Paula Saa1*, PhD; Bryan Spencer2, PhD, MPH; Ed Notari1, MPH; Galen Conti1, MPH
1American Red Cross Scientific Affairs, Rockville, MD; 2American Red Cross Scientific Affairs, Boston, MA; *Corresponding author
After a series of virtual meetings, we were all very excited to reconnect in person at the 2023 AABB annual meeting in Nashville, TN, where the American Red Cross Scientific Affairs group contributed four oral presentations, including one plenary presentation; two posters; and several co-authorships on posters and oral abstracts presented by our long-standing collaborators. The oral presentations, summarized below, discussed large multicenter studies focusing on SARS-CoV-2 surveillance and the impact of donor policy changes on the safety of the United States (US) blood supply.
Dr. Spencer’s talk focused on the challenges of incident case surveillance of SARS-CoV-2 infections and strategies to overcome these limitations. Public health surveillance is challenged by unreported cases related to increased use of rapid antigen tests conducted at home and the inability of serological assays to distinguish primary infections from reinfections. Cross-sectional serological surveys of anti-spike (S) and anti-nucleocapsid (N) antibodies are unable to provide estimates of reinfections due to increasing rates of prior infection, which induces anti-S and anti-N, and vaccination, which induces anti-S. To overcome these challenges, the investigators sought to identify incident swab-confirmed infections using online surveys of a large prospective cohort of US blood donors and to distinguish between primary infections and reinfections. Among 66,274 donors completing >2 surveys, 23,963 primary infections and 2,695 reinfections were reported cumulatively through the 4th quarter of 2022 (2022-Q4). The proportion of infections that were reinfections increased from <1% in 2020 to 19% in 2022-Q4.1
Dr. Saa presented a study of pre-symptomatic blood donors with pre-existing COVID-19 immunity. The objectives were to investigate if different variants of SARS-CoV-2 differed in their propensity to cause RNAemia and whether COVID-19 vaccination and/or prior SARS-CoV-2 infection protected from development of RNAemia and COVID-19 symptoms. The data collected showed that SARS-CoV-2 RNA was detected in 8% of tested units and that the rates of RNAemia did not change significantly during the delta and omicron variant eras. RNAemic donors developed symptoms sooner than non-RNAemic donors and reported their infection earlier, which allowed timely retrieval of their RNAemic donations. Dr. Saa also provided evidence of the protective effects of vaccination and prior SARS-CoV-2 infection on development of presymptomatic RNAemia and symptomatic disease.2
Ed Notari’s talk provided contemporary information and results covering how the Transfusion Transmissible Infections Monitoring System (TTIMS) program–and in particular the donor data coordinating center (DDCC) of TTIMS, led by Scientific Affairs–monitors US blood safety and how this program is geared to evaluate the impact that donor policy changes may have on the safety of the blood supply. Mr. Notari described the methods used and findings on the prevalence, incidence, and residual risks of transfusion-transmitted HIV, HBV, HCV and syphilis. His talk focused on tools utilized to calculate HIV incidence in first-time donors including novel approaches to residual risk estimation, behavioral risk factors, assessment of antiretroviral use in blood donors, and biomarker monitoring.
Galen Conti presented TTIMS syphilis prevalence and incidence data based on donor antibody results from 2020 to 2022. Syphilis prevalence estimates were calculated for consensus positive (CP) infections (which include screen reactive, confirmed-positive infections based on total antibodies) and active infections (AI) (a subset of CPs that are also rapid plasma reagin (RPR) positive). Importantly, syphilis is an indicator for other sexually transmitted infections. This dataset sheds light on the status of syphilis infections in the US blood donor population. Mr. Conti’s presentation was highlighted in the AABB23 Newsfeed.3
1. Spencer B, Akinseye A, Grebe E, et al. OA5‐AM23‐ST‐23 | SARS‐CoV‐2 Primary Infections and Reinfections Among a Nationwide Prospective Blood Donor Cohort. Transfusion. 2023;63(S5):35A-36A.
2. Saa P, Fink R, Di Germanio C, et al. OA3‐AM23‐MN‐23 | Reduced Frequency of SARS‐CoV‐2 Symptom and RNAemia Development in Pre‐Symptomatic Blood Donors with Pre‐Existing Immunity. Transfusion. 2023;63(S5):63A-64A.
3. Conti G, Notari E, Dodd R, et al. PL4‐AM23‐SN‐30 | Syphilis Seroprevalence and Incidence in Blood Donors from 2020 to 2022, on Behalf of the US TTIMS Program. Transfusion. 2023;63(S5):12A-13A.