Divergent trajectories of antiviral memory after SARS-CoV-2 infection.

The trajectories of acquired immunity to severe acute respiratory syndrome coronavirus 2 infection are not fully understood. We present a detailed longitudinal cohort study of UK healthcare workers prior to vaccination, presenting April-June 2020 with asymptomatic or symptomatic infection. Here we show a highly variable range of responses, some of which (T cell interferon-gamma ELISpot, N-specific antibody) wane over time, while others (spike-specific antibody, B cell memory ELISpot) are stable. We use integrative analysis and a machine-learning approach (SIMON - Sequential Iterative Modeling OverNight) to explore this heterogeneity. We identify a subgroup of participants with higher antibody responses and interferon-gamma ELISpot T cell responses, and a robust trajectory for longer term immunity associates with higher levels of neutralising antibodies against the infecting (Victoria) strain and also against variants B.1.1.7 (alpha) and B.1.351 (beta). These variable trajectories following early priming may define subsequent protection from severe disease from novel variants.

Comprehensive Comparative Analysis of Standard Validated, Genetic, and Novel Biomarkers to Enhance Prognostic Risk-Stratification in Patients With Hepatitis C Virus Cirrhosis.

INTRODUCTION: Risk-stratifying patients with hepatitis C virus (HCV) cirrhosis according to medium-term prognosis will inform clinical decision-making. It is unclear which biomarkers/models are optimal for this purpose. We quantified the discriminative ability of 14 diverse biomarkers for prognosis prediction over a 4-year time. METHODS: We recruited 1196 patients with HCV cirrhosis from the United Kingdom for a prospective study. Genetic risk score, collagen (e.g., PROC3), comorbidity (e.g., CirCom), and validated biomarkers from routine data were measured at enrollment. Participants were linked to UK hospital admission, cancer, and mortality registries. Primary endpoints were (i) liver-related outcomes for patients with compensated cirrhosis and (ii) all-cause mortality for decompensated cirrhosis. The discriminative ability of all biomarkers was quantified individually and also by the fraction of new prognostic information provided. RESULTS: At enrollment, 289 (24%) and 907 (76%) had decompensated and compensated cirrhosis, respectively. Participants were followed for 3-4 years on average, with >70% of the follow-up time occurring post-HCV cure. Seventy-five deaths in the decompensated subgroup and 98 liver-related outcomes in the compensated subgroup were reported. The discriminative ability of the albumin-bilirubin-fibrosis-4 index (C-index: 0.71-0.72) was superior to collagen biomarkers (C-index = 0.58-0.67), genetic risk scores (C-index = 0.50-0.57), and comorbidity markers (0.53-0.60). Validated biomarkers showed the greatest prognostic improvement when combined with a comorbidity or a collagen biomarker (generally >30% of new prognostic information added). DISCUSSION: Inexpensive biomarkers such as the albumin-bilirubin-fibrosis-4 index predict medium-term cirrhosis prognosis moderately well and outperform collagen, genetic, and comorbidity biomarkers. Improvement of performance was greatest when a validated test was combined with comorbidity or collagen biomarker.