Impact of serological and PCR testing requirements on the selection of COVID‐19 convalescent plasma donors

Abstract

Background Convalescent plasma is undergoing randomized trials as a potential therapeutic option for COVID‐19 infection. Little empirical evidence exists regarding the determination of donor eligibility and experiences with donor selection. Study Design and Methods This prospective study was conducted at a tertiary care hospital in New York to select plasma donors for a randomized, double‐blind, controlled convalescent plasma trial. Clearance for donation required successful completion of an online questionnaire and an in‐person screening visit, which included (a) completion of a Donor Health Questionnaire (DHQ), (b) Immunoglobulin G (IgG) antibody testing using an immunochromatographic anti‐ severe acute respiratory coronavirus 2 (SARS‐CoV‐2) test, (c) Polymerase chain reaction (PCR) testing if <28 days from symptom resolution, and (d) routine blood bank testing. Results After receiving 3093 online questionnaires, 521 individuals presented for in‐person screening visits, with 40.1% (n = 209) fully qualifying. Subjects (n = 312) failed to progress due to the following reasons: disqualifying answer from DHQ (n = 30, 9.6%), insufficient antibodies (n = 198, 63.5%), persistent positive PCR tests (n = 14, 4.5%), and blood donation testing labs (n = 70, 22.4%). Importantly, 24.6% and 11.1% of potential donors who reported having PCR‐diagnosed infection had low or undetectable SARS‐CoV‐2 antibody levels, respectively. Surprisingly, 62.9% (56/89) of subjects had positive PCR tests 14–27 days after symptom resolution, with 13 individuals continuing to be PCR positive after 27 days. Conclusion It is feasible for a single site to fully qualify a large number of convalescent plasma donors in a short period of time. Among otherwise qualified convalescent plasma donors, we found high rates of low or undetectable antibody levels and many individuals with persistently positive PCR tests.

Diagnostic Approaches For COVID-19: Lessons Learned and the Path Forward

“…This type of test is important to identify the potential convalescent plasma donors and to monitor the subject’s immune status over time. 43 − 45 Many rapid serological tests were quickly developed; 40 − 42 , 46 however, they do not provide information on active infection as the body takes several weeks to develop a detectable level of antibodies following the infection. 47 Table 2 summarizes the differences between the three main testing methods currently employed in the diagnosis of COVID-19.…”

“…The second category is the antigen tests that involve the detection of the virus proteins either from saliva, nasal, or nasopharyngeal swabs, or even in the blood. − The third category is the serological or immunological assay which is an indirect method of detecting the virus as the test looks for developed antibodies as a response to the infection rather than detecting the virus itself. − Serological tests detect the presence of antibodies in the blood when the body is responding to the viral infection. This type of test is important to identify the potential convalescent plasma donors and to monitor the subject’s immune status over time. − Many rapid serological tests were quickly developed; − , however, they do not provide information on active infection as the body takes several weeks to develop a detectable level of antibodies following the infection Table summarizes the differences between the three main testing methods currently employed in the diagnosis of COVID-19.…”

Passive Immunity Should and Will Work for COVID-19 for Some Patients

“…The development of convalescent donor plasma programs for COVID-19 occurred in short order [199][200][201]. A proportion of proven-infected donors may not have measurable antibody, and some asymptomatic infections may yet be associated with significant seropositivity [200,201]. EIA or neutralizing antibody standards were provisionally set for donor units [103].…”

“…At screening, however, there is a considerable range of antibody levels [79,80,200,[203][204][205]. There may be some nonserological reasons why prospective donors may be rejected [201].…”

“…At screening, however, there is a considerable range of antibody levels [ 79 , 80 , 200 , 203 – 205 ]. There may be some non-serological reasons why prospective donors may be rejected [ 201 ]. The collection of convalescent plasma from donor systems should exclude infectiousness, given the detection by some of viral RNA in blood.…”