Omicron breakthrough infections after triple-dose inactivated COVID-19 vaccination: A comprehensive analysis of antibody and T-cell responses.

This study longitudinally evaluated the immune response in individuals over a year after receiving three doses of an inactivated SARS-CoV-2 vaccine, focusing on reactions to Omicron breakthrough infections. From 63 blood samples of 37 subjects, results showed that the third booster enhanced the antibody response against Alpha, Beta, and Delta VOCs but was less effective against Omicron. Although antibody titres decreased post-vaccination, SARS-CoV-2-specific T-cell responses, both CD4+ and CD8+, remained stable. Omicron breakthrough infections significantly improved neutralization against various VOCs, including Omicron. However, the boost in antibodies against WT, Alpha, Beta, and Delta variants was more pronounced. Regarding T cells, breakthrough infection predominantly boosted the CD8+ T-cell response, and the intensity of the spike protein-specific T-cell response was roughly comparable between WT and Omicron BA.5.

Metabolic biomarkers significantly enhance the prediction of HBV-related ACLF occurrence and outcomes.

BACKGROUND & AIMS: Acute-on-chronic liver failure (ACLF) is a clinical syndrome associated with high short-term mortality in patients with chronic liver disease. Chronic hepatitis B is the main cause of ACLF (HBV-ACLF) in China and other Asian countries. To improve disease management and survival for patients with ACLF, we aimed to discover novel biomarkers to enhance HBV-ACLF diagnosis and prognostication. METHODS: We performed a metabolomics profiling of 1,024 plasma samples collected from patients with HBV-related chronic liver disease with acute exacerbation at hospital admission in a multi-year and multi-center prospective study (367 ACLF and 657 non-ACLF). The samples were randomly separated into equal halves as a discovery set and a validation set. We identified metabolites associated with 90-day mortality in the ACLF group and the progression to ACLF within 28 days in the non-ACLF group (pre-ACLF) using statistical analysis and machine learning. We developed diagnostic algorithms in the discovery set and used these to assess the findings in the validation set. RESULTS: ACLF significantly altered the plasma metabolome, particularly in membrane lipid metabolism, steroid hormones, oxidative stress pathways, and energy metabolism. Numerous metabolites were significantly associated with 90-day mortality in the ACLF group and/or pre-ACLF in the non-ACLF group. We developed algorithms for the prediction of 90-day mortality in patients with ACLF (area under the curve 0.87 and 0.83 for the discovery set and validation set, respectively) and the diagnosis of pre-ACLF (area under the curve 0.94 and 0.88 for the discovery set and validation set, respectively). To translate our discoveries into practical clinical tests, we developed targeted assays using liquid chromatography-mass spectrometry. CONCLUSIONS: Based on novel metabolite biomarkers, we established tests for HBV-related ACLF with higher accuracy than existing methods. CLINICAL TRIAL NUMBER: NCT02457637 and NCT03641872. IMPACT AND IMPLICATIONS: Acute-on-chronic liver failure (ACLF) is a clinical syndrome associated with high short-term mortality affecting 25% of patients hospitalized with cirrhosis. Chronic hepatitis B is the main etiology of ACLF in China and other Asian counties. There is currently no effective therapy. Early diagnosis and accurate prognostication are critical for improving clinical outcomes in patients with ACLF. Based on novel metabolite biomarkers, we developed liquid chromatography-mass spectrometry tests with improved accuracy for the early diagnosis and prognostication of HBV-related ACLF. The liquid chromatography-mass spectrometry tests can be implemented in clinical labs and used by physicians to triage patients with HBV-related ACLF to ensure optimized clinical management.

Severe anemia is associated with increased short-term and long-term mortality in patients hospitalized with cirrhosis.

INTRODUCTION AND OBJECTIVES: The relationship between anemia and the outcome of patients with cirrhosis is not completely clear. Therefore, we performed this large-scale epidemiological study to investigate the prevalence and severity of anemia in patients with cirrhosis and acute decompensation or liver injury and how anemia impacts short-term and long-term outcomes. PATIENTS AND METHODS: Patients with cirrhosis and acute decompensation (AD) or acute liver injury (ALI) were enrolled in the Chinese AcuTe on CHronic LIver FailurE (CATCH-LIFE) studies, which consisted of two large, multicenter, prospective, observational cohorts between January 2015 and December 2016 and July 2018 and January 2019. We conducted data analysis on the prevalence of anemia and determined the relationship between anemia and prognosis. RESULTS: Among 1979 patients, 1389 (70.2%) had anemia, among whom 599 (41.3%) had mild anemia, 595 (15.8%) had moderate anemia and 195 (2.4%) had severe anemia. A linear association between hemoglobin level and 90-day or 1-year LT-free mortality was shown, and a 10 g/L decrease in hemoglobin level was associated with a 6.8% extra risk of 90-day death and a 5.7% extra risk of 1-year death. Severe anemia was an independent risk factor for 90-day [HR=1.649 (1.100, 2.473), p=0.016] and 1-year LT-free mortality [HR=1.610 (1.159, 2.238), p=0.005]. Multinomial logistic regression analysis further identified that severe anemia was significantly associated with post-28-day mortality but not within-28-day mortality. CONCLUSIONS: Anemia is common in patients with cirrhosis admitted for acute events. Severe anemia was associated with poor 90-day and 1-year prognoses in these patients.

Prevalence and Clinical Significance of Portal Vein Thrombosis in Patients With Cirrhosis and Acute Decompensation.

BACKGROUND & AIMS: Portal vein thrombosis (PVT) is a common and serious complication in patients with cirrhosis. However, little is known about PVT in patients with cirrhosis and acute decompensation (AD). We investigated the prevalence and clinical significance of PVT in nonmalignant patients with cirrhosis and AD. METHODS: We performed a retrospective study of 2 cohorts of patients with acute exacerbation of chronic liver disease who participated in the Chinese AcuTe on CHronic LIver FailurE study, established by the Chinese Chronic Liver Failure Consortium, from January 2015 through December 2016 (n = 2600 patients) and July 2018 through January 2019 (n = 1370 patients). We analyzed data on the prevalence, clinical manifestations, and risk factors of PVT from 2826 patients with cirrhosis, with and without AD. RESULTS: The prevalence of PVT in patients with cirrhosis and AD was 9.36%, which was significantly higher than in patients with cirrhosis without AD (5.24%) (P = .04). Among patients with cirrhosis and AD, 63.37% developed PVT recently (the first detected PVT with no indication of chronic PVT). Compared with patients without PVT, a significantly higher proportion of patients with PVT had variceal bleeding (47.33% vs 19.63%; P < .001) and patients with PVT had a significantly higher median serum level of D-dimer (2.07 vs 1.25; P < .001). Splenectomy and endoscopic sclerotherapy were independent risk factors for PVT in patients with cirrhosis and AD. The 1-year mortality rate did not differ significantly between patients with vs without PVT. CONCLUSIONS: In an analysis of data from 2826 patients with cirrhosis, a significantly higher proportion of those with AD had PVT than those without AD. PVT was associated with increased variceal bleeding, which would increase the risk for AD. Strategies are needed to prevent PVT in patients with cirrhosis, through regular screening, to reduce portal hypertension. ClinicalTrials.gov no: NCT02457637 and NCT03641872.

CD4 T cell loss and Th2 and Th17 bias are associated with the severity of severe fever with thrombocytopenia syndrome (SFTS).

Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease caused by a novel bunyavirus with high mortality. Immune suppression is thought to be crucial in disease progression. However, data on immune responses during SFTS are scarce. This study aimed to evaluate the changes in CD4 T-cell subsets throughout the entirety of infection and analyse their relationships with disease severity in SFTS patients. In parallel with CD4 T-cell depletion, decreased Th1, Th2 and Treg numbers, but comparable Th17-cell numbers, were observed in deceased patients compared with those in surviving patients. Additionally, increased Th2 and Th17-cell percentages in the residual CD4 T-cell population led to aberrant Th2/Th1 and Th17/Treg ratios, which were positively correlated with disease severity. Collectively, our data indicated that CD4 T-cell deficiency, Th2 and Th17 bias were closely correlated with the severity of SFTS, indicating therapeutic potential of early immune interventions to ameliorate disease severity.

The clinical courses of HBV-related acute-on-chronic liver failure and a multi-state model to predict disease evolution.

BACKGROUND AND AIMS: Acute-on-chronic liver failure (ACLF) is a highly dynamic syndrome. The objective of this study was to delineate the clinical course of patients with HBV-ACLF and to develop a model to estimate the temporal evolution of disease severity. METHODS: We enrolled eligible patients from 2 large, multicenter prospective cohorts. The ACLF grade, organ failures, and outcomes were assessed at multiple time points (days 1/4/7/14/21/28). Probabilities for ACLF transitions between these disease states and to death within 28 days were calculated using a multi-state model that used baseline information and updated ACLF status. The model was validated in independent patients. RESULTS: Among all the 445 patients with HBV-ACLF, 76 represented disease progression, 195 had a stable or fluctuating course, 8 with improvement, and the remaining 166 with resolution within 28-day follow-up. New coagulation (63.64%) or renal failure (45.45%) was frequently observed during early progression. Patients with disease progression had a higher incidence of new episodes of ascites [10 (13.16%) vs. 22 (5.96%), p = 0.027] and HE [13(17.11%) vs. 21 (5.69%), p = 0.001], and a significant increase in white blood cell count. The multi-state model represented dynamic areas under the receiver operating characteristic curves ranging from 0.71 to 0.84 for predicting all ACLF states and death at 4, 7, 14, 21, and 28 days post-enrollment and from 0.73 to 0.94 for predicting death alone, performing better than traditional prognostic scores. CONCLUSIONS: HBV-ACLF is a highly dynamic syndrome with reversibility. The multi-state model is a tool to estimate the temporal evolution of disease severity, which may inform clinical decisions on treatment.

Role of precipitants in transition of acute decompensation to acute-on-chronic liver failure in patients with HBV-related cirrhosis.

Background & Aims: Pre-acute-on-chronic liver failure (ACLF) is a distinct intermediate stage between acute decompensation (AD) and ACLF. However, identifying patients with pre-ACLF and predicting progression from AD to ACLF is difficult. This study aimed to identify pre-ACLF within 28 days, and to develop and validate a prediction model for ACLF in patients with HBV-related decompensated cirrhosis. Methods: In total, 1,736 patients with HBV-related cirrhosis and AD were enrolled from 2 large-scale, multicenter, prospective cohorts. ACLF occurrence within 28 days, readmission, and 3-month and 1-year outcomes were collected. Results: Among 970 patients with AD without ACLF in the derivation cohort, the 94 (9.6%) patients with pre-ACLF had the highest 3-month and 1-year LT-free mortality (61.6% and 70.9%, respectively), which was comparable to those with ACLF at enrollment (57.1% and 67.1%); the 251 (25.9%) patients with unstable decompensated cirrhosis had mortality rates of 22.4% and 32.1%, respectively; while the 507 (57.9%) patients with stable decompensated cirrhosis had the best outcomes (1-year mortality rate of 2.6%). Through Cox proportional hazard regression, specific precipitants, including hepatitis B flare with HBV reactivation, spontaneous hepatitis B flare with high viral load, superimposed infection on HBV, and bacterial infection, were identified to be significantly associated with ACLF occurrence in the derivation cohort. A model that incorporated precipitants, indicators of systemic inflammation and organ injuries reached a high C-index of 0.90 and 0.86 in derivation and validation cohorts, respectively. The optimal cut-off value (0.22) differentiated high-risk and low-risk patients, with a negative predictive value of 0.95. Conclusions: Three distinct clinical courses of patients with AD are validated in the HBV-etiology population. The precipitants significantly impact on AD-ACLF transition. A model developed by the precipitant-systemic inflammation-organ injury framework could be a useful tool for predicting ACLF occurrence. Clinical trial number: NCT02457637 and NCT03641872. Lay summary: It was previously shown that patients with decompensated cirrhosis could be stratified into 3 groups based on their short-term clinical prognoses. Herein, we showed that this stratification applies to patients who develop cirrhosis as a result of hepatitis B virus infection. We also developed a precipitant-based model (i.e. a model that incorporated information about the exact cause of decompensation) that could predict the likelihood of these patients developing a very severe liver disease called acute-on-chronic liver failure (or ACLF).

Prognosis prediction performs better in patients with non-cirrhosis hepatitis B virus-related acute-on-chronic liver failure than those with cirrhosis.

Background: The accurate prediction of the outcome of hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is impeded by population heterogeneity. The study aimed to assess the impact of underlying cirrhosis on the performance of clinical prediction models (CPMs). Methods: Using data from two multicenter, prospective cohorts of patients with HBV-ACLF, the discrimination, calibration, and clinical benefit were assessed for CPMs predicting 28-day and 90-day outcomes in patients with cirrhosis and those without, respectively. Results: A total of 919 patients with HBV-ACLF were identified by Chinese Group on the Study of Severe Hepatitis B (COSSH) criteria, including 675 with cirrhosis and 244 without. COSSH-ACLF IIs, COSSH-ACLFs, Chronic Liver Failure-Consortium Acute-on-Chronic Liver Failure score (CLIF-C ACLFs), Tongji Prognostic Predictor Model score (TPPMs), Model for End-Stage Liver Disease score (MELDs), and MELD-Sodium score (MELD-Nas) were all strong predictors of short-term mortality in patients with HBV-ACLF. In contrast to a high model discriminative capacity in ACLF without cirrhosis, each prognostic model represents a marked decline of C-index, net reclassification index (NRI), and integrated discrimination improvement (IDI) in predicting either 28-day or 90-day prognosis of patients with cirrhosis. The hazard analysis identified largely overlapping risk factors of poor outcomes in both subgroups, while serum bilirubin was specifically associated with short-term mortality in patients with cirrhosis and blood urea nitrogen in patients without cirrhosis. A subgroup analysis in patients with cirrhosis showed a decline of discrimination of CPMS in those with ascites or infections compared to that in those without. Conclusion: Predicting the short-term outcome of HBV-ACLF by CPMs is optimal in patients without cirrhosis but limited in those with cirrhosis, at least partially due to the complicated ascites or infections.

Longitudinal characterization of phenotypic profile of T cells in chronic hepatitis B identifies immune markers associated with HBsAg loss.

BACKGROUND: The current desirable endpoint of treatment against chronic hepatitis B virus infection (cHBV) is to achieve a functional cure, which is defined as HBsAg loss (sAg-L) with or without anti-HBs seroconversion. However, the immunological features that are associated with functional cure have not been studied in detail. METHODS: 172 cHBV patients (67 HBeAg+ and 105 HBeAg-), including 141 HBsAg retained (sAg-R) patients (115 chronic hepatitis and 26 asymptomatic carriers), 31 sAg-L patients, and 24 healthy individuals (vaccinated but not infected with HBV) were examined for their T cell phenotypic profile and HBV-specific T cell responses by flow cytometry. 18 cHBV patients with low serum HBsAg levels were also longitudinally followed for their T cell phenotypic profile and HBV-specific T cell responses up to 60 weeks. FINDINGS: sAg-L patients showed distinct CD4+ and CD8+ T cell phenotype fingerprints compared to those of sAg-R patients, as mainly indicated by the upregulation of HLA-DR on both CD4+ and CD8+ T cells, and a potent HBcAg-specific CD8+ T cell response. The changes in the T cell phenotype in cHBV patients were even more profound during rapid HBsAg decrease and was associated with interferon α treatment. The expression of HLA-DR (r = 0·3269, p = 0·0037), CD95 (r = 0·2796, p = 0·0151), CD40L (r = 0·2747, p = 0·0156), CTLA-4 (r = 0·2786, p = 0·0148), TIM-3 (r = 0·3082, p = 0·0068), CD107a (r = 0·3597, p = 0·0013) on CD4+ T cells, and HLA-DR (r = 0·3542, p = 0·0016), CD69 (r = 0·2507, p = 0·0279), CD107a (r = 0·2875, p = 0·0112) on CD8+ T cells were positively correlated with the rate of HBsAg decrease. The expression of HLA-DR (r = 0·2846, p = 0·0009) and CD95 (r = 0·2442, p = 0·0049) on CD8+ T cells were positively correlated with the magnitude of the HBcAg-specific T cell responses in cHBV patients. Importantly, CTLA-4, CD95 and CD107a expression on CD4+ T cells, as well as HLA-DR and TIM-3 expression on CD8+ T cells in combination with HBsAg quantification were identified as potential predictive factors for sAg-L within 48 weeks in cHBV patients. INTERPRETATION: The onset of HBsAg decrease and subsequent loss in cHBV patients on treatment is associated with significant alterations of both CD4+ and CD8+ T cell phenotypes. Characterization of the T cell phenotype in cHBV patients may present predicative value for sAg-L. FUNDING: National Natural Science Foundation of China, National Scientific and Technological Major Project of China, Integrated Innovative Team for Major Human Diseases Program of Tongji Medical College, "Double-First Class" Project for the International Cooperation Center on Infection and Immunity, HUST.

Analysis of the Long-Term Impact on Cellular Immunity in COVID-19-Recovered Individuals Reveals a Profound NKT Cell Impairment.

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affected over 120 million people and killed over 2.7 million individuals by March 2021. While acute and intermediate interactions between SARS-CoV-2 and the immune system have been studied extensively, long-term impacts on the cellular immune system remain to be analyzed. Here, we comprehensively characterized immunological changes in peripheral blood mononuclear cells in 49 COVID-19-convalescent individuals (CI) in comparison to 27 matched SARS-CoV-2-unexposed individuals (UI). Despite recovery from the disease for more than 2 months, CI showed significant decreases in frequencies of invariant NKT and NKT-like cells compared to UI. Concomitant with the decrease in NKT-like cells, an increase in the percentage of annexin V and 7-aminoactinomycin D (7-AAD) double-positive NKT-like cells was detected, suggesting that the reduction in NKT-like cells results from cell death months after recovery. Significant increases in regulatory T cell frequencies and TIM-3 expression on CD4 and CD8 T cells were also observed in CI, while the cytotoxic potential of T cells and NKT-like cells, defined by granzyme B (GzmB) expression, was significantly diminished. However, both CD4 and CD8 T cells of CI showed increased Ki67 expression and were fully able to proliferate and produce effector cytokines upon T cell receptor (TCR) stimulation. Collectively, we provide a comprehensive characterization of immune signatures in patients recovering from SARS-CoV-2 infection, suggesting that the cellular immune system of COVID-19 patients is still under a sustained influence even months after the recovery from disease.IMPORTANCE Wuhan was the very first city hit by SARS-CoV-2. Accordingly, the patients who experienced the longest phase of convalescence following COVID-19 reside here. This enabled us to investigate the "immunological scar" left by SARS-CoV-2 on cellular immunity after recovery from the disease. In this study, we characterized the long-term impact of SARS-CoV-2 infection on the immune system and provide a comprehensive picture of cellular immunity of a convalescent COVID-19 patient cohort with the longest recovery time. We revealed that the cellular immune system of COVID-19 patients is still under a sustained influence even months after the recovery from disease; in particular, a profound NKT cell impairment was found in the convalescent phase of COVID-19.

Depletion but Activation of CD56dimCD16+ NK Cells in Acute Infection with Severe Fever with Thrombocytopenia Syndrome Virus.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high mortality (12%-30%). The mechanism by which the SFTS bunyavirus (SFTSV) causes severe illness remains unclear. To evaluate the phenotypic and functional characteristics of the NK cell subsets in SFTS patients, twenty-nine SFTS patients were sequentially sampled from admission until recovery. Phenotypic and functional characteristics of NK cell subsets in circulating blood were analysed via flow cytometry. Then, correlations between NK cell subset frequencies and the SFTS index (SFTSI) were evaluated in all SFTS patients (15 mild, 14 severe) upon admission. The frequencies of CD56dimCD16+ NK cells were greatly decreased in early SFTSV infection and were negatively correlated with disease severity. Additionally, higher Ki-67 and granzyme B expression and relatively lower NKG2A expression in CD56dimCD16+ NK cells were observed in acute infection. Moreover, the effector function of CD56dim NK cells was increased in the acute phase compared with the recovery phase in nine severe SFTS patients. Additionally, interleukin (IL)-15, interferon (IFN)-α, IL-18 and IFN-γ secretion was markedly increased during early infection. Collectively, despite depletion of CD56dimCD16+ NK cells, activation and functional enhancement of CD56dimCD16+ NK cells were still observed, suggesting their involvement in defence against early SFTSV infection.

Dynamic changes in the immunological characteristics of T lymphocytes in surviving patients with severe fever with thrombocytopenia syndrome (SFTS).

OBJECTIVE: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high mortality. T cell deficiency has recently been described, but the changes in T cell functionality during acute SFTS virus (SFTSV) infection and the mechanisms leading to T lymphocyte death remain largely unknown. This study was conducted to evaluate T cell functionality and the expression of apoptotic/proliferation and activation/inhibition markers during acute SFTSV infection. METHODS: Twenty-eight surviving SFTS patients were sequentially sampled during their entire hospital stay. SFTSV RNA copies were investigated using real-time RT-PCR. The expression levels of apoptotic markers (annexin V and CD95) and proliferation and activation markers (Ki-67, HLA-DR, and CD25) and the expression levels of programmed cell death-1 (PD-1), interferon gamma (IFN-γ), and granzyme B in T cells were evaluated by flow cytometry for the SFTS patients. RESULTS: In parallel with T cell depletion, higher annexin V and CD95 expression was observed in SFTS patients. Additionally, the expression levels of Ki-67, HLA-DR, CD25, and PD-1 and the levels of IFN-γ and granzyme B in T lymphocytes were markedly increased in the SFTS patients. CONCLUSIONS: T cell proliferation, activation, and functional enhancement were apparent despite the observation of T cell apoptosis, suggesting that these processes are involved in the complex protective response to SFTSV infection.

Decreased myeloid dendritic cells indicate a poor prognosis in patients with severe fever with thrombocytopenia syndrome.

OBJECTIVES: Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease caused by a novel bunyavirus in which host immune system suppression is thought to be crucial in the development of disease. This study was designed to study the frequencies and activation status of dendritic cells (DCs) at different stages of SFTS and their association with disease severity. METHODS: All confirmed SFTS patients (N=115) were recruited from the Wuhan Union Hospital in 2015; routine laboratory parameters were collected. The frequencies, phenotypes, and subsets of circulating DCs, including myeloid and plasmacytoid dendritic cells (mDCs and pDCs), were analyzed by flow cytometry. Serum levels of interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNF-α) were detected by ELISA. The laboratory parameters and other clinical events related to mortality were assessed by multivariate logistic regression analysis and receiver operating characteristic (ROC) curves. RESULTS: The frequency of circulating mDCs, especially from day 9 after disease onset, could serve as a valuable prognostic biomarker for the outcome in SFTS patients (area under the curve=0.929, p<0.0001). In addition, persistent down-regulation of the co-stimulatory molecules CD80/CD86 on the mDCs was observed during the disease process. Moreover, levels of mDCs were inversely correlated with the production of IL-6, IL-10, and TNF-α and with viral load at admission. CONCLUSIONS: The present results indicate that DCs might be functionally impaired in SFTS. A decreased level of circulating mDCs was closely correlated with the severity of SFTS.

A simple and practical score model for predicting the mortality of severe fever with thrombocytopenia syndrome patients.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging disease with a high fatality rate. The risk factors for death are not clearly identified, and there is no clinical score model to predict the prognosis. We retrospectively collected the clinical information of clinical symptoms and laboratory parameters of SFTS patients on admission. After analyzing the clinical characteristics of 179 SFTS patients, we found that an elevated level of neurologic symptoms, respiratory symptoms, viral load, and a lower level of monocyte percentage were the critical risk factors for mortality. We used the 4 variables to assemble a score formula named the SFTS index [SFTSI = 5 × Neurologic symptoms-level + 4 × Respiratory symptoms-level + 3 × LG10 Viral load - 2 × LN Monocyte% - 7]. The AURC of this model was 0.964, which was higher than the AURC 0.913 of the viral load especially among the patients with higher viral loads (0.936 vs 0.821). We identified that the neurologic symptoms, respiratory symptoms, viral load, and monocyte percentage were the critical risk factors for SFTS mortality. The clinical score model of SFTSI provides a practical method for clinicians to stratify patients with SFTS and to adopt prompt effective treatment strategies.