Rapid antigen testing for SARS-CoV-2 by lateral flow assay: A field evaluation of self- and professional testing at UK community testing sites.

BACKGROUND: The advent of lateral flow devices (LFDs) for SARS-CoV-2 detection enabled widespread use of rapid self-tests during the pandemic. While self-testing using LFDs is now common, whether self-testing provides comparable performance to professional testing was a key question that remained important for pandemic planning. METHODS: Three prospective multi-centre studies were conducted to compare the performance of self- and professional testing using LFDs. Participants tested themselves or were tested by trained (professional) testers at community testing sites in the UK. Corresponding qRT-PCR test results served as reference standard. The performance of Innova, Orient Gene and SureScreen LFDs by users (self) and professional testers was assessed in terms of sensitivity, specificity, and kit failure (void) rates. Impact of age, sex and symptom status was analysed using logistic regression modelling. RESULTS: 16,617 participants provided paired tests, of which 15,418 were included in the analysis. Self-testing with Innova, Orient Gene or SureScreen LFDs achieved sensitivities of 50 %, 53 % or 72 %, respectively, compared to qRT-PCR. Self and professional LFD testing showed no statistically different sensitivity with respect to corresponding qRT-PCR testing. Specificity was consistently equal to or higher than 99 %. Sex and age had no or only marginal impact on LFD performance while sensitivity was significantly higher for symptomatic individuals. Sensitivity of LFDs increased strongly to up to 90 % with higher levels of viral RNA measured by qRT-PCR. CONCLUSIONS: Our results support SARS-CoV-2 self-testing with LFDs, especially for the detection of individuals whose qRT-PCR tests showed high viral concentrations.

Swab pooling enables rapid expansion of high-throughput capacity for SARS-CoV-2 community testing.

BACKGROUND: The challenges of rapid upscaling of testing capacity were a major lesson from the COVID-19 pandemic response. The need for process adjustments in high-throughput testing laboratories made sample pooling a challenging option to implement. OBJECTIVE: This study aimed to evaluate whether pooling samples at source (swab pooling) was as effective as qRT-PCR testing of individuals in identifying cases of SARS-CoV-2 in real-world community testing conditions using the same high-throughput pipeline. METHODS: Two cohorts of 10 (Pool10: 1,030 participants and 103 pools) and 6 (Pool6: 1,284 participants and 214 pools) samples per pool were tested for concordance, sensitivity, specificity, and Ct value differences with individual testing as reference. RESULTS: Swab pooling allowed unmodified application of an existing high-throughput SARS-Cov-2 testing pipeline with only marginal loss of accuracy. For Pool10, concordance was 98.1% (95% Confidence interval: 93.3-99.8%), sensitivity was 95.7% (85.5-99.5%), and specificity was 100.0% (93.6-100.0%). For Pool6, concordance was 97.2% (94.0-99.0%), sensitivity was 97.5% (93.7-99.3%), and specificity was 96.4% (87.7-99.6%). Differences of outcomes measure between pool size were not significant. Most positive individual samples, which were not detected in pools, had very low viral concentration. If only individual samples with a viral concentration > 400 copies/ml (i.e. Ct value < 30) were considered positive, the overall sensitivity of pooling increased to 99.5%. CONCLUSION: The study demonstrated high sensitivity and specificity by swab pooling and the immediate capability of high-throughput laboratories to implement this method making it an option in planning of rapid upscaling of laboratory capacity for future pandemics.

Performance of antigen lateral flow devices in the UK during the alpha, delta, and omicron waves of the SARS-CoV-2 pandemic: a diagnostic and observational study.

BACKGROUND: Antigen lateral flow devices (LFDs) have been widely used to control SARS-CoV-2. We aimed to improve understanding of LFD performance with changes in variant infections, vaccination, viral load, and LFD use, and in the detection of infectious individuals. METHODS: In this diagnostic study, paired LFD and RT-PCR test results were prospectively collected from asymptomatic and symptomatic participants in the UK between Nov 4, 2020, and March 21, 2022, to support the National Health Service (NHS) England's Test and Trace programme. The LFDs evaluated were the Innova SARS-CoV-2 Antigen Rapid Qualitative Test, the Orient Gene Rapid Covid-19 (Antigen) Self-Test, and the Acon Flowflex SARS-CoV-2 Antigen Rapid Test (Self-Testing). Test results were collected across various community testing settings, including predeployment testing sites, routine testing centres, homes, schools, universities, workplaces, targeted community testing, and from health-care workers. We used multivariable logistic regression to analyse LFD sensitivity and specificity using RT-PCR as a reference standard, adjusting for viral load, LFD manufacturer, test setting, age, sex, test assistance, symptom status, vaccination status, and SARS-CoV-2 variant. National contact tracing data from NHS Test and Trace (Jan 1, 2021, to Jan 11, 2022) were used to estimate the proportion of transmitting index patients (with ≥1 RT-PCR-positive or LFD-positive contact) potentially detectable by LFDs (specifically Innova, as the most widely used LFD) with time, accounting for index viral load, variant, and symptom status. FINDINGS: We assessed 75 382 pairs of LFD and RT-PCR tests. Of these, 4131 (5·5%) were RT-PCR-positive. LFD sensitivity versus RT-PCR was 63·2% (95% CI 61·7-64·6) and specificity was 99·71% (95% CI 99·66-99·74). Increased viral load was independently associated with being LFD positive (adjusted odds ratio [aOR] 2·85 [95% CI 2·66-3·06] per 1 log10 copies per mL increase; p<0·0001). There was no evidence that LFD sensitivity differed for delta (B.1.617.2) infections versus alpha (B.1.1.7) or pre-alpha (B.1.177) infections (aOR 1·00 [0·69-1·45]; p=0·99), whereas omicron (BA.1 or BA.2) infections appeared more likely to be LFD positive (aOR 1·63 [1·02-2·59]; p=0·042). Sensitivity was higher in symptomatic participants (68·7% [95% CI 66·9-70·4]) than in asymptomatic participants (52·8% [50·1-55·4]). Among 347 374 unique index patients with probable onward transmission, 78·3% (95% CI 75·3-81·2) were estimated to have been detectable with LFDs (Innova), and this proportion was mostly stable with time and for successive variants. Overall, the estimated proportion of infectious index patients detectable by the Innova LFD was lower in asymptomatic patients (57·6% [53·6-61·9]) versus symptomatic patients (79·7% [76·7-82·5]). INTERPRETATION: LFDs remained able to detect most SARS-CoV-2 infections throughout vaccine roll-out and across different viral variants. LFDs can potentially detect most infections that transmit to others and reduce the risk of transmission. However, performance is lower in asymptomatic individuals than in symptomatic individuals. FUNDING: UK Health Security Agency, the UK Government Department of Health and Social Care, National Institute for Health Research (NIHR) Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, and the University of Oxford NIHR Biomedical Research Centre.

Recommendations for the introduction of metagenomic high-throughput sequencing in clinical virology, part I: Wet lab procedure.

Metagenomic high-throughput sequencing (mHTS) is a hypothesis-free, universal pathogen detection technique for determination of the DNA/RNA sequences in a variety of sample types and infectious syndromes. mHTS is still in its early stages of translating into clinical application. To support the development, implementation and standardization of mHTS procedures for virus diagnostics, the European Society for Clinical Virology (ESCV) Network on Next-Generation Sequencing (ENNGS) has been established. The aim of ENNGS is to bring together professionals involved in mHTS for viral diagnostics to share methodologies and experiences, and to develop application recommendations. This manuscript aims to provide practical recommendations for the wet lab procedures necessary for implementation of mHTS for virus diagnostics and to give recommendations for development and validation of laboratory methods, including mHTS quality assurance, control and quality assessment protocols.

Post-transplant lymphoproliferative disorder in adult renal transplant recipients: survival and prognosis.

Post-transplant lymphoproliferative disorder (PTLD) is a rare, serious complication following solid organ transplantation, with an incidence of 2.6 cases per 1000 patient years. Optimal treatment strategies and risk stratifications specific to kidney transplantation are lacking and PTLD mortality remains high. This study investigated survival and prognosis in 89 cases of PTLD presenting over 44 years at Manchester Royal Infirmary. Patient survival following diagnosis was 72% at 6 months, 67% at 1 year and 54% at 3 years. In multivariate analysis, a poorer 3 year survival was associated with acute kidney injury at diagnosis (p = 0.0001), impaired renal function (p = 0.04), early onset (p = 0.02), T cell disease (p = 0.02) and previous treatment with anti-thymocyte globulin (p = 0.04). The inclusion of graft function adds prognostic value to risk stratification and should be explored further. Strategies to improve survival should include timing and choice of immuno-chemotherapy, preparation for dialysis and aggressive surveillance for sepsis and treatment toxicity.

Single and multiple respiratory virus infections and severity of respiratory disease: a systematic review.

INTRODUCTION: There are suggestions that virus co-infections may influence the clinical outcome of respiratory virus illness. We performed a systematic review of the literature to summarise the evidence. METHODS: MEDLINE, EMBASE, Ovid and WEB of Science databases, major organisation websites and reference lists of published studies were searched. The quality of studies was assessed using the STROBE tool (von Elm et al., 1) Individual study data was analyzed using odds ratios and 95% confidence intervals as a measure of association between exposure (co-infection), patient outcome and results summarised using forest plots and tables RESULTS: Nineteen (19) studies from all over the world were identified and included in the review. Most of the studies 73.7% (14/19) recruited children ≤ 6 years old. Evidence on the role of co-infection in increasing disease severity was inconclusive. In five out of eight studies, co-infection significantly increased risk of admission to general ward (OR: 2.4, 95% CI: 1.3 - 4.4, p = 0.005; OR: 2.4, 95% CI: 1.1 - 7.7, P = 0.04; OR: 3.1, 95% CI: 2.0 - 5.1, p = <0.001; OR: 2.4, 95% CI: 1.7-3.4, p = <0.0001 and OR: 2.3, 95% CI: 1.1 - 5.1, p = 0.34), one found it did not (OR: 0.59, 95% CI: 0.4 - 0.9, p = 0.02) and the other 2 had insignificant results. Similarly on risk of admission to ICU, some studies found that co-infection significantly increased risk of admission to ICU (OR: 2.9, 95% CI: 1.4 - 5.9, p = 0.004 and OR: 3.0, 95% CI: 1.7 - 5.6, p = <0.0001), whereas others did not (OR: 0.18, 95% CI: 0.05 - 0.75, p = 0.02 and OR: 0.3, 95% CI: 0.2 - 0.6, p = <0.0001). There was no evidence for or against respiratory virus co-infections and risk of bronchiolitis or pneumonia. CONCLUSION: The influence of co-infections on severe viral respiratory disease is still unclear. The observed conflict in outcomes could be because they were conducted in different seasons and covered different years and periods. It could also be due to bias towards the null, especially in studies where only crude analysis was conducted. Future studies should employ stratified analysis.

Epidemiology of posttransplantation lymphoproliferative disorder in adult renal transplant recipients.

BACKGROUND: There is little information in the literature describing the relationship between posttransplantation lymphoproliferative disorder (PTLD) incidence and presentation with both recipient Epstein-Barr virus (EBV) serostatus and EBV status of PTLD histology, particularly in the late posttransplantation period. METHODS: This study reports the largest UK single-center, single-organ analysis of PTLD to date in a retrospective cohort study of 80 cases occurring in 4189 adult renal transplant recipients. RESULTS: The incidence rate was 2.6 cases per 1000 patient-years (95% confidence interval [95% CI], 2.1-3.2) for PTLD, 1.8 (95% CI, 1.4-2.4) for non-Hodgkin's lymphoma, and 0.2 (95% CI, 0.07-4.2) for Hodgkin's lymphoma. Non-Hodgkin's lymphoma occurred at a rate 7.6 times that of the adult general population in England, whereas the rate for Hodgkin's lymphoma was 5.9 times. The incidence of PTLD was highest during the 10th to 14th posttransplantation years. Early-onset disease was associated with EBV-seronegative recipient status, EBV-positive histology, and the involvement of extranodal sites. PTLD occurring in EBV-seronegative recipients was associated with EBV nuclear antigen antibody deficiency, polymorphic disease, and the involvement of extranodal sites. EBV-negative histology occurred in 32% of cases at a median time to presentation of 109 months. PTLD involving the allograft, central nervous system, and skin was uncommon and occurred late. CONCLUSION: The incidence of PTLD is highest in the late posttransplantation period. Close clinical surveillance and education for transplant recipients is required for the duration of time while immunosuppressed. Failure to detect EBV DNA in blood should not reassure, particularly in patients with symptoms such as abdominal pain, oropharyngeal complaints, neck lumps, and B-symptoms.

Merkel cell polyomavirus DNA in immunocompetent and immunocompromised patients with respiratory disease.

Merkel cell polyomavirus (MCPyV) was identified originally in association with a rare but aggressive skin cancer, Merkel cell carcinoma. The virus has since been found in the respiratory tract of some patients with respiratory disease. However, the role of MCPyV in the causation of respiratory disease has not been established. To determine the prevalence of MCPyV in 305 respiratory samples from immunocompetent and immunocompromised patients and evaluate their contribution to respiratory diseases, specimens were screened for MCPyV using single, multiplex, or real-time PCR; co-infection with other viruses was examined. Of the 305 samples tested, 10 (3.27%) were positive for MCPyV. The virus was found in two groups of patients: in 6 (2%) nasopharyngeal aspirate samples from children aged 26 days to 7 months who were immunocompetent; and in 4 (1.3%) of nasopharyngeal aspirate samples taken from patients aged 41 to 69 years who were severely immunosuppressed from leukemia or transplant therapy. Both groups had upper or lower respiratory tract infection. Co-infections with other viruses were found in 30% of the MCPyV positive samples. The data present a pattern of infection similar to that seen with the polyomaviruses JC and BK in which the virus is acquired during childhood, probably by the respiratory route. The viruses then establish latency and become reactivated in the event of immunosuppression.

Evidence of simian virus 40 infection in multiple organ transplant recipients with renal dysfunction.

Electron microscopy (EM), real-time polymerase chain reaction (PCR) and conventional PCR were used to identify viruses associated with infection in 2 transplantation patients. An autologous haematopoietic stem cell, liver and renal transplant recipient was found to be positive for simian virus 40 (SV40). Dual BK virus and SV40 infection was found in a heart and renal transplantation patient. SV40 infection can occur in immunocompromised patients.

Multitypic hepatitis C virus infection identified by real-time nucleotide sequencing of minority genotypes.

The prevalence of concurrent multitypic hepatitis C virus (HCV) infection is uncertain. A sensitive and specific approach to identifying minority HCV genotypes in blood is presented. Following serum extraction and reverse transcription PCR to amplify cDNA originating from the viral 5' noncoding region, the amplified product mixture was treated with genotype-specific restriction endonuclease to digest the dominant genotype. Residual amplicons were subjected to PCR cloning and then to real-time DNA sequencing using a Pyrosequencer to identify the remaining genotypes. Dilution experiments showed that minority genotypes may be detected when they represent 1:10,000 of the total population and in serum specimens with viral loads as low as 1,000 IU/ml. Of 37 patients with bleeding disorders and 44 injecting drug users, infection by more than one HCV genotype was found in 7 (19%) and 4 (9%) patients, respectively. The low rate of detection in people at high risk of repeated HCV infection suggests that multitypic HCV carriage is uncommon.

Comparison of immunoassays for differentiation of herpes simplex virus type 1 and 2 antibodies.

OBJECTIVE: To asses the commercial available enzyme-linked immunosorbent assays (ELISA) for differentiation of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) antibodies. METHODS: The study was performed between January 1997 to November 2002 in the Division of Virology, Department of Pathological Sciences, Central Manchester Healthcare Trust and University of Manchester, Manchester, United Kingdom. Assays based upon type-specific glycoprotein G-1 (gG-1) for HSV-1, and glycoprotein G-2 (gG-2) from HSV-2 were evaluated to differentiate between HSV-1 and HSV-2 antibodies. Using 5 different ELISA tests, 2 panels of serum samples were tested. Panel one consisted of 88 sera, selected from the serum bank of the Clinical Virology Laboratory, Manchester Royal Infirmary; panel 2 comprised of 90 sera selected from samples collected from Bangladeshi female commercial workers. RESULTS: The data of this study showed that a high rate of gG-1 based immunoassays ranged from 87.9-100% for sensitivity and 51.5-100% specificity. CONCLUSION: Although there are several immunoassays were claimed to differentiate between HSV-1 and HSV-2 antibodies, selection of these assays should be carefully interpreted with the overall clinical framework provided by detailed sexual history and genital examination.

Childhood encephalopathy: viruses, immune response, and outcome.

This study examined children with an acute encephalopathy illness for evidence of viral infection, disordered blood-brain barrier function, intrathecal immunoglobulin synthesis, and interferon (IFN) production, and related their temporal occurrence to outcome. A prospective study of 22 children (13 males, 9 females; age range 1mo to 13y, median 2y 4mo), recorded clinical details, with serum and cerebrospinal fluid (CSF) analysis near presentation and then on convalescent specimens taken up to day 39 of the neurological illness. Outcome was assessed with standard scales between 18 months and 3 years after presentation. A history consistent with viral infection was given in 17 children but laboratory evidence of viral infection was found in only 7 (7/17). In 18 out of 21 children, an elevated CSF:serum albumin ratio indicative of impairment of the blood-CSF and blood-brain barriers was detected at some stage of the illness. In 14 of the 15 children with a raised immunoglobulin G index, and in 12 of the 14 children where the CSF was positive for oligoclonal bands, this was preceded by, or was observed at the same time as, an abnormal albumin ratio. Sixteen children (16/18) had elevated IFN-alpha levels in serum, or CSF, or in both. We conclude that these findings indicate an initial disruption of the blood-brain barrier followed by intrathecal antibody production by activated lymphocytes, clonally restricted to a few antigens. This is the first in vivo study to show this as an important pathogenetic mechanism of encephalitis in children. Poor outcome was associated with young age, a deteriorating electroencephalogram pattern from grade 1 to grade 2, and the degree of blood-brain barrier impairment, particularly when prolonged, but not with Glasgow Coma Scale score. The persistence of IFN-alpha was associated with a good prognosis.

Three nonfatal cases of neonatal adenovirus infection.

Neonatal adenovirus infection is considered a rare and fatal disease. Three nonfatal neonatal adenovirus infections manifesting as conjunctivitis or conjunctivitis with other nonspecific symptoms are described. Adenovirus DNA was detected by PCR in eye swabs from two patients and in both cerebrospinal fluid and eye swabs in the third patient.

Detection of human cytomegalovirus, human herpesvirus type 6 and human herpesvirus type 7 in urine specimens by multiplex PCR.

OBJECTIVES: To develop a sensitive multiplex PCR to detect HCMV, HHV6 and HHV7, to test this PCR on urine specimens sent to the virus diagnostic laboratory and on stored urine samples from HIV-positive patients and their HIV-negative partners and to compare the sensitivity of the multiplex PCR with the diagnostic laboratory's routine service for the detection of HCMV. STUDY DESIGN: Primers specific for each of the three viruses were combined in a multiplex PCR that was then optimised for sensitivity. This PCR was applied prospectively to 413 unselected routine urine specimens over a 1 year period and retrospectively to 258 urine specimens from 63 HIV-positive patients and 10 HIV-negative partners. METHODS: In the prospective study, the multiplex PCR detected 40 specimens positive for HCMV alone, 10 for HHV6, 3 for HHV7 and 3 with a dual infection of HCMV and HHV6. The sensitivity for HCMV was 93.5% by multiplex PCR compared to 28.3% by culture. HHV6 DNA was detected in 6 neonates (2-21 days) and HHV7 DNA in 2 neonates (4 and 20 days). In the retrospective study of HIV patients, HCMV was the most commonly detected virus (55.6%) compared to HHV6 (7.9%) and HHV7 (4.8%). CONCLUSIONS: . The multiplex PCR was significantly more sensitive than non-DNA based procedures for the detection of HCMV. Urine may be a useful non-invasive specimen for the detection of HHV6 and HHV7 and their presence in neonates suggest perinatal transmission or the possibility of in utero infection.

Reliability of nucleic acid amplification methods for detection of Chlamydia trachomatis in urine: results of the first international collaborative quality control study among 96 laboratories.

The first European Quality Control Concerted Action study was organized to assess the ability of laboratories to detect Chlamydia trachomatis in a panel of urine samples by nucleic acid amplification tests (NATs). The panel consisted of lyophilized urine samples, including three negative, two strongly positive, and five weakly positive samples. Ninety-six laboratories in 22 countries participated with a total of 102 data sets. Of 204 strongly positive samples 199 (97.5%) were correctly reported, and of 506 weakly positive samples 466 (92.1%) were correctly reported. In 74 (72.5%) data sets correct results were reported on all samples, and 17 data sets (16.7%) showed either one false-negative or one false-positive result. In another 11 data sets, two or more incorrect results were reported, and two data sets reported a false-positive result on one negative sample. The Roche COBAS Amplicor test was performed in 44 (43%) data sets, the Abbott LCx assay was performed in 31 (30%) data sets, the Roche Amplicor manual assay was performed in 9 (9%) data sets, an in-house PCR was performed in 9 (9%) data sets, the Becton Dickinson ProbeTec ET assay was performed in 5 (4.9%) data sets, and the GenProbe TMA assay was performed in 4 (3.9%) data sets. The results of the Roche Amplicor manual (95.6% correct), COBAS Amplicor (97.0%), and Abbott LCx (94.8%) tests were comparable (P = 0.48). The results with the in-house PCR, BD ProbeTec ET, and GenProbe TMA tests were reported correctly in 88.6, 98, and 92.5% of the tests, respectively. Freeze-drying of clinical urine specimens proved to be a successful method for generating standardized, stable, and easy-to-transport samples for the detection of C. trachomatis by using NATs. Although the results, especially the specificity, for this proficiency panel were better than most quality control studies, sensitivity problems occurred frequently, underlining the need for good laboratory practice and reference reagents to monitor the performance of these assays.

External quality assessment program for qualitative and quantitative detection of hepatitis C virus RNA in diagnostic virology.

To assess the performance of laboratories in detecting and quantifying hepatitis C virus (HCV) RNA levels in HCV-infected patients, we distributed two proficiency panels for qualitative and quantitative HCV RNA testing. The panels were designed by the European Union Quality Control Concerted Action, prepared by Boston Biomedica Inc., and distributed in May 1999 (panel 1) and February 2000 (panel 2). Each panel consisted of two negative samples and six positive samples, with HCV RNA target levels from 200 to 500,000 copies/ml. Panel 1 had four samples with at least 50,000 copies/ml, and panel 2 had two samples with at least 50,000 copies/ml. Fifty-seven laboratories submitted 45 qualitative and 35 quantitative data sets on panel 1, and 81 laboratories submitted 75 qualitative and 48 quantitative data sets on panel 2. In both panels, about two-thirds of the qualitative data sets and >90% of the quantitative data sets were obtained with commercial assays. With each panel, two data sets gave one false-positive result, corresponding to false-positivity rates of 1.3% and 0.8% for panel 1 and panel 2, respectively. Samples containing at least 50,000 copies/ml were found positive in 97% and 99% of the cases with panel 1 and panel 2, respectively. In contrast, the positive samples containing < or =5,000 copies/ml were reported positive in only 71% and 77% of the cases with panel 1 and panel 2, respectively. Adequate or better scores on qualitative results (all results correct or only the low-positive samples missed) were obtained in 84% (panel 1) and 80% (panel 2) of the data sets. In the analysis of quantitative results, 60% (panel 1) and 73% (panel 2) of the data sets obtained an adequate or better score (> or =80% of the positive results within the range of the geometric mean +/- 0.5 log(10)). Our results indicate that considerable improvements in molecular detection and quantitation of HCV have been achieved, particularly through the use of commercial assays. However, the lowest detection levels of many assays are still too high, and further standardization is still needed. Finally, this study underlines the importance of proficiency panels for monitoring the quality of diagnostic laboratories.

Adenovirus infections following allogeneic stem cell transplantation: incidence and outcome in relation to graft manipulation, immunosuppression, and immune recovery.

Adenovirus infections occur in 5% to 21% of patients following stem cell transplantation (SCT), with an associated mortality of up to 50%. However, a lack of prospective studies has hampered further developments in the understanding and management of this infection in the posttransplantation setting. We prospectively studied the incidence and outcome of adenovirus infections after SCT using preemptive screening and a policy of reduction or withdrawal of immunosuppressive therapy if the virus was isolated. The incidence of adenovirus infection was 19.7% (15 of 76), and the virus was isolated exclusively in recipients of T-cell-depleted grafts. Patients receiving 50 or 100 mg alemtuzumab in vivo were at the greatest risk of adenovirus infection (45% probability) regardless of donor type, and this was related to the slower lymphocyte recovery. Six (40%) of the 15 adenovirus-infected patients developed adenovirus disease. Severe lymphocytopenia (less than 300/microL) at the time of first detection of adenovirus was a major risk factor for development of adenovirus disease (P =.001). In addition, failure to reduce immunosuppression (P =.04) and a positive result of adenovirus polymerase chain reaction (PCR) in blood at diagnosis (P =.01) were both associated with fatal adenovirus disease. On the basis of this study, we recommend active surveillance for adenovirus infection in T-cell-depleted SCT and withdrawal or reduction of immunosuppressive treatment, if possible, in patients with adenovirus infection. Preemptive antiviral therapy is warranted for patients with severe lymphocytopenia or positive blood PCR, and in those in whom immunosuppressive therapy cannot be reduced.