No abstract

In March 2020, COVID-19 was declared a pandemic by the WHO. Since then, efforts have been made to increase our knowledge of the disease. The convalescent plasma (CP) donation involves a series of criteria for donor eligibility, such as pre-donation and serological tests. Currently, the antibody response against SARS-CoV-2 remains poorly understood and the usefulness of serological tests is unclear (Long, et al. Nature Medicine, 2020). Based on donor eligibility, one can better assess the antibody response to SARS-CoV-2 from post-infection candidates. This is an observational, prospective study, without intervention. From 06/26/2020 to 07/31/2020, serological data of candidates for CP donation were collected. Recovered COVID-19 patients who had been previously tested were interviewed. RT-PCR and serological test (chemiluminescence immunoassays) for SARS-CoV-2 were carried out to verify their eligibility for CP collection. The data were related to the time of the onset of symptoms and the collection of the material. Subjects with non-detectable RT-PCR and reagent IgG were considered eligible. Reference values were IgM > 1.2 AU/mL and IgG > 1.4 AU/mL. The characteristics of the candidates are summarized in Table 1. Of 234 interviewed subjects, 70 were screened for pre-collection tests, 49 were male. The average age was 36 (20 - 57). After serological screening, 44/70 (62.8%) were considered eligible for CP donation. The reasons for ineligibility were: 17/70 (24.3%) non-reagent IgG, 4/70 (5.7%) with detectable RT-PCR and 5/70 (7.1%) due to reasons in clinical screening. The median between the onset of symptoms and the serology sample collection was 32.5 (21 - 77) days, (IQR 28.75 to 37.25). Those who were more likely to be eligible to donate were the subjects who had a longer time interval between the symptoms onset and the sample collection (p <0.012). Although viral clearance in the upper airways is expected from the 10th day of symptom onset, only 50% of patients will have an undetectable test (Özçürümez, et al. J Allergy Clin Immunol. 2020). In our sample, 5.7% (4/70) of the subjects had detectable RT-PCR, which can represent residual viral genome and not active infection. We observed that 20% of the subjects samples were non-reagent. Those who were tested up to the 21st of the onset of symptoms might not have had seroconversion yet. For those tested after the 28th day, we can infer that the antibodies had already been cleared. Some authors state that patients who had mild infections may react with less antibodies (Özçürümez, et al. J Allergy Clin Immunol. 2020), which could explain this fact. Likewise, it was not possible to relate serological titers to the severity of the disease, as this was not one of the selection criteria.In 40/70 donors (57.2%) IgM remained above 1.2 AU / mL after the 21st day of symptom onset. Interestingly, 2 of these had only reagent IgM after the 36th day of symptom onset. Most subjects who had reagent IgM after the 21st of symptoms also had reagent IgG. We inferred that they were in a vigorous convalescence phase. In addition, 75.7% of the subjects presented reagent IgG regardless of the date of onset of symptoms. Most of them had both reagent IgM and IgG. Only one donor's (1.4%) IgM and IgG were non-reagent 21 days after the onset of symptoms. As we did not collect serial samples, we could not verify the average amount of days for seroconversion to take place. Some authors recommend that the single collection should occur at least 21 days after the onset of symptoms, so seroconversion is observed (Deeks, et al., Cochrane Database Syst Rev. 2020). In our sample, 4 donors (5%) collected the samples on the 21st day after the symptom onset. Of these, 3 had seroconversion, 2 with IgM and IgG, 1 with IgG and 1 with reagent IgM. The values suggest that the subjects who could donate CP were those that presented a longer time interval between the onset of symptoms and the blood sample collection, in comparison to those who could not (p=0,012 and 0,409, respectively). The median of days between symptom onset and serology testing was also higher in the non-eligible group. Besides, the eligible group had a higher average concentration of IgM and IgG compared to the non-eligible one. In conclusion, regarding the serological criteria, about 25% of the studied population could not donate CP. Although a single serology sample collection after the 21st day of symptom onset is recommended, only 1 candidate did not show seroconversion. Disclosures No relevant conflicts of interest to declare.

In Brazil, until the 1980s, the context of blood as transfusion therapy was marked by paid donations. Thus, self-interest has surpassed solidarity as a motivator to donate. Recruiting donors involves advising the population due to the difficulties related to the myths around donation. With the COVID-19 pandemic, recruiting convalescent plasma (CP) donors has been a hard. This is an observational, prospective and non-interventionist study carried out in a hemotherapy unit of the Unified Health System, in central-western Brazil. Data collection was carried out from 06/19/2020 to 07/31/2020. The subjects were contacted by the Recruitment and Collection (CR) sector, through an active search, using lists of patients previously diagnosed with COVID-19. The study was also published on social and traditional networks, which resulted in self-reference. Convalescent COVID-19 patients tested, of both genders, aged between 18 and 60 years, weight over 60 kg, without symptoms for more than 14 days, and nulliparous donors were invited to the study. Those who met the criteria were scheduled for clinical and serological screening. The subjects eligible for donation, with IgG reagent, signed the Free and Informed Consent Form. Individuals with positive RT-PCR and / or non-reactive IgG were excluded. During the study period, RC made 308 and received 1,797 calls (2,105 contacts), generating 242 (11.5%) screening appointments, 173 (8.2%) of which resulted from self-referral and 69 (3.2%) from active search. Of these, 131 (6.2%) subjects attended the appointment. After clinical screening, 37 (28.25%) subjects were ineligible, 37 (28.25%) after serological tests and 57 (43.5%) were eligible for donation. The ineligibility causes in clinical and serological screening are described in table 1. Many countries face difficulties in meeting the demand for blood and its components during the pandemic (Barone & DeSimone. Transfusion, 2020), especially in those where blood commercialization is prohibited, as in Brazil. The purpose of recruiting donors is to make blood donation habitual to Brazilians, as it occurs in developed countries. Figure 2 shows self-referral rates after dissemination in traditional media. The ads focused on the donor's ability to save lives by encouraging altruism (Ronse, et al. 2018).On the other hand, despite attracting more people, most were not eligible for donation, demonstrating a great capacity to raise awarenessamong the population, but it was necessary to improve criterias and demonstrate them clearly for the likely donor. Of the 26 donors, 22 (84.6%) are older than 29. For these, awareness-raising occurred mainly through the television media 9(34.6%) and 5(19.3%) through personal contact. In the youngest 4(15.4%), the stimulus was social networks (Sümnig, et al. Transfusion, 2018). Marketing was important for recruitment. As blood donation is not usual for most brazilians, it is essential to plan, develop, evaluate strategies, enabling new forms of collection. Another difficulty encountered was the logistics for this donation type. As the donor is convalescent, the recruitment, screening, and collection was restricted to a physical space, isolated from conventional donos (Bloch, et al. J Clin Invest. 2020). In conclusion, the COVID-19 pandemic has become a public health challenge worldwide. Many recovered patients could donate CP. However, it is necessary to define the ideal requirements for donor selection to ensure the therapeutic viability and efficacy of PC transfusion. Blood collection teams need to strengthen strategies to inform the population about blood donation needs. The information available in the traditional and digital media about the donation process can increase the donation rate and guarantee a safe blood component. Strategies such as a greater number of insertions in social networks with well-defined criteria for donating plasma from a convalescent donor, clarification of exclusion criteria in the means of greater reach, creation of easily accessible channels to the donor (registrations, central doubts),in addition to stratifying by age group and proposing different dissemination strategies and thanksgiving for the donation, forming a network of donations. The combined efforts of these actions will contribute with expert advice and experience, technical guidance and additional support to potentially save more lives. Disclosures No relevant conflicts of interest to declare.