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BackgroundA national serosurvey of U.S. blood donors conducted in partnership with the Centers for Disease Control and Prevention (CDC) was initiated to estimate the prevalence of SARS-CoV-2 infections and vaccinations.MethodsBeginning in July 2020, the Nationwide Blood Donor Seroprevalence Study collaborated with multiple blood collection organizations, testing labs, and leadership from government partners to capture, test, and analyze approximately 150,000 blood donation specimens per month in a repeated, cross-sectional seroprevalence survey.ResultsA CDC website (https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence) provided stratified, population-level results to public health professionals and the general public.DiscussionThe study adapted operations as the pandemic evolved, changing specimen flow and testing algorithms, and collecting additional data elements in response to changing policies on universal blood donation screening and administration of SARS-CoV-2 spike-based vaccines. The national serosurvey demonstrated the utility of serosurveillance testing of residual blood donations and highlighted the role of the blood collection industry in public-private partnerships during a public health emergency.

BACKGROUND Understanding the effect of delayed processing of whole blood on plasma ferritin will inform the feasibility of both routine ferritin testing in donors and clinical research study design. STUDY DESIGN AND METHODS Whole blood tubes drawn from 16 donors were held at 4°C and centrifuged at 24-hour intervals to assess plasma ferritin concentration up to 5 days after draw. Intraindividual variation over time was measured in 21 healthy donors in blood samples collected weekly for 4 weeks and then at 12 weeks. RESULTS No significant variation in plasma ferritin concentration was observed in blood stored at 4°C for up to 5 days after draw (p = 0.32). The estimated loss of 4.75% ferritin over 5 days was within the reported 5% variation of the assay. Moderate intraindividual variation occurs over time in both sexes, with variability increasing with the mean. No difference was detected between men and women in the regression of standard deviation on mean ferritin (p = 0.43). CONCLUSIONS Ferritin is stable in whole blood up to 5 days, demonstrating operational feasibility of its use in monitoring donor iron stores. Moderate fluctuations over time occur, but ferritin measurements are sufficiently reliable to determine donor iron status on the day of donation.

BACKGROUND Babesia microti is the foremost infectious risk to the US blood supply for which a Food and Drug Administration (FDA)-licensed test is unavailable for donation screening. Characterization of the antibody response to B. microti and correlation with parasitemia is necessary to guide screening and donor management policies. STUDY DESIGN AND METHODS During an FDA licensure trial, blood donors were prospectively screened (July-November 2013) using a B. microti-specific antibody enzyme immunoassay (EIA, Immunetics) in highly endemic (New York [NY]; n = 13,688), moderately endemic (Minnesota [MN]; n = 4583), and nonendemic (New Mexico [NM]; n = 8451) regions. Blood donors with repeat-reactive (RR) results participated in a 12-month prospective cohort study using B. microti EIA, immunofluorescent assay, polymerase chain reaction (PCR), blood smear, and clinical questionnaire. RESULTS Thirty-seven (61.67%; 24 NY, seven MN, six NM) of 60 eligible RR donors enrolled in the study; 20 of 37 (54%) completed the 12-month follow-up visit of which 15 (75%) were still seroreactive. Nine PCR-positive donors were identified during index screening; five participated in the follow-up study, three were PCR positive at 6 months, and two remained positive at final follow-up (378 and 404 days). Most RR donors displayed low-level seroreactivity that was either stable or waning during follow-up. The level and pattern of reactivity correlated poorly with PCR positivity. CONCLUSION The findings indicate prolonged seropositivity in blood donors. Although rare, asymptomatic, persistent PCR positivity supports the current policy of indefinite deferral for donors with a history of babesiosis or positive test results. Repeat testing by PCR and serology will be necessary if reinstatement is to be considered.

Babesiosis is a malaria-like illness caused by infection by members of the genus Babesia, a group of tick-borne intraerythrocytic protozoan parasites.1 Babesia microti is responsible for the overwhelming majority of human Babesia infections reported in the United States, where it is endemic in parts of the Northeast and upper Midwest. The parasite is primarily transmitted to humans through exposure to Ixodes scapularis (“deer ticks”) in endemic areas. However, B. microti is also readily transmissible by blood transfusion, and transfusion-transmitted babesiosis (TTB) is increasingly recognized as posing a risk to the blood supply.2,3 While B. microti infection results in asymptomatic or mild clinical findings in most immunocompetent hosts, infection in selected patient subsets, notably those who are immunosuppressed, asplenic, and/or at extremes of age, may lead to severe or even fatal disease.3,4 Overrepresentation of transfusion recipients among these high-risk groups accounts for the relatively high mortality ascribed to TTB.4,5 Currently, the only mandated strategy for TTB mitigation in use is a question regarding history of babesiosis posed directly to the potential donor before donation. The failure of this approach is evidenced by more than 150 cases of TTB that have been reported since 1979 with at least 12 fatalities since 2005.3 Despite being acknowledged as the foremost infectious risk to the US blood supply at present,5 there are as yet no validated, US Food and Drug Administration (FDA)-approved and commercially available tests for B. microti screening in blood donors. We report the development of a high-throughput enzyme immunoassay (EIA) that detects antibodies to B. microti, and B. microti seroreactivity was determined with this EIA in samples from New York Blood Center (NYBC) blood donors collected over a 4-month period in 2012. This pilot study was used to optimize the cutoff of the EIA and to validate the EIA and confirmatory algorithms before an FDA licensure trial launched in 2013.

BACKGROUND: In the United States, blood products are tested for infectious diseases including human T-lymphotropic virus (HTLV)-I/II. Positive results of maternal blood samples at the time of cord blood (CB) donation must be reported to mother and physician. Tests for HTLV have a high false-positive rate. This is problematic because there is no prenatal testing of the mother. STUDY DESIGN AND METHODS: This study involves 119,769 maternal blood samples at time of CB donation and evaluates positive results for HTLV in screening tests, supplemental immunoassays, and nucleic acid tests (NATs). Infectious disease markers (IDMs) and maternal health histories of HTLV-positive and -negative mothers were compared. RESULTS: Of 119,769 mothers donating CB, 545 tested positive with the screening test, 33 were positive with the supplemental tests, and two were positive with NAT. When indeterminate results were excluded from the supplemental test only six were positive. Eight of 34 mothers with positive or indeterminate supplemental test results had received intravenous immunoglobulin. There were no significant differences between HTLV-positive and -negative mothers with regard to the incidence of other IDMs. CONCLUSIONS: Testing maternal blood for HTLV is problematic for CB banks, obstetricians, and mothers because of the high false-positive rate. CB banks need rapid turnaround time and supplemental testing. If results on the latter are positive the obstetrician should be notified, educated, do follow-up testing, and counseling. Indeterminate results on supplemental tests are most likely false positives. We recommend that mothers with positive or indeterminate supplemental test results have follow-up NAT.

BACKGROUND The tick-borne pathogen Babesia microti has become recognized as the leading infectious risk associated with blood transfusion in the United States, yet no Food and Drug Administration–licensed screening tests are currently available to mitigate this risk. The aim of this study was to evaluate the performance of an investigational enzyme immunoassay (EIA) for B. microti as a screening test applied to endemic and nonendemic blood donor populations. STUDY DESIGN AND METHODS The study aimed to test 20,000 blood donors from areas of the United States considered endemic for B. microti and 10,000 donors from a nonendemic area with the investigational B. microti EIA. Repeat-reactive samples were retested by polymerase chain reaction (PCR), blood smear, immunofluorescent assay (IFA), and immunoblot assay. In parallel, serum samples from symptomatic patients with confirmed babesiosis were tested by EIA, IFA, and immunoblot assays. RESULTS A total of 38 of 13,757 (0.28%) of the donors from New York, 7 of 4583 (0.15%) from Minnesota, and 11 of 8363 (0.13%) from New Mexico were found repeat reactive by EIA. Nine of the 56 EIA repeat-reactive donors (eight from New York and one from Minnesota) were positive by PCR. The specificity of the assay in a nonendemic population was 99.93%. Among IFA-positive clinical babesiosis patients, the sensitivity of the assay was 91.1%. CONCLUSION The B. microti EIA detected PCR-positive, potentially infectious blood donors in an endemic population and exhibited high specificity among uninfected and unexposed individuals. The EIA promises to provide an effective tool for blood donor screening for B. microti in a format amenable to high-throughput and cost-effective screening.

Serologic screening for human T-cell leukemia virus type I (HTLV-I) infection was begun in US blood banks with the licensure of enzyme- linked immunosorbent assays (ELISA) in December 1988. We examined the donation histories of the first 60 Western blot (WB)-confirmed HTLV- I/II positive donors to one blood center and found 8 had made 16 previous donations that scored negative on the screening ELISA. All 16 donations had ELISA absorbance below the cutoff for a positive assay, but still well above that of the average donation (17.6% +/- 5.7% of the cutoff). In a more extensive study, 17 donations from a total of 61,752 at six blood centers were both ELISA-positive and WB-positive for HTLV-I (4) or HTLV-II (13), and 218 samples had ELISA absorbance greater than 50% of the ELISA cutoff. One hundred seventy-eight of the 218 were tested further by WB and 11 were found positive. All 11 positives were confirmed by polymerase chain reaction; 10 had HTLV-II and 1 had HTLV-I. Thus, the HTLV-I-based screening ELISA missed at least 10 of 23, or 43% (95% confidence interval, 23% to 66%), of HTLV- II infections, compared with 1 of 5, or 20%, of HTLV-I infections.