody therapy, Immunoglobulin A dimers and Immunoglobulin M pentamers also show promising preliminary therapeutic results.

SARS-CoV-2 Reinfection Is a New Challenge for the Effectiveness of Global Vaccination Campaign: A Systematic Review of Cases Reported in Literature

Reinfection with SARS-CoV-2 seems to be a rare phenomenon. The objective of this study is to carry out a systematic search of literature on the SARS-CoV-2 reinfection in order to understand the success of the global vaccine campaigns. A systematic search was performed. Inclusion criteria included a positive RT-PCR test of more than 90 days after the initial test and the confirmed recovery or a positive RT-PCR test of more than 45 days after the initial test that is accompanied by compatible symptoms or epidemiological exposure, naturally after the confirmed recovery. Only 117 articles were included in the final review with 260 confirmed cases. The severity of the reinfection episode was more severe in 92/260 (35.3%) with death only in 14 cases. The observation that many reinfection cases were less severe than initial cases is interesting because it may suggest partial protection from disease. Another interesting line of data is the detection of different clades or lineages by genome sequencing between initial infection and reinfection in 52/260 cases (20%). The findings are useful and contribute towards the role of vaccination in response to the COVID-19 infections. Due to the reinfection cases with SARS-CoV-2, it is evident that the level of immunity is not 100% for all individuals. These data highlight how it is necessary to continue to observe all the prescriptions recently indicated in the literature in order to avoid new contagion for all people after healing from COVID-19 or becoming asymptomatic positive.

Knowledge and Attitudes of Young Adults Towards Donation of COVID-19 Convalescent Plasma and Its Therapeutic Properties

PURPOSE

The aim of this study is to investigate the level of knowledge of the young adults towards the possible use of the convalescent plasma (CP) in the treatment of COVID-19 infection and their attitudes towards its donation.

METHODS

Cross-sectional questionnaire was administered online to 1058 university students, representing 4 different colleges. The questionnaire included demographic data and 20 questions related to the knowledge and attitudes of respondents about possible use of the convalescent plasma in the treatment of COVID-19 infection and its donation. Comparative analyses were made using the Mann-Whitney and Kruskal-Wallis tests and the Spearman correlation coefficient.

RESULTS

Significant relationships were found between dependent variables (level of knowledge and intensity of attitude) and gender, age, and student's college affiliation. There was no statistically significant correlation between dependent variables and respondents' social background and religious commitment. Studied young adults show a satisfactory knowledge relating to the therapeutic and preventive properties of the COVID-19 convalescent plasma. They also express a sufficient intensity of positive attitude towards CP donation.

CONCLUSION

This study confirms the need for appropriate health promotional campaigns and educational programs aimed at popularization of CP donation in the general public, which would increase the chances of involving more patients recovered from COVID-19 disease.

The safety of COVID-19 convalescent plasma donation: A multi-institutional donor hemovigilance study

BACKGROUND

Although the safety and therapeutic efficacy of COVID-19 convalescent plasma (CCP) has been extensively evaluated, the safety of CCP donation has not been explored in a multi-institutional context.

STUDY DESIGN AND METHODS

Nine blood collection organizations (BCOs) participated in a multi-institutional donor hemovigilance effort to assess the safety of CCP donation. Donor adverse events (DAEs) were defined according to the Standard for Surveillance of Complications Related to Blood Donation, and severity was assessed using the severity grading tool. Multivariate analysis was performed to determine attributes associated with DAE severity.

RESULTS

The overall DAE rate was 37.7 per 1000 donations. Repeat apheresis and apheresis-naïve donors experienced adverse event rates of 19.9 and 49.8 per 1000 donations, respectively. Female donors contributed 51.9% of CCP donations with a DAE rate of 49.4 per 1000 donations. The DAE rate for male donors was 27.4 per 1000 donations. Vasovagal reactions accounted for over half of all reported DAEs (51.1%). After adjustment, volume of CCP donated was associated with vasovagal reaction severity (odds ratio [OR] 6.5, 95% confidence interval [CI] 2.5-17.1). Donor age and donation history were also associated with DAE severity. Considerable differences in DAE types and rates were observed across the participating BCOs despite the use of standardized hemovigilance definitions.

CONCLUSION

The safety of CCP donation appears comparable to that of conventional apheresis plasma donation with similar associated risk factors for DAE types and severity.

Clinical predictors of SARS-CoV-2 neutralizing antibody titers in COVID-19 convalescents: Implications for convalescent plasma donor recruitment

While COVID-19 convalescent plasma (CCP) efficacy is still under investigation in randomized controlled trials (RCT), CCP collections continue worldwide with largely variable criteria. Since it is well known that only a minority of patients develop high-titer neutralizing antibodies (nAb), as assessed by the viral neutralization tests (VNT), strategies to maximize cost-effectiveness of CCP collection are urgently needed. A growing amount of the population is having exposure to the virus and is hence becoming a candidate CCP donor. Laboratory screening with high-throughput serology has good correlations with the VNT titer, but upstream screening using clinical surrogates would be advisable. We review here the existing literature on clinical predictors of high-titer nAb. Older age, male sex, and hospitalization are the main proxies of high VNT and should drive CCP donor recruitment.

Feasibility of collecting and processing of COVID-19 convalescent plasma for treatment of COVID-19 in Uganda

Introduction

Evidence that supports the use of COVID-19 convalescent plasma (CCP) for treatment of COVID-19 is increasingly emerging. However, very few African countries have undertaken the collection and processing of CCP. The aim of this study was to assess the feasibility of collecting and processing of CCP, in preparation for a randomized clinical trial of CCP for treatment of COVID-19 in Uganda.

Methods

In a cross-sectional study, persons with documented evidence of recovery from COVID-19 in Uganda were contacted and screened for blood donation via telephone calls. Those found eligible were asked to come to the blood donation centre for further screening and consent. Whole blood collection was undertaken from which plasma was processed. Plasma was tested for transfusion transmissible infections (TTIs) and anti-SARS CoV-2 antibody titers. SARS-CoV-2 testing was also done on nasopharyngeal swabs from the donors.

Results

192 participants were contacted of whom 179 (93.2%) were eligible to donate. Of the 179 eligible, 23 (12.8%) were not willing to donate and reasons given included: having no time 7(30.4%), fear of being retained at the COVID-19 treatment center 10 (43.5%), fear of stigma in the community 1 (4.3%), phobia for donating blood 1 (4.3%), religious issues 1 (4.4%), lack of interest 2 (8.7%) and transport challenges 1 (4.3%). The median age was 30 years and females accounted for 3.7% of the donors. A total of 30 (18.5%) donors tested positive for different TTIs. Antibody titer testing demonstrated titers of more than 1:320 for all the 72 samples tested. Age greater than 46 years and female gender were associated with higher titers though not statistically significant.

Conclusion

CCP collection and processing is possible in Uganda. However, concerns about stigma and lack of time, interest or transport need to be addressed in order to maximize donations.

We stand ready … Blood collection organizations and the COVID-19 pandemic

See article on page 1471–1478, in this issue

Donors for SARS-CoV-2 Convalescent Plasma for a Controlled Clinical Trial: Donor Characteristics, Content and Time Course of SARS-CoV-2 Neutralizing Antibodies

BACKGROUND

Convalescent plasma is one of the treatment options for COVID-19 which is currently being investigated in many clinical trials. Understanding of donor and product characteristics is important for optimization of convalescent plasma.

METHODS

Patients who had recovered from CO-VID-19 were recruited as donors for COVID-19 convalescent plasma (CCP) for a randomized clinical trial of CCP for treatment of severe COVID-19 (CAPSID Trial). Titers of neutralizing antibodies were measured by a plaque-reduction neutralization test (PRNT). Correlation of antibody titers with host factors and evolution of neutralizing antibody titers over time in repeat donors were analysed.

RESULTS

A series of 144 donors (41% females, 59% males; median age 40 years) underwent 319 plasmapheresis procedures providing a median collection volume of 850 mL and a mean number of 2.7 therapeutic units per plasmapheresis. The majority of donors had a mild or moderate course of COVID-19. The titers of neutralizing antibodies varied greatly between CCP donors (from <1:20 to >1:640). Donor factors (gender, age, ABO type, body weight) did not correlate significantly with the titer of neutralizing antibodies. We observed a significant positive correlation of neutralization titers with the number of reported COVID-19 symptoms and with the time from SARS-CoV-2 diagnosis to plasmapheresis. Neutralizing antibody levels were stable or increased over time in 58% of repeat CCP donors. Mean titers of neutralizing antibodies of first donation and last donation of repeat CCP donors did not differ significantly (1:86 at first compared to 1:87 at the last donation). There was a significant correlation of neutralizing antibodies measured by PRNT and anti-SARS-CoV-2 IgG and IgA antibodies which were measured by ELISA. CCP donations with an anti-SARS-CoV-2 IgG antibody content above the 25th percentile were substantially enriched for CCP donations with higher neutralizing antibody levels.

CONCLUSION

We demonstrate the feasibility of collection of a large number of CCP products under a harmonized protocol for a randomized clinical trial. Titers of neutralizing antibodies were stable or increased over time in a subgroup of repeat donors. A history of higher number of COVID-19 symptoms and higher levels of anti-SARS-CoV-2 IgG and IgA antibodies in immunoassays can preselect donations with higher neutralizing capacity.

Potential mechanisms of action of convalescent plasma in COVID-19

The COVID-19 pandemic will be remembered as one of the worst catastrophic events in human history. Unfortunately, no universally recognized effective therapeutic agents are currently available for the treatment of severe SARS-CoV-2 infection. In this context, the use of convalescent plasma from recovered COVID-19 patients has gained increasing interest thanks to the initially positive clinical reports. A number of mechanisms of action have been proposed for convalescent plasma, including direct neutralization and suppression of viremia, anti-inflammatory and immunomodulation effects and mitigation of the COVID-19-associated hypercoagulable state. These immune and non-immune mechanisms will be critically discussed in this narrative review.

Donor tolerability of convalescent plasma donation

Background

Since early 2020, convalescent plasma has been widely used for treating coronavirus disease 2019 (COVID‐19). There is limited information regarding donor tolerability of convalescent plasma donation. In this study, we evaluated the short‐term donor tolerability of convalescent plasma donation.

Methods

A prospective study of 309 convalescent plasma donation related adverse events were conducted at Wuhan Blood Center of China, from February 12 to April 1, 2020. Additionally, up to 28‐day post‐donation follow‐ups were performed on the donors.

Results

Sixteen (5.2%) adverse events were reported in 309 donations. All of these were mild vasovagal without loss of consciousness. The frequency of adverse reactions was higher in donors with a per donation volume of >8 mL/kg body weight or ≥ 600 mL, <100 mm Hg in pre‐donation systolic blood pressure, or less than 28 days from the onset of COVID‐19 symptoms. There was no correlation to donation history, weight, sex, ABO blood type, pre‐donation diastolic blood pressure, pulse, or hemoglobin.

Conclusion

The donation of convalescent plasma is generally safe. Mitigation of risk factors associated with adverse events can further enhance donor tolerability of convalescent plasma donation.

SARS-COV-2, can you be over it?

OBJECTIVES

Uncertainty has surrounded the duration of immunity against SARS CoV-2. This concerns both the duration of vaccine immunity and the duration of natural immunity. We aim to critically review the information available today, and draw practical conclusions.

METHODS

This is a narrative review of the recently published information on the topic, compared with the knowledge we already have of the behavior of various viral infectious agents.

RESULTS

It is too early to have any meaningful information on the duration of vaccine immunity against SARS CoV-2. For those who already had the infeciton, the rate of reinfection is very low. Most reinfections are due to laboratory errors, to incomplete cure of the primary infection, to the supervening immunodeficiency of the host, or to pre-existing immunodeficiency made evident by the SARS CoV-2 infection. The available studies on the immunology of the infection converge in indicating that it generates a robust and persistent immunity. This behavior does not differ from that of respiratory viruses known to date: in naturally occurring viral respiratory infections, reinfections are exceptional.

CONCLUSIONS AND IMPLICATIONS

The civil community awaits suggestions from scientists not only to protect susceptible people, but to be able to safely resume activities made uncertain by the pandemic. From the information we have to-date, we suggest that, in principle, patients who have already overcome the infection should not be prioritized to the SARS CoV-2 vaccine. Instead, they could be provided with an immunological passport that allows them to resume a normal social life.