Seroconversion and Abundance of IgG Antibodies against S1-RBD of SARS-CoV-2 and Neutralizing Activity in the Chilean Population.

COVID-19 is a pandemic caused by SARS-CoV-2. In Chile, half a million people have been infected and more than 16,000 have died from COVID-19. As part of the clinical trial NCT04384588, we quantified IgG against S1-RBD of SARS-CoV-2 (anti-RBD) in recovered people in Santiago and evaluated their suitability as COVID-19 convalescent plasma donors. ELISA and a luminescent SARS-CoV-2 pseudotype were used for IgG and neutralizing antibody quantification. 72.9% of the convalescent population (468 of 639) showed seroconversion (5-55 µg/mL anti-RBD IgG) and were suitable candidates for plasma donation. Analysis by gender, age, and days after symptom offset did not show significant differences. Neutralizing activity correlated with an increased concentration of anti-RBD IgG (p < 0.0001) and showed a high variability between donors. We confirmed that the majority of the Chilean patients have developed anti-SARS-CoV-2 antibodies. The quantification of anti-RBD IgG in convalescent plasma donors is necessary to increase the detection of neutralizing antibodies.

Results of a chilean nation-wide network of blood banks for convalescent plasma collection for pandemic SARS-CoV-2 treatment

Background/Case Studies: The SARS-CoV-2 pandemic has left more than 650.000 diseased worldwide, without a specific treatment nor vaccine, leaving patients with risk factors, like cancer or severe illness, without therapeutic options. Convalescent plasma, previously described in viral infections, has proved to be safe and effective. Here, we describe our findings in specific donor population studied. Study Design/Methods: Across social media, a call was made for COVID-19 recovered patients to donate convalescent plasma. There were considered male donors and female donors with and without pregnancy records. Volunteers were tested for IgG anti SARS-CoV-2 antibodies titers, HIV, HCV, HBV, Chagas disease, HTLV I and II, syphilis and were performed NAT for HIV, HBV and HCV. All women and men with blood transfusions records had anti HLA antibodies measured. The characteristics of age, sex, antibody titers, anti HLA antibodies, blood group, and its relationship with the severity of the infection are described. Results/Findings: Data analysis included 864 patients tested. 22,7% had IgG titers less than 1:320, while 31% had titers of 1:320, and 31% had titer at least 1:640. 15,3% was deferred because microbiologic studies (8 donors) or anti HLA antibodies (124 patients). From group with less than 1:320, the average age was 37,5 years, 44,3% were women, and 100% had mild infection requiring no hospitalization, while the 1:320 titers group had an average age of 34 years, with a 50% of women. For group with at least 1:640 titers, average age was 38 years, with a 44% of women. The major proportion of donors with severe illness were fromO (+) factor. From all tested women, a 26,6% had anti HLA (+) antibodies. From 4 male donors with history of transfusion, 1 had anti HLA (+) antibodies. Conclusions: In our population, 73% of potential donors had enough IgG antibodies to be collected. Including women with pregnancy record, makes possible increase the universe of convalescent plasma donors.

A strategy for SARS-CoV-2 convalescent plasma collection in a chilean nation-wide blood bank network

Background/Case Studies: With SARS-CoV-2 pandemic, and the potential use of convalescent plasma, most blood banks were forced to coordinate calling strategies, donor selection, and convalescent plasma production, with no new resources. The first infected patient in Chile was reported on March 03, 2020. The objective of this study is to describe our selection strategy and its efficiency. Study Design/Methods: The project was approved by the ethics committee. In our country, a multicentric nation-wide network of blood banks was created, with eight centers collecting convalescent plasma. A donor registration web site was created with volunteer inscription, which had specific questions that could result in an immediate deferral, and this web site was promoted on TV and in social media. After that phase, a brief telephonic survey was performed to schedule the date and hour for on-toone interviews, and select potential donors eligible for testing. They were tested for HIV, HBV, HCV, HTLV I and II, Chagas disease and syphilis, NAT for HIV, HBV y HCV, anti HLA antibodies and anti SARS-CoV-2 IgG antibodies. PCR for SARS-CoV-2 was performed in all donors with less than 28 days since last symptoms. After all these studies, apheresis was indicated for selected donors. Results/Findings: From 5008 inscriptions on the web site, 21.1% were deferred automatically at the web site level. A total of 1165 volunteers were interviewed in our institution, and, from them, 25.8% were excluded after the questionnaire (73%) or because of poor venous access (27%). From the 864 accepted and tested volunteers, 0.9%were deferred because of microbiological studies, 22.6% for less than 1:320 antibodies titers. From 465 women tested, 26.6% were excluded for the presence of anti HLA antibodies. Finally, 536 donors were able to proceed with apheresis. Conclusions: The 46% from total volunteers were finally able to proceed to apheresis in our institution. The cooperative effort between institutions allowed us to start working within four weeks since the first case was reported in our country, with 444 effective apheresis performed over the course of 16 weeks.

A chilean blood bank network for COVID-19 convalescent plasma apheresis

Background/Case Studies: During the coronavirus pandemic, where there is no known treatment, nor vaccine, convalescent plasma transfusion became an alterna-tive for patients who had a severe condition, or with risk factors that promoted serious disease. Study Design/Methods: The project was submitted to the ethics committee, for convalescent COVID-19 plasma administration in patients with severe criteria, without severity criteria but with risk factors, and for active cancer patients. The allowed criteria for convalescent plasma transfusion were IgG antiSars CoV2 antibody titers greater than 1:320 and negative serological and NAT tests for HIV, HBV, HCV, HTLV, Syphilis, and Chagas. All women were also tested for HLA, which was required to be negative. Each unit of plasma had 200cc and the patients were transfused with 2 units. Funds were provided by private institutions and public hospitals. Private clinics, military forces hospitals and blood centers were invited to participate in this network. A donor registration web page was created. The donor blood bank interview was standardized. The plasma apheresis process was standardized according to equipment, and the processing, storage, distribution, and management of apheresis was standardized in all centers. All traceability and adverse events related to transfusion were recorded according to national regulations. Results/Findings: A total of 31 institutions received convalescent plasma, of which 11 were public institutions, 17 private institutions, and 3 from military forces hospitals (1 public, and 1 private institution were exclusive for oncologic patients). Of these, 48% were in Santiago (capital city) and 52% outside of the capital (corresponding to 13 different cities) including 3500 kms from north to south inside of the Chilean territory. Eight institutions produced convalescent plasma, of which 88% were private, 12% of the military forces. Of these, 25% were outside the capital. Four centers used Terumo BCT equipment (4 Spectra OptiaR, and 2 Trima AccelR), 2 used Haemonetics (MCS+9000R), and 2 Fresenius Kabi equipment (Com.tecR). A total of 5008 voluntary donors were registered on the website, of whom 1400 donors were interviewed at all producing centers. A total of 594 apheresis was made from 463 donors;82% of patients donated one time and 18% donated 2 or more times. A total of 1540 plasmas were produced, and to date a total of 263 patients had been transfused and a total of 737 units had been delivered. Of these only 10% had an adverse reaction to mild transfusion (fever greater than 38.5°C), and only 2 (0.7%) serious adverse reaction. None of the transfused died due to the transfusion or a secondary complication derived from it. Conclusions: This is the largest study conducted in the country. This is the first time that a public-private network has been generated that covers different regions of the country. Safety is consistent with what is reported in the literature.