Long-term use of tenofovir disoproxil fumarate increases fracture risk in elderly patients with chronic hepatitis B.

BACKGROUND & AIMS: The use of tenofovir disoproxil fumarate (TDF) is associated with a reduction in bone mineral density and an increase in bone metabolism biomarkers. However, data on clinical bone fractures remain limited. We evaluated the impact of TDF compared to entecavir on the risk of fracture in elderly patients with chronic hepatitis B (CHB). METHODS: Patients with CHB aged ≥60 years receiving entecavir or TDF between January 2008 and December 2022 were identified using a territory-wide database in Hong Kong. The risk of incident fracture in entecavir- and TDF-treated patients before and after month 24 were compared after propensity score matching. RESULTS: A total of 41,531 patients with CHB (mean age 69.8±7.8 years, 61.6% male) receiving entecavir (n = 39,897 [96.1%]) and TDF (n = 1,634 [3.9%]) were analysed. At a median follow-up of 25.3 (9.1-58.5) months, 1,733 (4.2%) patients developed incident fracture. Patients with incident fracture were more likely to have diabetes, hypertension, congestive heart failure, rheumatoid arthritis, osteoporosis, and a history of fracture. Compared with propensity score-matched entecavir-treated patients, the risk of incident fracture in TDF-treated patients was comparable in the first 24 months (weighted subdistribution hazard ratio [sHR] 0.99, 95% CI 0.56-1.73, p = 0.960) but increased after month 24 (weighted sHR 1.80, 95% CI 1.11-2.93, p = 0.019). The 24-, 60-, and 96-month cumulative incidences (95% CI) of fracture in TDF-treated and entecavir-treated patients were 2.3% (1.6%-3.4%) vs. 2.6% (1.9%-3.5%), 6.4% (5.0%-8.2%) vs. 4.7% (3.8%-6.0%), and 10.2% (8.3%-12.6%) vs. 6.8% (5.4%-8.5%), respectively. CONCLUSIONS: The risk of fracture increased with TDF treatment for ≥24 months in elderly patients with CHB. Selection of nucleos(t)ide analogues should be individualised based on age and comorbidities. IMPACT AND IMPLICATIONS: Previous literature suggested that the use of tenofovir disoproxil fumarate (TDF) is associated with a decrease in bone mineral density. However, data on the impact of TDF on long-term incident clinical fracture remains scarce. In this real-world territory-wide study of 41,531 treated patients with chronic hepatitis B in Hong Kong, patients who received TDF were at a higher risk of fracture after 2 years of treatment than those who received entecavir. Given the ageing population of patients with chronic hepatitis B and the rising prevalence of comorbidities, our findings support the current treatment guidelines that recommend selecting antiviral treatment based on age and comorbidities.

Incidence, epidemiology, and outcomes of acute allograft rejection following liver transplantation in Australia.

Acute allograft rejection is a well-known complication of liver transplantation (LT). The incidence, epidemiology, and outcomes of acute rejection have not been well described in Australia. We retrospectively studied consecutive adults who underwent deceased donor LT at a single center between 2010 and 2020. Donor and recipient data at the time of LT and recipient outcomes were collected from a prospective LT database. Liver biopsy reports were reviewed, and only a graft's first instance of biopsy-proven acute rejection was analyzed. During the study period, 796 liver transplants were performed in 770 patients. Biopsy-proven rejection occurred in 34.9% of transplants. There were no significant changes in the incidence of rejection over time (linear trend p =0.11). The median time to the first episode of rejection was 71 days after LT: 2.2% hyperacute, 50.4% early (≤90 d), and 47.5% late rejection (>90 d). Independent risk factors for rejection were younger recipient age at transplant (aHR 0.98 per year increase, 95% CI: 0.97-1.00, p =0.01), and ABO-incompatible grafts (aHR 2.55 vs. ABO-compatible, 95% CI: 1.27-5.09, p <0.01) while simultaneous multiorgan transplants were protective (aHR 0.21 vs. LT only, 95% CI: 0.08-0.58, p <0.01). Development of acute rejection (both early and late) was independently associated with significantly reduced graft (aHR 3.13, 95% CI: 2.21-4.42, p <0.001) and patient survival (aHR 3.42, 95% CI: 2.35-4.98, p <0.001). In this 11-year Australian study, acute LT rejection occurred in 35%, with independent risk factors of younger recipient age and ABO-incompatible transplant, while having a simultaneous multiorgan transplant was protective. Acute rejection was independently associated with reduced graft and patient survival after adjustment for other factors.

A pilot integrated model nurse clinic increases the uptake of antiviral treatment for the prevention of mother-to-child transmission of HBV.

BACKGROUND AND AIMS: Mother-to-child-transmission (MTCT) of hepatitis B virus (HBV) may still occur despite birth-dose HBV vaccinations when pregnant women are positive for hepatitis B surface antigen (HBsAg) with high viral loads (HBV DNA ≥ 200 000 IU/mL). A pilot integrated model nurse clinic (IMNC) was started in 2020 to implement the pre-emptive antiviral therapy with tenofovir disoproxil fumarate (TDF). We aimed to evaluate the performance of IMNC on uptake of TDF. METHODS: This was a territory-wide retrospective cohort of all consecutive HBsAg-positive women of child-bearing age with pregnancy records in public hospitals 2019-2022. Demographic characteristics, liver biochemistries and virologic parameters, and TDF use were collected. Concurrently, data from a prospective audit in Union Hospital, the private hospital with the highest number of deliveries in Hong Kong, from June 2022 to May 2023 were compared. RESULTS: The prevalence rate of HBV DNA ≥ 200 000 IU/mL in pregnant women with available HBV DNA records was 29.2% (66/226) in 2019, 27.3% (99/363) in 2020, 15.9% (125/784) in 2021 and 17.2% (117/679) in 2022 (p < .001), out of 2052 pregnant women who had their HBV DNA checked within 1 year prior to delivery. An increasing uptake rate of TDF by highly viraemic pregnant women (i.e. ≥ 200 000 IU/mL) was noted after the commencement of IMNC in public hospitals, with 67% (45/67) in 2019, 83% (88/106) in 2020, 91% (117/128) in 2021 and 89% (149/167) in 2022. Moreover, all highly viraemic pregnant women from Union Hospital received TDF. Continuous use of TDF was associated with a reduced risk of postpartum biochemical flare. CONCLUSIONS: IMNC increases the uptake of antiviral treatment in pregnant women at risk of MTCT of HBV. IMNC contributes to hepatitis elimination through a structured care plan to prevent MTCT of HBV.

Bacterial infections in patients with COVID-19: the impact of procalcitonin testing on antibiotics prescription in the real world.

BACKGROUND: Bacterial infections are not prevalent among patients hospitalized with COVID-19, while unnecessary prescription of antibiotics was commonly observed. This study aimed to determine the impact of procalcitonin testing on antibiotics prescription in the real-world setting. METHODS: We performed a territory-wide retrospective cohort study involving all laboratory-confirmed patients hospitalized in public hospitals in Hong Kong in 2020 with COVID-19. We determined the prevalence of bacterial co-infections (documented infections within 72 h of admission) and secondary bacterial infections (infections after 72 h of admission) and antibiotics consumption, and the correlation between procalcitonin testing and antibiotics prescription. RESULTS: The cohort included 8666 patients, with mean age 45.3 ± 19.9 years, 48.5% male, and comorbidities in 26.9%. Among 2688 patients with bacterial cultures performed, 147 (5.5%) had bacterial co-infections, and 222 (8.3%) had secondary bacterial infections. Antibiotics were prescribed for 2773 (32.0%) patients during the hospital admission. Procalcitonin tests were performed for 2543 (29.3%) patients. More patients with procalcitonin testing received antibiotics (65.9% vs. 17.9%, p < 0.001). Procalcitonin testing was associated with 5-fold increased risk of antibiotics prescription after adjusting for confounding variables. At hospital level, procalcitonin testing correlated with antibiotics prescription. Patients with procalcitonin level < 0.5 ng/mL had a lower probability of antibiotics initiation and shorter duration of antibiotics therapy. CONCLUSIONS: Procalcitonin testing was not associated with lower prescription of antibiotics. Patients with low procalcitonin level had lower antibiotics exposure, supporting the use of procalcitonin to exclude bacterial infections aiding early stopping of antibiotics among patients hospitalized with COVID-19.

Impact of the Use of Oral Antiviral Agents on the Risk of Hospitalization in Community Coronavirus Disease 2019 Patients (COVID-19).

BACKGROUND: We examined the effectiveness of molnupiravir and nirmatrelvir/ritonavir in reducing hospitalization and deaths in a real-world cohort of nonhospitalized patients with coronavirus disease 2019 (COVID-19). METHODS: This was a territory-wide retrospective cohort study in Hong Kong. Nonhospitalized COVID-19 patients who attended designated outpatient clinics between 16 February and 31 March 2022 were identified. Patients hospitalized on the day of the first clinic appointment or used both oral antivirals were excluded. The primary endpoint was hospitalization. The secondary endpoint was a composite of intensive care unit admission, invasive mechanical ventilation use, and/or death. RESULTS: Of 93 883 patients, 83 154 (88.6%), 5808 (6.2%), and 4921 (5.2%) were oral antiviral nonusers, molnupiravir users, and nirmatrelvir/ritonavir users, respectively. Compared with nonusers, oral antiviral users were older and had more comorbidities, lower complete vaccination rate, and more hospitalizations in the previous year. Molnupiravir users were older and had more comorbidities, lower complete vaccination rate, and more hospitalizations in the previous year than nirmatrelvir/ritonavir users. At a median follow-up of 30 days, 1931 (2.1%) patients were hospitalized and 225 (0.2%) patients developed the secondary endpoint. After propensity score weighting, nirmatrelvir/ritonavir use (weighted hazard ratio 0.79; 95% confidence interval [CI], 0.65-0.95; P = .011) but not molnupiravir use (weighted hazard ratio 1.17; 95% CI, 0.99-1.39; P = .062) was associated with a reduced risk of hospitalization than nonusers. The use of molnupiravir or nirmatrelvir/ritonavir was not associated with a lower risk of the secondary endpoint as compared with nonusers. CONCLUSION: Use of nirmatrelvir/ritonavir but not molnupiravir was associated with a reduced risk of hospitalization in real-world nonhospitalized patients with COVID-19.

Risk of hepatic decompensation but not hepatocellular carcinoma decreases over time in patients with hepatitis B surface antigen loss.

BACKGROUND & AIMS: We examined the long-term incidence of hepatocellular carcinoma (HCC) and hepatic decompensation among chronic hepatitis B (CHB) patients who have achieved hepatitis B surface antigen (HBsAg) seroclearance. METHODS: All adult CHB-monoinfected patients who cleared HBsAg between January 2000 and December 2020 were identified using a territory-wide database in Hong Kong. Patients who underwent liver transplantation and/or developed HCC before HBsAg seroclearance or less than 6 months follow-up were excluded. The primary and secondary endpoints were HCC and hepatic decompensation respectively. RESULTS: We identified 9,769 patients with CHB who achieved HBsAg seroclearance (mean age 57 years, 60.0% male, 13.2% cirrhosis); most had compensated liver function at HBsAg loss. At a median (25th-75th percentile) follow-up of 4.6 (2.2-8.4) years, 106 (1.1%) patients developed HCC. Patients who developed HCC were older, more likely to be male and have cirrhosis, and had higher alanine aminotransferase and lower platelets at the time of HBsAg loss than patients without HCC. The cumulative incidence of HCC remained steady 0-7 and 8-12 years after HBsAg loss (p = 0.898) (crude annual incidence drop: -0.04%, 95% CI -0.13% to 0.04%, p = 0.265). Moreover, 124/9,640 (1.3%) patients developed hepatic decompensation. The growth in cumulative incidence of hepatic decompensation decelerated 8-12 years after HBsAg loss (p = 0.009) (crude annual incidence drop: -0.23%, 95% CI -0.40% to -0.06%, p = 0.012). In multivariable analysis, HBsAg loss for over 7 years was associated with a reduced risk of hepatic decompensation (adjusted subdistribution hazard ratio [aSHR] 0.55, 95% CI 0.31-0.97, p = 0.039) but not HCC (aSHR 1.35, 95% CI 0.83-2.19, p = 0.230). CONCLUSION: HCC risk persists in patients after HBsAg loss, whereas the risk of hepatic decompensation decreases over time. IMPACT AND IMPLICATIONS: Patients with chronic hepatitis B (CHB) still have a non-negligible risk of hepatocellular carcinoma (HCC) after 12 years of HBsAg seroclearance, especially among those with cirrhosis. The risk of developing hepatic decompensation decreases over time after HBsAg seroclearance. In clinical practice, although patients with CHB who cleared HBsAg have a more favourable clinical outcome than those who remain chronically infected, long-term HCC surveillance would still be necessary for patients with cirrhosis and other high-risk subgroups after HBsAg seroclearance.

Diabetes Mellitus Impacts on the Performance of Hepatocellular Carcinoma Risk Scores in Chronic Hepatitis B Patients.

BACKGROUND & AIMS: We examined whether changing clinical characteristics and presence of diabetes mellitus (DM) impact the performance of hepatocellular carcinoma (HCC) risk scores. METHODS: Adult patients with chronic hepatitis B (CHB) on ≥6 months of entecavir/tenofovir treatment between January 2005 and March 2020 were identified using a territory-wide electronic database in Hong Kong. DM was defined by antidiabetic agents, hemoglobin A1c ≥6.5%, fasting glucose ≥7 mmol/L, and/or diagnosis codes. PAGE-B, modified PAGE-B (mPAGE-B), and aMAP scores were assessed by area under the time-dependent receiver operating characteristic curves (AUROCs) and compared with CAMD and REAL-B scores with DM as a component. RESULTS: Of 48,706 patients, 2792, 11,563, 15,471, and 18,880 started entecavir/tenofovir treatment between 2005-2008, 2009-2012, 2013-2016, and 2017-2020, respectively; DM prevalence rose from 15.5% in 2005-2008 to 24.3% in 2017-2020. AUROCs were comparable across the 4 periods in the 5 HCC risk scores (AUROCs ranged between 0.75 and 0.81). At a median follow-up of 4.4 years, 1512 non-diabetic (4.0%) and 645 (6.2%) diabetic patients developed HCC. AUROCs of all 5 scores were lower in diabetic patients than in non-diabetic patients (AUROCs ranged between 0.67-0.71 vs 0.78-0.82; all P < .001). REAL-B score achieved an AUROC of 0.71 in diabetic and 0.82 in non-diabetic patients. Both diabetic and non-diabetic patients in the low-risk group by REAL-B score had a low HCC incidence below the threshold of cost-effective HCC surveillance, ie, 0.2% annually. CONCLUSIONS: REAL-B score is accurate and preferred in entecavir/tenofovir-treated CHB patients because of the increasing prevalence of DM.

Baveno VII criteria for recompensation predict transplant-free survival in patients with hepatitis B-related decompensated cirrhosis.

Background & Aims: The latest Baveno VII consensus has provided guidance for identifying patients who have truly recompensated from those with hepatic decompensation. This study aimed to evaluate patients' transplant-free survival in three different stages of cirrhosis. Methods: All patients with chronic HBV infection and liver cirrhosis treated with oral nucleos(t)ide analogues from March 2006 to December 2022 were identified from a territory-wide database in Hong Kong. Patients with follow-up duration of <1 year were excluded. Participants were classified into three mutually exclusive groups: (1) no decompensated events (i.e. compensated group); (2) decompensated events occurred (i.e. decompensated group); or (3) decompensated events occurred followed by recompensation according to Baveno VII criteria (i.e. recompensated group). A time-dependent Cox proportional hazard model was adopted for evaluation. The follow-up period was 5 years. Results: A total of 4,701 patients with cirrhosis and HBV who were treated with entecavir, tenofovir disoproxil fumarate (TDF), and tenofovir alafenamide fumarate (TAF) were identified. During a median follow-up of 5 years (interquartile range 3.7, 5 years), 3,327 (70.8%), 1,347 (29.2%), and 265 (5.6%) patients had compensated, decompensated, and recompensated cirrhosis, respectively, at least once before the end of the study. In the time-dependent multivariable model, the recompensated group had similar transplant-free survival compared with the compensated group (adjusted hazard ratio 1.16; 95% CI 0.72-1.86; p = 0.536). The 5-year transplant-free survival rate was 89.3% for the compensated group, whereas it was 76.0% for the recompensated group, reflecting a minimal difference between the two groups. Conclusions: The clinical significance of recompensation of cirrhosis in improving patient outcomes for individuals with CHB infection was highlighted in this study. Early identification and treatment with nucleos(t)ide analogues might promote hepatic recompensation and thus reduce mortality in patients with CHB. Impact and implications: The latest Baveno VII consensus introduces the new concept of hepatic recompensation, which refers to the reversal of the structural and functional changes of cirrhosis after removal, cure, or suppression of the aetiology of cirrhosis. It is essential to investigate the transplant-free survival rates of patients who are able to achieve hepatic recompensation, as this has significant implications for the medical resources required to manage liver failure and transplantation. This study features the clinical significance of hepatic recompensation by comparing patient outcomes of those who achieve it to those who do not. The early identification and use of antiviral treatment with nucleos(t)ide analogues is a pivotal strategy to promote hepatic recompensation, which has the potential to significantly reduce mortality rates in patients with chronic HBV infection and ultimately aid in the elimination of hepatitis.

Clinical Outcomes Following Treatment for COVID-19 With Nirmatrelvir/Ritonavir and Molnupiravir Among Patients Living in Nursing Homes.

Importance: Older patients living in nursing homes are at very high risk of mortality after getting COVID-19. Objective: To evaluate outcomes following oral antiviral treatment for COVID-19 among nonhospitalized older patients living in nursing homes. Design, Setting, and Participants: This is a territory-wide, retrospective cohort study conducted between February 16 and March 31, 2022, with the last follow-up date on April 25, 2022. Participants were patients with COVID-19 living in nursing homes in Hong Kong. Data analysis was performed from May to June 2022. Exposures: Molnupiravir, nirmatrelvir/ritonavir, or no oral antiviral treatment. Main Outcomes and Measures: The primary outcome was hospitalization for COVID-19, and the secondary outcome was risk of inpatient disease progression (ie, admission to intensive care unit, use of invasive mechanical ventilation, and/or death). Results: Of 14 617 patients (mean [SD] age, 84.8 [10.2] years; 8222 women [56.2%]), 8939 (61.2%) did not use oral antivirals, 5195 (35.5%) used molnupiravir, and 483 (3.3%) used nirmatrelvir/ritonavir. Compared with patients who did not use oral antivirals, those who used molnupiravir and nirmatrelvir/ritonavir were more likely to be female and less likely to have comorbid illnesses and hospitalization in the past year. At a median (IQR) follow-up of 30 (30-30) days, 6223 patients (42.6%) were hospitalized and 2307 patients (15.8%) experienced inpatient disease progression. After propensity score weighting, both molnupiravir and nirmatrelvir/ritonavir were associated with a reduced risk of hospitalization (molnupiravir, weighted hazard ratio [wHR], 0.46; 95% CI, 0.37-0.57; P < .001; nirmatrelvir/ritonavir, wHR, 0.46; 95% CI, 0.32-0.65; P < .001) and inpatient disease progression (molnupiravir, wHR, 0.35; 95% CI, 0.23-0.51; P < .001; nirmatrelvir/ritonavir, wHR, 0.17; 95% CI, 0.06-0.44; P < .001). Nirmatrelvir/ritonavir was comparable to molnupiravir in achieving better clinical outcomes (hospitalization, wHR, 1.00; 95% CI, 0.75-1.33; P = .99; inpatient disease progression, wHR, 0.49; 95% CI, 0.20-1.20; P = .12). Conclusions and Relevance: In this retrospective cohort study, the use of oral antivirals to treat COVID-19 was associated with a reduced risk of hospitalization and inpatient disease progression among patients living in nursing homes. The findings of this study of nursing home residents could be reasonably extrapolated to other frail older patients living in the community.

Trends in risk factor control and treatment among patients with non-alcoholic fatty liver disease and type 2 diabetes between 2000 and 2020: A territory-wide study.

BACKGROUND & AIMS: We aimed to determine the trends in risk factor control and treatment among patients with non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D) in 2000-2020. METHODS: We conducted a territory-wide cohort study of adult patients with NAFLD and T2D diagnosed between 1 January 2000 and 31 July 2021 in Hong Kong. T2D was defined by use of any anti-diabetic agents, laboratory tests and/or diagnosis codes. RESULTS: This study included 16,084 patients with NAFLD and T2D (mean age, 54.8 ± 12.0 years; 7124 male [44.3%]). The percentage of patients achieving individualised haemoglobin A1c (HbA1c ) targets increased from 44.5% (95% confidence interval [CI], 42.9-46.1) to 64.8% (95% CI, 64.1-65.5), and percentage of patients achieving individualised low-density lipoprotein-cholesterol (LDL-C) targets increased from 23.3% (95% CI, 21.9-24.7) to 54.3% (95% CI, 53.5-55.1) from 2000-2005 to 2016-2020, whereas percentage of patients achieving blood pressure control (<140/90 mm Hg) remained static at 53.1-57.2%. Combination therapy for diabetes increased, especially among those with poor glycaemic control, but there was no increase in combination therapy for hypertension. Fewer cirrhotic patients achieved blood pressure control and individualised LDL-C targets, but they were more likely to achieve individualised HbA1c targets than non-cirrhotics. Metformin and statins were underused in cirrhotic patients. Younger patients (18-44 years) were less likely to achieve individualised HbA1c targets than middle-aged (45-64 years) and older ones (≥65 years). CONCLUSIONS: From 2000 to 2020, glycaemic and lipid control improved significantly, whereas blood pressure control remained static among patients with NAFLD and T2D.

Resilient Hippocampal Gamma Rhythmogenesis and Parvalbumin-Expressing Interneuron Function Before and After Plaque Burden in 5xFAD Alzheimer's Disease Model.

Recent studies have implicated impaired Parvalbumin Fast-Spiking Interneuron (PVIN) function as a precipitating factor underlying abnormalities in network synchrony, oscillatory rhythms, and cognition associated with Alzheimer's disease (AD). However, a complete developmental investigation of potential gamma deficits, induced by commonly used carbachol or kainate in ex vivo slice preparations, within AD model mice is lacking. We examined gamma oscillations using field recordings in acute hippocampal slices from 5xFAD and control mice, through the period of developing pathology, starting at 3 months of age, when there is minimal plaque presence in the hippocampus, through to 12+ months of age, when plaque burden is high. In addition, we examined PVIN participation in gamma rhythms using targeted cell-attached recordings of genetically-reported PVINs, in both wild type and mutant mice. In parallel, a developmental immunohistochemical characterisation probing the PVIN-associated expression of PV and perineuronal nets (PNNs) was compared between control and 5xFAD mice. Remarkably, this comprehensive longitudinal evaluation failed to reveal any obvious correlations between PVIN deficits (electrical and molecular), circuit rhythmogenesis (gamma frequency and power), and Aß deposits/plaque formation. By 6-12 months, 5xFAD animals have extensive plaque formation throughout the hippocampus. However, a deficit in gamma oscillatory power was only evident in the oldest 5xFAD animals (12+ months), and only when using kainate, and not carbachol, to induce the oscillations. We found no difference in PV firing or phase preference during kainate-induced oscillations in younger or older 5xFAD mice compared to control, and a reduction of PV and PNNs only in the oldest 5xFAD mice. The lack of a clear relationship between PVIN function, network rhythmicity, and plaque formation in our study highlights an unexpected resilience in PVIN function in the face of extensive plaque pathology associated with this model, calling into question the presumptive link between PVIN pathology and Alzheimer's progression.

Incidence of Viral Rebound After Treatment With Nirmatrelvir-Ritonavir and Molnupiravir.

Importance: Some patients treated with nirmatrelvir-ritonavir have experienced rebound of COVID-19 infections and symptoms; however, data are scarce on whether viral rebound also occurs in patients with COVID-19 receiving or not receiving molnupiravir. Objective: To examine the incidence of viral rebound in patients with COVID-19 who were treated with the oral antiviral agents nirmatrelvir-ritonavir and molnupiravir. Design, Setting, and Participants: This cohort study identified 41 255 patients with COVID-19 who were hospitalized from January 1, 2022, to March 31, 2022, in Hong Kong and assessed 12 629 patients with serial cycle threshold (Ct) values measured. Patients were followed up until the occurrence of the clinical end point of interest, death, date of data retrieval (July 31, 2022), or up to 30 days of follow-up, whichever came first. Exposures: Molnupiravir or nirmatrelvir-ritonavir treatment. Main Outcomes and Measures: Viral rebound, defined as a Ct value greater than 40 that decreased to 40 or less. Results: Of 12 629 patients (mean [SD] age, 65.4 [20.9] years; 6624 [52.5%] male), 11 688 (92.5%) were oral antiviral nonusers, 746 (5.9%) were molnupiravir users, and 195 (1.5%) were nirmatrelvir-ritonavir users. Compared with nonusers, oral antiviral users were older, had more comorbidities, and had lower complete vaccination rates. The mean (SD) baseline Ct value was slightly higher in nirmatrelvir-ritonavir users (22.2 [6.0]) than nonusers (21.0 [5.4]) and molnupiravir users (20.9 [5.4]) (P = .04). Viral rebound occurred in 68 nonusers (0.6%), 2 nirmatrelvir-ritonavir users (1.0%), and 6 molnupiravir users (0.8%). Among 76 patients with viral rebound, 12 of 68 nonusers, 1 of 6 molnupiravir users, and neither of the nirmatrelvir-ritonavir users died of COVID-19. Conclusions and Relevance: In this cohort study, viral rebound was uncommon in patients taking molnupiravir or nirmatrelvir-ritonavir and was not associated with increased risk of mortality. Given these findings, novel oral antivirals should be considered as a treatment for more patients with COVID-19 in the early phase of the infection.

Activity-dependent tuning of intrinsic excitability in mouse and human neurogliaform cells.

The ability to modulate the efficacy of synaptic communication between neurons constitutes an essential property critical for normal brain function. Animal models have proved invaluable in revealing a wealth of diverse cellular mechanisms underlying varied plasticity modes. However, to what extent these processes are mirrored in humans is largely uncharted thus questioning their relevance in human circuit function. In this study, we focus on neurogliaform cells, that possess specialized physiological features enabling them to impart a widespread inhibitory influence on neural activity. We demonstrate that this prominent neuronal subtype, embedded in both mouse and human neural circuits, undergo remarkably similar activity-dependent modulation manifesting as epochs of enhanced intrinsic excitability. In principle, these evolutionary conserved plasticity routes likely tune the extent of neurogliaform cell mediated inhibition thus constituting canonical circuit mechanisms underlying human cognitive processing and behavior.

Paradoxical network excitation by glutamate release from VGluT3+ GABAergic interneurons.

In violation of Dale's principle several neuronal subtypes utilize more than one classical neurotransmitter. Molecular identification of vesicular glutamate transporter three and cholecystokinin expressing cortical interneurons (CCK+VGluT3+INTs) has prompted speculation of GABA/glutamate corelease from these cells for almost two decades despite a lack of direct evidence. We unequivocally demonstrate CCK+VGluT3+INT-mediated GABA/glutamate cotransmission onto principal cells in adult mice using paired recording and optogenetic approaches. Although under normal conditions, GABAergic inhibition dominates CCK+VGluT3+INT signaling, glutamatergic signaling becomes predominant when glutamate decarboxylase (GAD) function is compromised. CCK+VGluT3+INTs exhibit surprising anatomical diversity comprising subsets of all known dendrite targeting CCK+ interneurons in addition to the expected basket cells, and their extensive circuit innervation profoundly dampens circuit excitability under normal conditions. However, in contexts where the glutamatergic phenotype of CCK+VGluT3+INTs is amplified, they promote paradoxical network hyperexcitability which may be relevant to disorders involving GAD dysfunction such as schizophrenia or vitamin B6 deficiency.

Fear Learning Regulates Cortical Sensory Representations by Suppressing Habituation.

Projections from auditory cortex to the amygdala are thought to contribute to the induction of auditory fear learning. In addition, fear conditioning has been found to enhance cortical responses to conditioned tones, suggesting that cortical plasticity contributes to fear learning. However, the functional role of auditory cortex in the retrieval of fear memories is unclear and how fear learning regulates cortical sensory representations is not well understood. To address these questions, we use acute optogenetic silencing and chronic two-photon calcium imaging in mouse auditory cortex during fear learning. Longitudinal imaging of neuronal ensemble activity reveals that discriminative fear learning modulates cortical sensory representations via the suppression of cortical habituation.