Optimization and Local Cost-Effectiveness of Nasopharyngeal Carcinoma Screening Strategies in Southern China: Secondary Analysis of the Guangdong Randomized Trial.

BACKGROUND: Screening with anti-Epstein-Barr Virus (EBV) serology and endoscopy decreased nasopharyngeal carcinoma (NPC) mortality in Guangdong in a randomized trial. We conducted a secondary analysis of this trial using local incidence and cost data to optimize screening programs, hypothesizing that screening could be cost-effective in southern China. METHODS: Screening costs and life-years after NPC diagnosis were obtained from the Guangdong trial's intent-to-screen population (men and women age 30-69). Seropositive subjects were rescreened annually for five years. Thereafter, we evaluated 12 screening strategies in Guangdong and Guangxi using a validated model. Strategies used combinations of serology, nasopharyngeal swab PCR (NP PCR), endoscopy, and MRI from trial sub-cohorts. Incidence data and costs were obtained from local cancer registries and the provincial healthcare system. RESULTS: In the intent-to-screen population, screening with serology and endoscopy was cost-effective (¥42,366/life-year, 0.52 GDP per-capita). Screening for 5-15 years between ages 35-59 met a willingness-to-pay threshold of 1.5 GDP/QALY in all modeled populations. Despite doubling costs, adding MRI could be cost-effective via improved sensitivity. NP PCR triage reduced endoscopy/MRI referrals by 37%. One lifetime screen could reduce NPC mortality by pproximately 20%. CONCLUSIONS: EBV-based serologic screening for NPC is likely to be cost-effective in southern China. Among seropositive subjects, the preferred strategies use endoscopy alone or selective endoscopy triaged by MRI with or without NP PCR. These data may aid the design of screening programs in this region. IMPACT: These findings support population-based screening in southern China by defining the target population, cost effectiveness, and optimized screening approach.

PIP4K2C inhibition reverses autophagic flux impairment induced by SARS-CoV-2.

In search for broad-spectrum antivirals, we discovered a small molecule inhibitor, RMC-113, that potently suppresses the replication of multiple RNA viruses including SARS-CoV-2 in human lung organoids. We demonstrated selective dual inhibition of the lipid kinases PIP4K2C and PIKfyve by RMC-113 and target engagement by its clickable analog. Advanced lipidomics revealed alteration of SARS-CoV-2-induced phosphoinositide signature by RMC-113 and linked its antiviral effect with functional PIP4K2C and PIKfyve inhibition. We discovered PIP4K2C's roles in SARS-CoV-2 entry, RNA replication, and assembly/egress, validating it as a druggable antiviral target. Integrating proteomics, single-cell transcriptomics, and functional assays revealed that PIP4K2C binds SARS-CoV-2 nonstructural protein 6 and regulates virus-induced impairment of autophagic flux. Reversing this autophagic flux impairment is a mechanism of antiviral action of RMC-113. These findings reveal virus-induced autophagy regulation via PIP4K2C, an understudied kinase, and propose dual inhibition of PIP4K2C and PIKfyve as a candidate strategy to combat emerging viruses.

Determination of the cycle threshold value of the Xpert Xpress SARS-CoV-2/Flu/RSV test that corresponds to the presence of infectious SARS-CoV-2 in anterior nasal swabs.

Despite having high analytical sensitivities and specificities, qualitative SARS-CoV-2 nucleic acid amplification tests (NAATs) cannot distinguish infectious from non-infectious virus in clinical samples. In this study, we determined the highest cycle threshold (Ct) value of the SARS-CoV-2 targets in the Xpert Xpress SARS-CoV-2/Flu/RSV (Xpert 4plex) test that corresponded to the presence of detectable infectious SARS-CoV-2 in anterior nasal swab samples. A total of 111 individuals with nasopharyngeal swab specimens that were initially tested by the Xpert Xpress SARS-CoV-2 test were enrolled. A healthcare worker subsequently collected anterior nasal swabs from all SARS-CoV-2-positive individuals, and those specimens were tested by the Xpert 4plex test, viral culture, and laboratory-developed assays for SARS-CoV-2 replication intermediates. SARS-CoV-2 Ct values from the Xpert 4plex test were correlated with data from culture and replication intermediate testing to determine the Xpert 4plex assay Ct value that corresponded to the presence of infectious virus. Ninety-eight of the 111 (88.3%) individuals initially tested positive by the Xpert Xpress SARS-CoV-2 test. An anterior nasal swab specimen collected from positive individuals a median of 2 days later (range, 0-9 days) tested positive for SARS-CoV-2 by the Xpert 4plex test in 39.8% (39/98) of cases. Of these samples, 13 (33.3%) were considered to contain infectious virus based on the presence of cultivable virus and replication intermediates, and the highest Ct value observed for the Xpert 4plex test in these instances was 26.3. Specimens that yielded Ct values of ≤26.3 when tested by the Xpert 4plex test had a likelihood of containing infectious SARS-CoV-2; however, no infectious virus was detected in specimens with higher Ct values.IMPORTANCEUnderstanding the correlation between real-time PCR test results and the presence of infectious SARS-CoV-2 may be useful for informing patient management and workforce return-to-work or -duty. Further studies in different patient populations are needed to correlate Ct values or other biomarkers of viral replication along with the presence of infectious virus in clinical samples.

XBB.1.5 monovalent booster improves antibody binding and neutralization against emerging SARS-CoV-2 Omicron variants.

The rapid emergence of divergent SARS-CoV-2 variants has led to an update of the COVID-19 booster vaccine to a monovalent version containing the XBB.1.5 spike. To determine the neutralization breadth following booster immunization, we collected blood samples from 24 individuals pre- and post-XBB.1.5 mRNA booster vaccination (∼1 month). The XBB.1.5 booster improved both neutralizing activity against the ancestral SARS-CoV-2 strain (WA1) and the circulating Omicron variants, including EG.5.1, HK.3, HV.1, XBB.1.5 and JN.1. Relative to the pre-boost titers, the XBB.1.5 monovalent booster induced greater total IgG and IgG subclass binding, particular IgG4, to the XBB.1.5 spike as compared to the WA1 spike. We evaluated antigen-specific memory B cells (MBCs) using either spike or receptor binding domain (RBD) probes and found that the monovalent booster largely increases non-RBD cross-reactive MBCs. These data suggest that the XBB.1.5 monovalent booster induces cross-reactive antibodies that neutralize XBB.1.5 and related Omicron variants.

Characterization of Dengue Virus 4 Cases in Paraguay, 2019-2020.

In 2019-2020, dengue virus (DENV) type 4 emerged to cause the largest DENV outbreak in Paraguay's history. This study sought to characterize dengue relative to other acute illness cases and use phylogenetic analysis to understand the outbreak's origin. Individuals with an acute illness (≤7 days) were enrolled and tested for DENV nonstructural protein 1 (NS1) and viral RNA by real-time RT-PCR. Near-complete genome sequences were obtained from 62 DENV-4 positive samples. From January 2019 to March 2020, 799 participants were enrolled: 253 dengue (14 severe dengue, 5.5%) and 546 other acute illness cases. DENV-4 was detected in 238 dengue cases (94.1%). NS1 detection by rapid test was 52.5% sensitive (53/101) and 96.5% specific (387/401) for dengue compared to rRT-PCR. DENV-4 sequences were grouped into two clades within genotype II. No clustering was observed based on dengue severity, location, or date. Sequences obtained here were most closely related to 2018 DENV-4 sequences from Paraguay, followed by a 2013 sequence from southern Brazil. DENV-4 can result in large outbreaks, including severe cases, and is poorly detected with available rapid diagnostics. Outbreak strains seem to have been circulating in Paraguay and Brazil prior to 2018, highlighting the importance of sustained DENV genomic surveillance.

Disease diagnostics using machine learning of immune receptors.

Clinical diagnosis typically incorporates physical examination, patient history, and various laboratory tests and imaging studies, but makes limited use of the human system's own record of antigen exposures encoded by receptors on B cells and T cells. We analyzed immune receptor datasets from 593 individuals to develop MAchine Learning for Immunological Diagnosis (Mal-ID) , an interpretive framework to screen for multiple illnesses simultaneously or precisely test for one condition. This approach detects specific infections, autoimmune disorders, vaccine responses, and disease severity differences. Human-interpretable features of the model recapitulate known immune responses to SARS-CoV-2, Influenza, and HIV, highlight antigen-specific receptors, and reveal distinct characteristics of Systemic Lupus Erythematosus and Type-1 Diabetes autoreactivity. This analysis framework has broad potential for scientific and clinical interpretation of human immune responses.

Low infectivity among asymptomatic patients with a positive severe acute respiratory coronavirus virus 2 (SARS-CoV-2) admission test at a tertiary care center, 2020-2022.

We used a strand-specific RT-qPCR to evaluate viral replication as a surrogate for infectiousness among 242 asymptomatic inpatients with a positive severe acute respiratory coronavirus virus 2 (SARS-CoV-2) admission test. Only 21 patients (9%) had detectable SARS-CoV-2 minus-strand RNA. Because most patients were found to be noninfectious, our findings support the suspension of asymptomatic admission testing.

BA.5 bivalent booster vaccination enhances neutralization of XBB.1.5, XBB.1.16 and XBB.1.9 variants in patients with lung cancer.

This study reports that most patients with NSCLC had a significant increase in the nAb response to the currently circulating Omicron variants after bivalent booster vaccination and had Ab titers comparable to healthy participants. Interestingly, though the durability of the nAb response persisted in most of the healthy participants, patients with NSCLC had significantly reduced nAb titers after 4-6 months of vaccination. Our data highlight the importance of COVID-19 bivalent booster vaccination as the standard of care for patients with NSCLC given the evolution of new variants of concern.

Assessment of an automated Cytomegalovirus nucleic acid amplification test using clinical plasma, bronchoalveolar lavage, and tissue specimens.

BACKGROUND: Cytomegalovirus (CMV) causes significant morbidity and mortality in immunocompromised patients, particularly transplant recipients. Quantitation of CMV DNA in peripheral blood is used to monitor prophylactic and pre-emptive approaches to prevent CMV disease, whereas CMV DNA testing of non-plasma specimens may aid in the diagnosis of end-organ disease. METHODS: The analytical performance of the FDA-approved Aptima CMV Quant Assay was evaluated using reference CMV (SeraCare) diluted in defibrinated human plasma, as well as negative bronchoalveolar lavage fluid and tissue. Agreement was determined using 100 clinical acid-citrate-dextrose (ACD) plasma specimens, 77 bronchoalveolar lavage (BAL) fluids, and 101 tissues previously tested using artus CMV qPCR. RESULTS: Aptima CMV lower limit of detection (LLOD) was 169 IU/mL for ACD plasma, 100 IU/mL for BAL, and 50 IU/mL for tissue. Positive percent agreement (PPA) was 100.0% (50/50; 95% CI: 92.9% - 100.0%) and negative percent agreement (NPA) was 94.0% (47/50; 95% CI: 83.5% - 98.8%) for ACD plasma. Bland-Altman analysis revealed a bias of 0.20 log10 IU/mL (Aptima - artus) with 95% limits of agreement of -0.53 to 0.93. For BAL fluids, PPA was 70.0% (14/20; 95% CI: 45.7% - 88.1%) and NPA was 82.4% (43/51; 95% CI: 69.1% - 91.6%). For tissues, PPA was 90.0% (45/50; 95% CI: 78.2% - 96.7%) and NPA was 94.0% (47/50; 95% CI: 83.5% - 98.8%). CONCLUSIONS: The Aptima CMV Quant Assay demonstrates high analytical sensitivity and good overall agreement using clinical plasma and tissue specimens.

Global and cell type-specific immunological hallmarks of severe dengue progression identified via a systems immunology approach.

Severe dengue (SD) is a major cause of morbidity and mortality. To define dengue virus (DENV) target cells and immunological hallmarks of SD progression in children's blood, we integrated two single-cell approaches capturing cellular and viral elements: virus-inclusive single-cell RNA sequencing (viscRNA-Seq 2) and targeted proteomics with secretome analysis and functional assays. Beyond myeloid cells, in natural infection, B cells harbor replicating DENV capable of infecting permissive cells. Alterations in cell type abundance, gene and protein expression and secretion as well as cell-cell communications point towards increased immune cell migration and inflammation in SD progressors. Concurrently, antigen-presenting cells from SD progressors demonstrate intact uptake yet impaired interferon response and antigen processing and presentation signatures, which are partly modulated by DENV. Increased activation, regulation and exhaustion of effector responses and expansion of HLA-DR-expressing adaptive-like NK cells also characterize SD progressors. These findings reveal DENV target cells in human blood and provide insight into SD pathogenesis beyond antibody-mediated enhancement.

Human immunodeficiency virus 1 5'-leader mutations in plasma viruses before and after the development of reverse transcriptase inhibitor-resistance mutations.

Human immunodeficiency virus 1 (HIV-1) reverse transcriptase (RT) initiation depends on interaction between viral 5'-leader RNA, RT and host tRNA3Lys. Therefore, we sought to identify co-evolutionary changes between the 5'-leader and RT in viruses developing RT-inhibitor resistance mutations. We sequenced 5'-leader positions 37-356 of paired plasma virus samples from 29 individuals developing the nucleoside RT inhibitor (NRTI)-resistance mutation M184V, 19 developing a non-nucleoside RT inhibitor (NNRTI)-resistance mutation and 32 untreated controls. 5'-Leader variants were defined as positions where ≥20 % of next-generation sequencing (NGS) reads differed from the HXB2 sequence. Emergent mutations were defined as nucleotides undergoing a ≥4-fold change in proportion between baseline and follow-up. Mixtures were defined as positions containing ≥2 nucleotides each present in ≥20 % of NGS reads. Among 80 baseline sequences, 87 positions (27.2 %) contained a variant; 52 contained a mixture. Position 201 was the only position more likely to develop a mutation in the M184V (9/29 vs 0/32; P=0.0006) or NNRTI-resistance (4/19 vs 0/32; P=0.02; Fisher's exact test) groups than the control group. Mixtures at positions 200 and 201 occurred in 45.0 and 28.8 %, respectively, of baseline samples. Because of the high proportion of mixtures at these positions, we analysed 5'-leader mixture frequencies in two additional datasets: five publications reporting 294 dideoxyterminator clonal GenBank sequences from 42 individuals and six National Center for Biotechnology Information (NCBI) BioProjects reporting NGS datasets from 295 individuals. These analyses demonstrated position 200 and 201 mixtures at proportions similar to those in our samples and at frequencies several times higher than at all other 5'-leader positions. Although we did not convincingly document co-evolutionary changes between RT and 5'-leader sequences, we identified a novel phenomenon, wherein positions 200 and 201 immediately downstream of the HIV-1 primer binding site exhibited an extraordinarily high likelihood of containing a nucleotide mixture. Possible explanations for the high mixture rates are that these positions are particularly error-prone or provide a viral fitness advantage.

Tools Needed to Support Same-day Diagnosis and Treatment of Current Hepatitis C Infection.

Current HCV prevention efforts and treatment rates must improve for the United States (U.S.) to achieve WHO global elimination targets by 2030[1]. The current multi-day diagnosis and treatment paradigm for hepatitis C (HCV) infection leads to significant loss in the cascade of care, resulting in far fewer patients receiving treatment with direct acting antiviral agents (DAAs) than those diagnosed with HCV infection [2,3]. To achieve HCV elimination, a paradigm shift in access to HCV treatment is needed from current multi-day testing and treatment algorithms to same day diagnosis and treatment. This shift will require new tools, such as FDA-approved, CLIA-waived point-of-care (POC) antigen or nucleic acid tests (NAT) for HCV and HBV and NAT for HIV that do not require venous blood. Such a shift will also require better utilization of existing resources, expanding access to HCV treatment through availability of onsite treatment, removal of payer barriers to approval, adoption of minimal monitoring approaches during treatment, expanded access to available POC tests, and available specialist referral networks for patients who fail initial therapy, have advanced liver fibrosis, or have co-incident HIV or HBV infection. A same-day diagnosis and treatment paradigm will substantially contribute to HCV elimination by improving treatment rates for those diagnosed with HCV infection and expanding access to treatment in settings where patients have brief encounters with healthcare.

Two cases of MPXV infection during pregnancy in heterosexual cisgender women without classic cutaneous lesions, Northern California, 2022.

As part of an epidemiologic survey, we screened remnant samples collected for STI testing for mpox virus. We identified two cases of presumed MPXV infection in pregnant, heterosexual cisgender women. Here, we describe their pregnancy and birth outcomes. Both patients required induction of labor and experienced labor complicated by chorioamnionitis.

Anticancer pan-ErbB inhibitors reduce inflammation and tissue injury and exert broad-spectrum antiviral effects.

Targeting host factors exploited by multiple viruses could offer broad-spectrum solutions for pandemic preparedness. Seventeen candidates targeting diverse functions emerged in a screen of 4,413 compounds for SARS-CoV-2 inhibitors. We demonstrated that lapatinib and other approved inhibitors of the ErbB family of receptor tyrosine kinases suppress replication of SARS-CoV-2, Venezuelan equine encephalitis virus (VEEV), and other emerging viruses with a high barrier to resistance. Lapatinib suppressed SARS-CoV-2 entry and later stages of the viral life cycle and showed synergistic effect with the direct-acting antiviral nirmatrelvir. We discovered that ErbB1, ErbB2, and ErbB4 bind SARS-CoV-2 S1 protein and regulate viral and ACE2 internalization, and they are required for VEEV infection. In human lung organoids, lapatinib protected from SARS-CoV-2-induced activation of ErbB-regulated pathways implicated in non-infectious lung injury, proinflammatory cytokine production, and epithelial barrier injury. Lapatinib suppressed VEEV replication, cytokine production, and disruption of blood-brain barrier integrity in microfluidics-based human neurovascular units, and reduced mortality in a lethal infection murine model. We validated lapatinib-mediated inhibition of ErbB activity as an important mechanism of antiviral action. These findings reveal regulation of viral replication, inflammation, and tissue injury via ErbBs and establish a proof of principle for a repurposed, ErbB-targeted approach to combat emerging viruses.

Evaluation of an automated system for the quantitation of human Herpesvirus-6 DNA from clinical specimens.

Background: Quantitation of human herpesvirus-6 (HHV-6) DNA in clinical specimens is important for the diagnosis and management of HHV-6-associated infection and reactivation in immunocompromised patients, particularly transplant recipients. Methods: The analytical performance of the Altona RealStar ASR HHV-6 qPCR on the semi-automated AltoStar AM16 system was assessed using HHV-6 reference material in plasma and cerebral spinal fluid (CSF). Qualitative and quantitative agreement was determined using 123 clinical EDTA plasma specimens tested using a laboratory-developed HHV-6 qPCR. Results: The 95% Lower Limit of Detection was 20 IU/mL [95% confidence interval (CI): 10 to 29] in plasma and 78 IU/mL (95% CI: 55 to 146) in CSF. The assay was linear from 7.0 to 2.0 log10 IU/mL in both matrices. Overall agreement of the RealStar ASR HHV-6 qPCR on the AltoStar AM16 with a laboratory-developed test was 95.9% (95% CI: 90.8 to 98.7). Passing-Bablok analysis of specimens quantifiable by both methods and at levels >1000 copies/mL revealed a regression line of Y = 1.00*X-0.20, with neither systematic (95% CI Y-intercept: -0.66 to 0.26) nor proportional (95% CI slope: 0.89 to 1.10) bias compared to the reference. Conclusions: The RealStar ASR HHV-6 qPCR on the AltoStar AM16 provides accurate quantitation for clinical monitoring of HHV-6 in immunocompromised hosts.

Identification and confirmation via in situ hybridization of Merkel cell polyomavirus in rare cases of posttransplant cutaneous T-cell lymphoma.

BACKGROUND: Viral infection is an oncogenic factor in many hematolymphoid malignancies. We sought to determine the diagnostic yield of aligning off-target reads incidentally obtained during targeted hematolymphoid next-generation sequencing to a large database of viral genomes to screen for viral sequences within tumor specimens. METHODS: Alignment of off-target reads to viral genomes was performed using magicBLAST. Localization of Merkel cell polyomavirus (MCPyV) RNA was confirmed by RNAScope in situ hybridization. Integration analysis was performed using Virus-Clip. RESULTS: Four cases of post-cardiac-transplant folliculotropic mycosis fungoides (fMF) and one case of peripheral T-cell lymphoma (PTCL) were positive in off-target reads for MCPyV DNA. Two of the four cases of posttransplant fMF and the case of PTCL showed localization of MCPyV RNA to malignant lymphocytes, whereas the remaining two cases of posttransplant fMF showed MCPyV RNA in keratinocytes. CONCLUSIONS: Our findings raise the question of whether MCPyV may play a role in rare cases of T-lymphoproliferative disorders, particularly in the skin and in the heavily immunosuppressed posttransplant setting.

Rapid genetic screening with high quality factor metasurfaces.

Genetic analysis methods are foundational to advancing personalized medicine, accelerating disease diagnostics, and monitoring the health of organisms and ecosystems. Current nucleic acid technologies such as polymerase chain reaction (PCR) and next-generation sequencing (NGS) rely on sample amplification and can suffer from inhibition. Here, we introduce a label-free genetic screening platform based on high quality (high-Q) factor silicon nanoantennas functionalized with nucleic acid fragments. Each high-Q nanoantenna exhibits average resonant quality factors of 2,200 in physiological buffer. We quantitatively detect two gene fragments, SARS-CoV-2 envelope (E) and open reading frame 1b (ORF1b), with high-specificity via DNA hybridization. We also demonstrate femtomolar sensitivity in buffer and nanomolar sensitivity in spiked nasopharyngeal eluates within 5 minutes. Nanoantennas are patterned at densities of 160,000 devices per cm2, enabling future work on highly-multiplexed detection. Combined with advances in complex sample processing, our work provides a foundation for rapid, compact, and amplification-free molecular assays.

HIV-1 5'-Leader Mutations in Plasma Viruses Before and After the Development of Reverse Transcriptase Inhibitor-Resistance Mutations.

Background: HIV-1 RT initiation depends on interaction between viral 5'-leader RNA, RT, and host tRNA3Lys. We therefore sought to identify co-evolutionary changes between the 5'-leader and RT in viruses developing RT-inhibitor resistance mutations. Methods: We sequenced 5'-leader positions 37-356 of paired plasma virus samples from 29 individuals developing the NRTI-resistance mutation M184V, 19 developing an NNRTI-resistance mutation, and 32 untreated controls. 5'-leader variants were defined as positions where ≥20% of NGS reads differed from the HXB2 sequence. Emergent mutations were defined as nucleotides undergoing ≥4-fold change in proportion between baseline and follow-up. Mixtures were defined as positions containing ≥2 nucleotides each present in ≥20% of NGS reads. Results: Among 80 baseline sequences, 87 positions (27.2%) contained a variant; 52 contained a mixture. Position 201 was the only position more likely to develop a mutation in the M184V (9/29 vs. 0/32; p=0.0006) or NNRTI-resistance (4/19 vs. 0/32; p=0.02; Fisher's Exact Test) groups than the control group. Mixtures at positions 200 and 201 occurred in 45.0% and 28.8%, respectively, of baseline samples. Because of the high proportion of mixtures at these positions, we analyzed 5'-leader mixture frequencies in two additional datasets: five publications reporting 294 dideoxyterminator clonal GenBank sequences from 42 individuals and six NCBI BioProjects reporting NGS datasets from 295 individuals. These analyses demonstrated position 200 and 201 mixtures at proportions similar to those in our samples and at frequencies several times higher than at all other 5'-leader positions. Conclusions: Although we did not convincingly document co-evolutionary changes between RT and 5'-leader sequences, we identified a novel phenomenon, wherein positions 200 and 201, immediately downstream of the HIV-1 primer binding site exhibited an extraordinarily high likelihood of containing a nucleotide mixture. Possible explanations for the high mixture rates are that these positions are particularly error-prone or provide a viral fitness advantage.

Hepatitis E virus seropositivity in an ethnically diverse community blood donor population.

BACKGROUND AND OBJECTIVES: Hepatitis E virus (HEV) is an underrecognized and emerging infectious disease that may threaten the safety of donor blood supply in many parts of the world. We sought to elucidate whether our local community blood supply is at increased susceptibility for transmission of transfusion-associated HEV infections. MATERIALS AND METHODS: We screened 10,002 randomly selected donations over an 8-month period between 2017 and 2018 at the Stanford Blood Center for markers of HEV infection using commercial IgM/IgG serological tests and reverse transcriptase quantitative polymerase chain reaction assays (RT-qPCR). Donor demographic information, including gender, age, self-identified ethnicity, location of residence and recent travel, were obtained from the donor database and used to generate multivariate binary logistic regressions for risk factors of IgG seropositivity. RESULTS: A total of 10,002 blood donations from 7507 unique donors were screened, and there was no detectable HEV RNA by RT-qPCR. The overall seropositivity rate was 12.1% for IgG and 0.56% for IgM. Multivariate analysis of unique donors revealed a significantly higher risk of IgG seropositivity with increasing age, White/Asian ethnicities and residence in certain local counties. CONCLUSION: Although HEV IgG seroprevalence in the San Francisco Bay Area is consistent with ongoing infection, the screening of a large donor population did not identify any viraemic blood donors. While HEV is an underrecognized and emerging infection in other regions, there is no evidence to support routine blood screening for HEV in our local blood supply currently; however, periodic monitoring may still be required to assess the ongoing risk.