Computational prediction of interactions between Paxlovid and prescription drugs.

Pfizer's Paxlovid has recently been approved for the emergency use authorization (EUA) from the US Food and Drug Administration (FDA) for the treatment of mild-to-moderate COVID-19. Drug interactions can be a serious medical problem for COVID-19 patients with underlying medical conditions, such as hypertension and diabetes, who have likely been taking other drugs. Here, we use deep learning to predict potential drug-drug interactions between Paxlovid components (nirmatrelvir and ritonavir) and 2,248 prescription drugs for treating various diseases.

Azvudine versus Paxlovid in COVID-19: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to compare the effectiveness and safety of azvudine versus nirmatrelvir/ritonavir (Paxlovid) in treating coronavirus disease 2019 (COVID-19). The researchers conducted searches on PubMed, Cochrane Library, Web of Science, medRxiv, and Google Scholar until January 2024. The Cochrane risk of bias tool was utilised to evaluate the quality of the included studies, and data analysis was performed using Comprehensive Meta-Analysis software. Thirteen studies, including 4949 patients, were analysed. The meta-analysis results showed no significant difference between the azvudine and Paxlovid groups in terms of mortality rate (odds rate [OR] = 0.84, 95% confidence interval [CI]: 0.59-1.21), negative polymerase chain reaction (PCR) conversion time (standard mean difference [SMD] = 1.52, 95% CI: -1.07-4.11), and hospital stay (SMD = -0.39, 95% CI: -1.12-0.33). However, a significant difference was observed between the two groups in terms of intensive care unit admission (OR = 0.42, 95% CI: 0.23-0.75) and the need for mechanical ventilation (OR = 0.61, 95% CI: 0.44-0.86) in favour of azvudine. The incidence of adverse events in the azvudine group was significantly lower (OR = 0.66, 95% CI: 0.43-0.99). The certainty of evidence was rated as low and moderate. Azvudine and Paxlovid demonstrated similar effectiveness in reducing mortality rates, negative PCR conversion time and hospital stay. However, azvudine showed better effectiveness in improving other outcomes. Regarding the level of certainty of evidence, further research is needed to validate or challenge these results.

Structural basis of nirmatrelvir and ensitrelvir activity against naturally occurring polymorphisms of the SARS-CoV-2 main protease.

SARS-CoV-2 is the causative agent of COVID-19. The main viral protease (Mpro) is an attractive target for antivirals. The clinically approved drug nirmatrelvir and the clinical candidate ensitrelvir have so far showed great potential for treatment of viral infection. However, the broad use of antivirals is often associated with resistance generation. Herein, we enzymatically characterized 14 naturally occurring Mpro polymorphisms that are close to the binding site of these antivirals. Nirmatrelvir retained its potency against most polymorphisms tested, while mutants G143S and Q189K were associated with diminished inhibition constants. For ensitrelvir, diminished inhibition constants were observed for polymorphisms M49I, G143S, and R188S, but not for Q189K, suggesting a distinct resistance profile between inhibitors. In addition, the crystal structures of selected polymorphisms revealed interactions that were critical for loss of potency. In conclusion, our data will assist the monitoring of potential resistant strains, support the design of combined therapy, as well as assist the development of the next generation of Mpro inhibitors.

Identifying Veterans Who Benefit From Nirmatrelvir-Ritonavir: A Target Trial Emulation.

BACKGROUND: Nirmatrelvir-ritonavir is recommended for persons at risk for severe coronavirus disease 2019 (COVID-19) but remains underutilized. Information on which eligible groups are likely to benefit from treatment is needed. METHODS: We conducted a target trial emulation study in the Veterans Health Administration comparing nirmatrelvir-ritonavir treated versus matched untreated veterans at risk for severe COVID-19 who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from April 2022 through March 2023. We measured incidence of any hospitalization or all-cause mortality at 30 days. Outcomes were measured for the entire cohort, as well as among subgroups defined by 30-day risk of death or hospitalization, estimated using an ensemble risk prediction model. RESULTS: Participants were 87% male with median age 66 years and 16% unvaccinated. Compared with matched untreated participants, those treated with nirmatrelvir-ritonavir (n = 24 205) had a lower 30-day risk for hospitalization (1.80% vs 2.30%; risk difference [RD], -0.50% points [95% confidence interval {CI}: -.69 to -.35]) and death (0.11% vs 0.30%; RD, -0.20 [95% CI: -.24 to -.13]). The greatest reductions in combined hospitalization or death were observed in the highest risk quartile (RD -2.85 [95% CI: -3.94 to -1.76]), immunocompromised persons (RD -1.91 [95% CI: -3.09 to -.74]), and persons aged ≥75 years (RD -1.16 [95% CI: -1.73 to -.59]). No reductions were observed in the 2 lowest risk quartiles or persons younger than 65 years. CONCLUSIONS: Nirmatrelvir-ritonavir was effective in reducing 30-day hospitalization and death in older veterans, those at highest predicted risk for severe outcomes, and immunocompromised groups. Benefit was not observed in younger veterans or groups at lower predicted risk for hospitalization and death.

Public Health Impact of Paxlovid as Treatment for COVID-19, United States.

We evaluated the population-level benefits of expanding treatment with the antiviral drug Paxlovid (nirmatrelvir/ritonavir) in the United States for SARS-CoV-2 Omicron variant infections. Using a multiscale mathematical model, we found that treating 20% of symptomatic case-patients with Paxlovid over a period of 300 days beginning in January 2022 resulted in life and cost savings. In a low-transmission scenario (effective reproduction number of 1.2), this approach could avert 0.28 million (95% CI 0.03-0.59 million) hospitalizations and save US $56.95 billion (95% CI US $2.62-$122.63 billion). In a higher transmission scenario (effective reproduction number of 3), the benefits increase, potentially preventing 0.85 million (95% CI 0.36-1.38 million) hospitalizations and saving US $170.17 billion (95% CI US $60.49-$286.14 billion). Our findings suggest that timely and widespread use of Paxlovid could be an effective and economical approach to mitigate the effects of COVID-19.

Paxlovid use is associated with lower risk of cardiovascular diseases in COVID-19 patients with autoimmune rheumatic diseases: a retrospective cohort study.

BACKGROUND: Paxlovid has been shown to be effective in reducing mortality and hospitalization rates in patients with coronavirus disease 2019 (COVID-19). It is not known whether Paxlovid can reduce the risk of cardiovascular diseases (CVD) in COVID-19-surviving patients with autoimmune rheumatic diseases (AIRDs). METHODS: TriNetX data from the US Collaborative Network were used in this study. A total of 5,671,395 patients with AIRDs were enrolled between January 1, 2010, and December 31, 2021. People diagnosed with COVID-19 were included in the cohort (n = 238,142) from January 1, 2022, to December 31, 2022. The Study population was divided into two groups based on Paxlovid use. Propensity score matching was used to generate groups with matched baseline characteristics. The hazard ratios (HRs) and 95% confidence intervals of cardiovascular outcomes, admission rate, mortality rate, and intensive care unit (ICU) admission rate were calculated between Paxlovid and non-Paxlovid groups. Subgroup analyses on sex, age, race, autoimmune diseases group, and sensitivity analyses for Paxlovid use within the first day or within 2-5 days of COVID-19 diagnosis were performed. RESULTS: Paxlovid use was associated with lower risks of cerebrovascular complications (HR = 0.65 [0.47-0.88]), arrhythmia outcomes (HR = 0.81 [0.68-0.94]), ischemic heart disease, other cardiac disorders (HR = 0.51 [0.35-0.74]) naming heart failure (HR = 0.41 [0.26-0.63]) and deep vein thrombosis (HR = 0.46 [0.24-0.87]) belonging to thrombotic disorders in AIRD patients with COVID-19. Compared with the Non-Paxlovid group, risks of major adverse cardiac events (HR = 0.56 [0.44-0.70]) and any cardiovascular outcome mentioned above (HR = 0.76 [0.66-0.86]) were lower in the Paxlovid group. Moreover, the mortality (HR = 0.21 [0.11-0.40]), admission (HR = 0.68 [0.60-0.76]), and ICU admission rates (HR = 0.52 [0.33-0.80]) were significantly lower in the Paxlovid group than in the non-Paxlovid group. Paxlovid appears to be more effective in male, older, and Black patients with AIRD. The risks of cardiovascular outcomes and severe conditions were reduced significantly with Paxlovid prescribed within the first day of COVID-19 diagnosis. CONCLUSIONS: Paxlovid use is associated with a lower risk of CVDs and severe conditions in COVID-19-surviving patients with AIRD.

Association of nirmatrelvir for acute SARS-CoV-2 infection with subsequent Long COVID symptoms in an observational cohort study.

Oral nirmatrelvir/ritonavir is approved as treatment for acute COVID-19, but the effect of treatment during acute infection on risk of Long COVID is unknown. We hypothesized that nirmatrelvir treatment during acute SARS-CoV-2 infection reduces risk of developing Long COVID and rebound after treatment is associated with Long COVID. We conducted an observational cohort study within the Covid Citizen Science (CCS) study, an online cohort study with over 100 000 participants. We included vaccinated, nonhospitalized, nonpregnant individuals who reported their first SARS-CoV-2 positive test March-August 2022. Oral nirmatrelvir/ritonavir treatment was ascertained during acute SARS-CoV-2 infection. Patient-reported Long COVID symptoms, symptom rebound and test-positivity rebound were asked on subsequent surveys at least 3 months after SARS-CoV-2 infection. A total of 4684 individuals met the eligibility criteria, of whom 988 (21.1%) were treated and 3696 (78.9%) were untreated; 353/988 (35.7%) treated and 1258/3696 (34.0%) untreated responded to the Long COVID survey (n = 1611). Among 1611 participants, median age was 55 years and 66% were female. At 5.4 ± 1.3 months after infection, nirmatrelvir treatment was not associated with subsequent Long COVID symptoms (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.80-1.64; p = 0.45). Among 666 treated who answered rebound questions, rebound symptoms or test positivity were not associated with Long COVID symptoms (OR: 1.34; 95% CI: 0.74-2.41; p = 0.33). Within this cohort of vaccinated, nonhospitalized individuals, oral nirmatrelvir treatment during acute SARS-CoV-2 infection and rebound after nirmatrelvir treatment were not associated with Long COVID symptoms more than 90 days after infection.

Effectiveness of nirmatrelvir-ritonavir on severe outcomes of COVID-19 in the era of vaccination and Omicron: An updated meta-analysis.

Nirmatrelvir-ritonavir (NR) was approved to treat SARS-CoV-2 positive outpatients at high risk of progression to severe disease, based on a randomized trial in unvaccinated patients. Effectiveness in vaccinated patients and against Omicron has not yet been confirmed by clinical trial data, but a recent meta-analysis suggested good real-world effectiveness based on 12 studies. We updated this meta-analysis by searching Medline and Embase databases for studies assessing effectiveness of NR on mortality, hospitalization, composite outcome of hospitalization and/or death, and progression to severe disease, published between October 1, 2022 and May 22, 2023. Random effects meta-analysis and subgroup analysis for vaccinated patients was performed. A total of 32 studies were included in the meta-analysis. Pooled RR for the effect of NR on mortality, hospitalization, hospitalization and/or mortality, and progression to severe disease were 0.36 (95% confidence interval [CI]: 0.25-0.52), 0.43 (CI: 0.37-0.51), 0.52 (CI: 0.45-0.61) and 0.54 (CI: 0.41-0.73), respectively. A subgroup analysis on vaccinated patients indicated lower effectiveness of NR on mortality (RR: 0.55, CI: 0.45-0.68), but similar effectiveness for hospitalization, hospitalization and/or mortality, or progression to severe disease (RR: 0.52, 0.58, and 0.66, respectively). This updated meta-analysis robustly confirms the protective effects of NR on severe COVID-19 outcomes.

Nirmatrelvir/Ritonavir Regimen for Mild/Moderately Severe COVID-19: A Rapid Review With Meta-Analysis and Trial Sequential Analysis.

BACKGROUND: The efficacy, effectiveness, and safety of the approved nirmatrelvir/ritonavir regimen for treatment of laboratory-confirmed mild/moderately severe COVID-19 remains unclear. METHODS: We systematically identified randomized controlled trials (RCTs) and real-world studies (RWS; observational studies) of the efficacy/effectiveness and/or safety of the approved nirmatrelvir/ritonavir regimen for COVID-19. We pooled appropriate data (adjusted estimates for RWS) using an inverse variance, random-effects model. We calculated statistical heterogeneity using the I 2 statistic. Results are presented as relative risk (RR) with associated 95% CI. We further assessed risk of bias/study quality and conducted trial sequential analysis of the evidence from RCTs. RESULTS: We included 4 RCTs (4,070 persons) and 16 RWS (1,925,047 persons) of adults (aged ≥18 years). One and 3 RCTs were of low and unclear risk of bias, respectively. The RWS were of good quality. Nirmatrelvir/ritonavir significantly decreased COVID-19 hospitalization compared with placebo/no treatment (RR = 0.17; 95% CI, 0.10-0.31; I 2 = 77.2%; 2 RCTs, 3,542 persons), but there was no significant difference for decrease of worsening severity (RR = 0.82; 95% CI, 0.66-1.01; I 2 = 47.5%; 3 RCTs, 1,824 persons), viral clearance (RR = 1.19; 95% CI, 0.93-1.51; I 2 = 82%; 2 RCTs, 528 persons), adverse events (RR = 1.41; 95% CI, 0.92-2.14; I 2 = 70.6%; 4 RCTs, 4,070 persons), serious adverse events (RR = 0.82; 95% CI, 0.41-1.62; I 2 = 0%; 3 RCTs, 3,806 persons), and all-cause mortality (RR = 0.27; 95% CI, 0.04-1.70; I 2 = 49.9%; 3 RCTs, 3,806 persons), although trial sequential analysis suggested that the current total sample sizes for these outcomes were not large enough for conclusions to be drawn. Real-world studies also showed significantly decreased COVID-19 hospitalization (RR = 0.48; 95% CI, 0.37-0.60; I 2 = 95.0%; 11 RWS, 1,421,398 persons) and all-cause mortality (RR = 0.24; 95% CI, 0.14-0.34; I 2 = 65%; 7 RWS, 286,131 persons) for nirmatrelvir/ritonavir compared with no treatment. CONCLUSIONS: Nirmatrelvir/ritonavir appears to be promising for preventing hospitalization and potentially decreasing all-cause mortality for persons with mild/moderately severe COVID-19, but the evidence is weak. More studies are needed.

Appraisal of evidence reliability and applicability of Paxlovid as treatment for SARS-COV-2 infection: A systematic review.

This study aimed to clarify the beneficial effect and the clinical application value of Paxlovid in the treatment of coronavirus disease-19 (COVID-19) through a systematic review. Databases including PubMed, Cochrane Library, Chinese Clinical Trial Registry, and ClinicalTrials.gov were systematically searched for interventional or observational studies on the efficacy and safety of Paxlovid in the treatment of SARS-COV-2. The relative and absolute effect sizes for the outcomes were calculated based on the data reported in the original intervention literature. The external applicability of the evidence was analysed in terms of clinical application scenarios, patient willingness, and cost utility. One interventional and three observational studies were conducted. Four studies published in 2022, had participation sample sizes ranging 1780-109,254. Based on the randomised controlled trial data, the risk of all-cause mortality, all-cause death, and hospitalisation was significantly reduced in the Paxlovid group. Serious adverse events were reduced during the study. Based on observational studies, Paxlovid can significantly reduce the risk of death and hospitalisation in older patients with COVID-19 (moderate certainty) and improve in-hospital disease progression, composite disease progression, and viral load (low certainty). Paxlovid did not improve the outcomes of death and hospitalisation (low certainty) in patients aged <65 years. As per the economic utility analysis, the economic cost of reducing one death dramatically decreased with increasing age. Early use of Paxlovid in the older adult population with COVID-19 is beneficial. However, in the setting of limited resources, Paxlovid should be prioritised for older patients.

Efficacy and safety of paxlovid (nirmatrelvir/ritonavir) in the treatment of COVID-19: An updated meta-analysis and trial sequential analysis.

Our study is aimed to access the efficacy and safety outcomes for coronavirus disease 2019 (COVID-19) patients treated with Paxlovid. According to inclusion and exclusion criteria, databases were used to retrieve articles from 1 January 2020 to 1 January 2023. Article screening, quality evaluation and data extraction were completed and cross-checked. The meta-analysis and trial sequential analysis (TSA) were conducted using RevMan, StataMP, and TSA software. A total of 42 original articles were included. Overall meta-analysis results showed that for death, hospitalisation, death or hospitalisation, emergency department (ED) visit, intensive care unit (ICU) admission, and extra oxygen requirement outcomes, every odds ratio (OR) was <1 and p < 0.05. For rebound outcome, the OR was >1 and p > 0.05. For adverse events (AEs) outcome, the OR was >1 and p < 0.05. In conclusion, Paxlovid effectively reduced the risks of death, hospitalisation, death or hospitalisation, ED visit, ICU admission, and extra oxygen requirement. There was no significant statistical difference considering rebound, but people should pay attention to possible AEs. However, for rebound and AEs outcomes, observations in certain subgroups suggested conclusions contrary to the overall meta-analysis. Trial sequential analysis indicated these two outcomes have a risk of false negative or false positive conclusions, so additional original studies are needed for further validation.

Paxlovid reduces the 28-day mortality of patients with COVID-19: a retrospective cohort study.

PURPOSE: In this study, we aim to explore the efficacy of paxlovid on reducing mortality of COVID-19 patients in clinical setting, especially whether paxlovid modifies the risk of death in these severe and critical patients. METHODS: Our retrospective cohort study was conducted on the medical records of patients, consecutively admitted for COVID-19 to five hospitals in Chongqing, China from Dec 8, 2022 to Jan 20, 2023. Based on whether patients received paxlovid during their hospitalization, patients were grouped as paxlovid group and non-paxlovid group. We used 1:1 ratio propensity score matching (PSM) in our study to adjust for confounding factors and differences between groups. Statistical analysis were performed by SPSS 23.0. The differences in 28-day mortality between these two groups and its influencing factors were the main results we focused on. RESULTS: There were 1018 patients included in our study cohort. With 1:1 ratio PSM, each of the paxlovid group and non-paxlovid group included 237 patients. The results showed that patients using paxlovid have a lower 28-day mortality in overall population either before PSM (OR 0.594, 95% CI 0.385-0.917, p = 0.019) or after PSM (OR 0.458, 95% CI 0.272-0.774, p = 0.003) with multivariable adjusted logistic regression models. Meanwhile, in severe subgroup, it showed similar findings.With paxlovid treatment, it showed a significantly lower 28-day mortality in severe subgroup both before PSM (28% vs.41%, p = 0.008) and after PSM (19% vs.32%, p = 0.007). CONCLUSION: Paxlovid can significantly reduce the risk of 28-day mortality in overall population and severe subgroup patients.This study distinguished the severe subgroup patients with COVID-19 who benefit more from paxlovid treatment.

Azvudine versus paxlovid for oral treatment of COVID-19 in Chinese patients.

PURPOSE: To explore the effect of azvudine as compared to paxlovid for oral treatment of hospitalized patients with SARS-CoV-2 infection. METHODS: We analyzed data from a cohort of patients with SARS-CoV-2 infection in Shandong provincial hospital between February 15 and March 15, 2023. The primary outcome was time to sustained clinical recovery through Day 28 and secondary outcomes included the percentage of participants who died from any cause by Day 28, the average hospitilization time and expenses, the changes in liver and kidney function and adverse events. The Kaplan-Meier method and Cox regression model was used for statistical analysis. RESULTS: There was no significant difference between azvudine and paxlovid in terms of time to sustained clinical recovery (p = 0.429) and death rates (p = 0.687). As for hospitalization time and fee, no significant differences were observed between azvudine group and paxlovid group (Hospitalization time: p = 0.633; Hospitalization fee: p = 0.820). In addition, there were no significant differences in the effects of the two drugs on liver and kidney function (p > 0.05). CONCLUSION: Among adults who were hospitalised with SARS-CoV-2 infection, azvudine was noninferior to paxlovid in terms of time to sustained clinical recovery, death rates, hospitalization time and cost, with few safety concerns. TRIAL REGISTRATION: ChiCTR2300071309; Registered 11 May 2023. LEVEL OF EVIDENCE: Level III; Retrospective cohort study.

Nirmatrelvir/Ritonavir (Paxlovid) Use Among Individuals at Risk of Severe COVID-19: An Analysis of the National COVID Cohort Collaborative (N3C).

PURPOSE: Paxlovid is effective in reducing COVID-19 hospitalization and mortality. This study characterized Paxlovid use and evaluated racial/ethnic disparities over time among community-dwelling adults at high risk of progression to severe COVID-19 disease. METHODS: This retrospective cohort study used the National COVID Cohort Collaborative (N3C) data and included individuals aged 18 years or older diagnosed with COVID-19 between January 2022 and December 2023. The study cohort included nonhospitalized individuals who were at high risk of COVID-19 progression, and selected the first COVID-19 episode in each quarter, including reinfection episodes. Paxlovid use was defined as receiving Paxlovid within ±5 days of a COVID-19 diagnosis. We used descriptive statistics to characterize Paxlovid use overall and by calendar quarter and race/ethnicity. We used a generalized estimating equations (GEE) models to quantify the association of race/ethnicity with Paxlovid use controlling for age, gender, and clinical characteristics. RESULTS: Among 1 264 215 individuals at high risk of disease progression (1 404 607 episodes), Paxlovid use increased from 1.2% in January-March 2022 to 35.1% in October-December 2023. Paxlovid use was more common among non-Hispanic White individuals (23.9%) than non-Hispanic Black (16.5%) and Latinx/e (16.7%) patients. After adjusting age, gender, and clinical characteristics, Paxlovid use was less likely among non-Hispanic Black (odds ratio [OR] 0.69, 95% confidence interval [CI] 0.68-0.70) and Latinx/e (OR 0.72, CI 0.71-0.73) patients than non-Hispanic White patients. CONCLUSIONS: Among a large, diverse cohort of community-dwelling individuals with COVID-19, nearly two out of three eligible individuals did not receive Paxlovid, and minoritized racial/ethnic groups were less likely to use Paxlovid than their non-Hispanic White individuals.

Molnupiravir and Nirmatrelvir-Ritonavir: Oral Coronavirus Disease 2019 Antiviral Drugs.

At a crucial time with rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant globally, the United States Food and Drug Administration has issued an emergency use authorization for 2 oral antivirals, molnupiravir (in persons aged ≥18 years) and nirmatrelvir-ritonavir (Paxlovid) (in persons aged ≥12 years weighing ≥40 kg), for the outpatient treatment of patients with mild to moderate coronavirus disease 2019 (COVID-19) who are at risk for progression. Molnupiravir is a nucleoside analogue, whereas nirmatrelvir is a SARS-CoV-2 main protease inhibitor, and ritonavir is a human immunodeficiency virus type 1 protease inhibitor. Drug interactions are a major concern for nirmatrelvir-ritonavir. Nirmatrelvir-ritonavir demonstrated a greater risk reduction in hospitalization and death than molnupiravir compared to placebo. Both drugs need to be started within 5 days of symptoms onset and given for 5 days' duration. This article reviews the 2 oral COVID-19 antiviral drugs including the mechanisms of action, antiviral activity, pharmacokinetics, drug interactions, clinical experience including trials, adverse events, recommended indications, and formulary considerations.

Rebound Phenomenon After Nirmatrelvir/Ritonavir Treatment of Coronavirus Disease 2019 (COVID-19) in High-Risk Persons.

In a cohort of 483 high-risk patients treated with nirmatrelvir/ritonavir for COVID-19, 2 patients (0.4%) required hospitalization by day 30. Four patients (0.8%) experienced rebound of symptoms, which were generally mild, at a median of 9 days after treatment, and all resolved without additional COVID-19-directed therapy.

Oral Nirmatrelvir and Ritonavir for Coronavirus Disease 2019 in Vaccinated, Nonhospitalized Adults Aged 18-50 Years.

BACKGROUND: The effects of nirmatrelvir/ritonavir (NMV/r [Paxlovid]) on coronavirus disease 2019 (COVID-19) outcomes in younger vaccinated adults are unclear. The objective of this study was to assess if NMV/r use in vaccinated adults aged ≤50 years is associated with improved outcomes and to identify beneficial and nonbeneficial subgroups. METHODS: In this cohort study, we generated 2 propensity-matched cohorts of 2547 patients from an 86 119-person cohort assembled from the TriNetX database. Patients in 1 cohort received NMV/r, and patients in the matched control cohort did not. The main outcome was composite of all-cause emergency department visits, hospitalization, and mortality. RESULTS: The composite outcome was detected in 4.9% of the NMV/r cohort and 7.0% of the non-NMV/r cohort (odds ratio, 0.683 [95% confidence interval, .540-.864]; P = .001), indicating a 30% relative risk reduction. The number needed to treat (NNT) for the primary outcome was 47. Subgroup analyses found significant associations for patients with cancer (NNT = 45), cardiovascular disease (NNT = 30), and both conditions (NNT = 16). No benefit was found for patients with only chronic lower respiratory disorders (asthma/chronic obstructive pulmonary disease [COPD]) or without serious comorbidities. Thirty-two percent of NMV/r prescriptions in the overall database were for 18- to 50-year-olds. CONCLUSIONS: NMV/r use in vaccinated adults aged 18-50 years, especially with serious comorbidities, was associated with reduced all-cause hospital visits, hospitalization, and mortality in the first 30 days of COVID-19 illness. However, NMV/r in patients without significant comorbidities or with only asthma/COPD had no association of benefit. Therefore, identifying high-risk patients should be a priority and overprescription should be avoided.

Oral Nirmatrelvir and Ritonavir in Nonhospitalized Vaccinated Patients With Coronavirus Disease 2019.

BACKGROUND: Treatment of coronavirus disease 2019 (COVID-19) with nirmatrelvir plus ritonavir (NMV-r) in high-risk nonhospitalized unvaccinated patients reduced the risk of progression to severe disease. However, the potential benefits of NMV-r among vaccinated patients are unclear. METHODS: We conducted a comparative retrospective cohort study using the TriNetX research network. Patients ≥18 years of age who were vaccinated and subsequently developed COVID-19 between 1 December 2021 and 18 April 2022 were included. Cohorts were developed based on the use of NMV-r within 5 days of diagnosis. The primary composite outcome was all-cause emergency room (ER) visit, hospitalization, or death at a 30-day follow-up. Secondary outcomes included individual components of primary outcomes, multisystem symptoms, COVID-19-associated complications, and diagnostic test utilization. RESULTS: After propensity score matching, 1130 patients remained in each cohort. A primary composite outcome of all-cause ER visits, hospitalization, or death in 30 days occurred in 89 (7.87%) patients in the NMV-r cohort compared with 163 (14.4%) patients in the non-NMV-r cohort (odds ratio: .5; 95% confidence interval: .39-.67; P < .005) consistent with 45% relative risk reduction. A significant reduction in multisystem symptom burden and subsequent complications, such as lower respiratory tract infection, cardiac arrhythmia, and diagnostic radiology testing, were noted in NMV-r-treated patients. There was no apparent increase in serious complications between days 10 and 30. CONCLUSIONS: Treatment with NMV-r in nonhospitalized vaccinated patients with COVID-19 was associated with a reduced likelihood of ER visits, hospitalization, or death. Complications and overall resource utilization were also decreased.

Effectiveness of Paxlovid in Reducing Severe Coronavirus Disease 2019 and Mortality in High-Risk Patients.

BACKGROUND: Paxlovid was granted an Emergency Use Authorization for the treatment of mild to moderate coronavirus disease 2019 (COVID-19), based on the interim analysis of the Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients (EPIC-HR) trial. Paxlovid effectiveness needs to be assessed in a noncontrolled setting. In this study we used population-based real-world data to evaluate the effectiveness of Paxlovid. METHODS: The database of the largest healthcare provider in Israel was used to identify all adults aged 18 years or older with first-ever positive test for severe acute respiratory syndrome coronavirus 2 between January and February 2022, who were at high risk for severe COVID-19 and had no contraindications for Paxlovid use. Patients were included irrespective of their COVID-19 vaccination status. Cox hazard regression was used to estimate the 28-day hazard ratio (HR) for severe COVID-19 or mortality with Paxlovid examined as time-dependent variable. RESULTS: Overall, 180 351 eligible patients were included; of these, only 4737 (2.6%) were treated with Paxlovid, and 135 482 (75.1%) had adequate COVID-19 vaccination status. Both Paxlovid and adequate COVID-19 vaccination status were associated with significant decrease in the rate of severe COVID-19 or mortality with adjusted HRs of 0.54 (95% confidence interval [CI], .39-.75) and 0.20 (95% CI, .17-.22), respectively. Paxlovid appears to be more effective in older patients, immunosuppressed patients, and patients with underlying neurological or cardiovascular disease (interaction P < .05 for all). No significant interaction was detected between Paxlovid treatment and COVID-19 vaccination status. CONCLUSIONS: This study suggests that in the era of Omicron and in real-life settings, Paxlovid is highly effective in reducing the risk of severe COVID-19 or mortality.

Paxlovid mouth likely is mediated by activation of the TAS2R1 bitter receptor by nirmatrelvir.

Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has remained a public health threat since late 2019. Among the strategies rapidly developed to prevent and treat COVID-19, the antiviral medication Paxlovid (nirmatrelvir/ritonavir combination) has shown remarkable efficacy in reducing viral load and relieving clinical symptoms. Unexpectedly, a persistent bitter/bad taste, referred to as "Paxlovid mouth", has been frequently noted. Consistent with this, dysgeusia (altered taste) is listed as a main adverse effect of Paxlovid based on clinical trial data. Nirmatrelvir inhibits Mpro, a SARS-CoV-2 main protease, whereas ritonavir prolongs the activity of nirmatrelvir by slowing its metabolism. Prior usage of ritonavir in other conditions has not been linked to a persistent bad taste, despite the fact that ritonavir tastes bitter. Therefore, we hypothesized that nirmatrelvir may account for Paxlovid mouth by activating one or more of the 25 human TAS2R bitter taste receptors. Here, we show that TAS2R1 is the primary bitter receptor activated by nirmatrelvir, at concentrations as low as 15 µM, which overlaps with plasma concentrations of nirmatrelvir in a subset of patients. We also show that saccharin, a non-nutritive sweetener that may block the activity of TAS2R1, has little or no effect on nirmatrelvir-stimulated TAS2R1 activity. Such findings may help identify novel strategies to alleviate Paxlovid mouth and increase treatment compliance.