Effectiveness of nirmatrelvir-ritonavir in preventing hospital admissions and deaths in people with COVID-19: a cohort study in a large US health-care system

Cost-effectiveness of nirmatrelvir/ritonavir for high-risk adult outpatients with COVID-19 in Japan

INTRODUCTION

This study aimed to evaluate the cost-effectiveness of nirmatrelvir/ritonavir (Nir/Rit) for adult outpatients with COVID-19 from the perspective of a Japanese public healthcare payer.

METHODS

A cost-effectiveness simulation was conducted comparing Nir/Rit for the outpatient treatment of high-risk COVID-19 patients to best supportive care (BSC) without antiviral or antibody drugs. The analytical model was divided into two phases: the treatment phase, lasting 35 days from the start of COVID-19 treatment, and the post-treatment phase. Patients who survived the treatment phase were assumed to follow a general population survival curve. Expected costs and expected quality-adjusted life years (QALYs) for both BSC and Nir/Rit were calculated for ages 40 to 80 to obtain the incremental cost-effectiveness ratio (ICER). The robustness of the results was evaluated through deterministic and probabilistic sensitivity analysis (PSA).

RESULTS

The ICERs for patients aged 40, 50, 60, 70, and 80 were 18,854,276 Japanese Yen (JPY)/QALY, 8,482,034 JPY/QALY, 4,976,612 JPY/QALY, 2,636,096 JPY/QALY, and 1,597,783 JPY/QALY, respectively. In the deterministic sensitivity analysis, both the mortality risk during the treatment phase and the relative mortality risk with Nir/Rit had a high impact on ICER across all ages. In the PSA, when the willingness-to-pay (WTP) threshold was set at 5 million JPY/QALY, the probability of the ICER being below the WTP threshold was 0%, 0.2%, 45.4%, 99.9%, and 100% at ages 40, 50, 60, 70, and 80, respectively.

CONCLUSION

Nir/Rit is cost-effective for older individuals aged 60 and over but not for younger age groups.

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.

Assessing the benefit-risk balance of drugs. Some lessons from the COVID pandemic

INTRODUCTION

Drug efficacy and effectiveness are assessed respectively through clinical trials and pharmaco-epidemiological studies. However, relative and absolute benefits of drugs are distinct measures that must be considered in relation to the baseline risk of disease incidence, complication or progression. On the other hand, adverse drug reactions are independent of the basic risk but depend on the characteristics of the population treated. Given these prerequisites, how can we balance the benefits and risks of drugs?

AREAS COVERED

We use the example of therapeutics evaluated during Covid to describe how assessing the benefit-risk balance of drugs is a complex process.

EXPERT OPINION

Clinical trials are not designed to identify rare adverse events, underscoring the necessity for a pharmacovigilance system. Evaluating the balance between the benefits and risks of drugs is an ongoing process, demanding the simultaneous analysis of data from clinical trials, potential drug-drug interactions, pharmacovigilance monitoring and pharmaco-epidemiological studies, to identify potential safety concerns. In addition, pharmacologists must play a major role in educating the general public about drugs, aiding in the accurate interpretation of the benefit-risk balance and preventing misinformation.

Effectiveness of nirmatrelvir/ritonavir in children and adolescents aged 12-17 years following SARS-CoV-2 Omicron infection: A target trial emulation

Currently there is a lack of randomized trial data examining the use of the antiviral nirmatrelvir/ritonavir in paediatric patients with SARS-CoV-2 infection. This target trial emulation study aims to address this gap by evaluating the use of nirmatrelvir/ritonavir in non-hospitalized paediatric patients aged 12-17 years with SARS-CoV-2 Omicron variant infection. Among paediatric patients diagnosed between 16th March 2022 and 5th February 2023, exposure was defined as outpatient nirmatrelvir/ritonavir treatment within 5 days of symptom onset or COVID-19 diagnosis. Primary outcome was 28 day all-cause mortality or all-cause hospitalization, while secondary outcomes were 28 day in-hospital disease progression, 28 day COVID-19-specific hospitalization, multisystem inflammatory syndrome in children (MIS-C), acute liver injury, acute renal failure, and acute respiratory distress syndrome. Overall, 49,378 eligible paediatric patients were included. Nirmatrelvir/ritonavir treatment was associated with reduced 28 day all-cause hospitalization (absolute risk reduction = 0.23%, 95%CI = 0.19%-0.31%; relative risk = 0.66, 95%CI = 0.56-0.71). No events of mortality, in-hospital disease progression, or adverse clinical outcomes were observed among nirmatrelvir/ritonavir users. The findings confirmed the effectiveness of nirmatrelvir/ritonavir in reducing all-cause hospitalization risk among non-hospitalized pediatric patients with SARS-CoV-2 Omicron variant infection.

Clinical Outcome and 7-Day Virological Clearance in High-Risk Patients with Mild-Moderate COVID-19 Treated with Molnupiravir, Nirmatrelvir/Ritonavir, or Remdesivir

INTRODUCTION

We compared the effectiveness and virological clearance (VC) at day 7 (T7) post-treatment with molnupiravir, nirmatrelvir/ritonavir, and remdesivir in SARS-CoV-2-infected patients at high risk (HR) for clinical progression.

METHODS

We conducted a retrospective study enrolling HR patients with mild-to-moderate COVID-19 (Jan-Oct 2022) treated with nirmatrelvir/ritonavir or molnupiravir or 3 days of remdesivir. We investigated clinical recovery at T7 (resolution of symptoms for ≥ 72 h or all-cause death), VC at T7 (PCR/antigenic negative nasopharyngeal swab), and median time to VC (days from symptom onset to the first negative swab). Factors associated with VC were investigated by logistic regression.

RESULTS

In the study, 92/376 (43.8%) patients received molnupiravir, 150/376 (24.7%) nirmatrelvir/ritonavir, and 134/376 (31.5%) remdesivir. Forty-nine (13%) patients were unvaccinated or incompletely vaccinated. Patients treated with nirmatrelvir/ritonavir were younger and presented immunodeficiencies more frequently; remdesivir was used more commonly in patients hospitalized for other diseases. A high proportion of patients obtained clinical recovery without differences among the therapies (97.5% for molnupiravir, 98.3% for nirmatrelvir/ritonavir, and 93.6% for remdesivir); 12 (3.7%) patients died. Nirmatrelvir/ritonavir was associated with a higher proportion of T7 VC and a shorter time to VC compared to molnupiravir/remdesivir, also after adjustment for age and immunodeficiency (AOR 0.445 RDV vs. NMV-r, 95% CI 0.240-0.826, p = 0.010; AOR 0.222 MNP vs. NMV-r, 95% CI 0.105-0.472, p < 0.001).

CONCLUSIONS

SARS-COV-2 antiviral treatments are an excellent therapeutic strategy in HR patients. Nirmatrelvir/ritonavir showed a higher proportion of VC as early as 7 days after treatment, confirming its likely superiority in indirect comparisons.

Joint analysis of vaccination effectiveness and antiviral drug effectiveness for COVID-19: a causal inference approach

OBJECTIVES

This study aims to estimate the causal effects of oral antivirals and vaccinations in the prevention of all-cause mortality and progression to severe COVID-19 in an integrative setting with both antivirals and vaccinations considered as interventions.

METHODS

We identified hospitalized adult patients (i.e. aged 18 or above) in Hong Kong with confirmed SARS-CoV-2 infection between March 16, 2022, and December 31, 2022. An inverse probability-weighted (IPW) Andersen-Gill model with time-dependent predictors was used to address immortal time bias and produce causal estimates for the protection effects of oral antivirals and vaccinations against severe COVID-19.

RESULTS

Given prescription is made within 5 days of confirmed infection, nirmatrelvir-ritonavir is more effective in providing protection against all-cause mortality and development into severe COVID-19 than molnupiravir. There was no significant difference between CoronaVac and Comirnaty in the effectiveness of reducing all-cause mortality and progression to severe COVID-19.

CONCLUSIONS

The use of oral antivirals and vaccinations causes lower risks of all-cause mortality and progression to severe COVID-19 for hospitalized SARS-CoV-2 patients.

Effectiveness of nirmatrelvir/ritonavir and molnupiravir in non-hospitalized adults with COVID-19: systematic review and meta-analysis of observational studies

OBJECTIVE

To determine the effectiveness of nirmatrelvir/ritonavir and molnupiravir among vaccinated and unvaccinated non-hospitalized adults with COVID-19.

METHODS

Observational studies of nirmatrelvir/ritonavir or molnupiravir compared to no antiviral drug treatment for COVID-19 in non-hospitalized adults with data on vaccination status were included. We searched MEDLINE, EMBASE, Scopus, Web of Science, WHO COVID-19 Research Database and medRxiv for reports published between 1 January 2022 and 8 November 2023. The primary outcome was a composite of hospitalization or mortality up to 35 days after COVID-19 diagnosis. Risk of bias was assessed with ROBINS-I. Risk ratios (RR), hazard ratios (HR) and risk differences (RD) were separately estimated using random-effects models.

RESULTS

We included 30 cohort studies on adults treated with nirmatrelvir/ritonavir (n = 462 279) and molnupiravir (n = 48 008). Nirmatrelvir/ritonavir probably reduced the composite outcome (RR 0.62, 95%CI 0.55-0.70; I2 = 0%; moderate certainty) with no evidence of effect modification by vaccination status (RR Psubgroup = 0.47). In five studies, RD estimates against the composite outcome for nirmatrelvir/ritonavir were 1.21% (95%CI 0.57% to 1.84%) in vaccinated and 1.72% (95%CI 0.59% to 2.85%) in unvaccinated subgroups.Molnupiravir may slightly reduce the composite outcome (RR 0.75, 95%CI 0.67-0.85; I2 = 32%; low certainty). Evidence of effect modification by vaccination status was inconsistent among studies reporting different effect measures (RR Psubgroup = 0.78; HR Psubgroup = 0.08). In two studies, RD against the composite outcome for molnupiravir were -0.01% (95%CI -1.13% to 1.10%) in vaccinated and 1.73% (95%CI -2.08% to 5.53%) in unvaccinated subgroups.

CONCLUSIONS

Among cohort studies of non-hospitalized adults with COVID-19, nirmatrelvir/ritonavir is effective against the composite outcome of severe COVID-19 independent of vaccination status. Further research and a reassessment of molnupiravir use among vaccinated adults are warranted.

REGISTRATION

PROSPERO CRD42023429232.

Effectiveness of Nirmatrelvir-Ritonavir for the Prevention of COVID-19-Related Hospitalization and Mortality: A Systematic Literature Review

BACKGROUND

Nirmatrelvir/ritonavir (NMV/r) is an oral antiviral drug used to treat mild-to-moderate coronavirus disease 2019 (COVID-19) in patients aged 12 years or older at high risk of progression to severe disease (eg, hospitalization and death). Despite being the preferred option for outpatient treatment in the majority of countries worldwide, NMV/r is currently underutilized in real-world clinical practice.

AREAS OF UNCERTAINTY

As numerous real-world studies have described patient outcomes following treatment with NMV/r, this systematic literature review provides a comprehensive summary of evidence on NMV/r effectiveness against hospitalization and mortality further organized by clinically meaningful categories, such as acute versus longer-term follow-up, age, underlying health conditions, and vaccination status, to help inform health care decision making.

DATA SOURCES

We searched Embase and PubMed (December 22, 2021-March 31, 2023) and congress abstracts (December 1, 2021-December 31, 2022) for reports describing NMV/r effectiveness.

THERAPEUTIC ADVANCES

In total, 18 real-world studies met final selection criteria. The evidence showed that NMV/r significantly reduced postinfection risk of all-cause and COVID-19-related hospitalization and mortality in both acute (≤30 days) (21%-92%) and longer-term (>30 days) (1%-61%) follow-up. The reduction in postinfection risk was higher when treatment was received within 5 days of symptom onset. Real-world effectiveness of NMV/r treatment was observed regardless of age, underlying high-risk conditions, and vaccination status.

CONCLUSION

The systematic literature review findings demonstrated the effectiveness of NMV/r against hospitalization and mortality during the Omicron period among individuals at high risk of progression to severe COVID-19 disease.

Nirmatrelvir Resistance in an Immunocompromised Patient with Persistent Coronavirus Disease 2019

Although the coronavirus disease 2019 (COVID-19) pandemic is coming to an end, it still poses a threat to the immunocompromised and others with underlying diseases. Especially in cases of persistent COVID-19, new mutations conferring resistance to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) therapies have considerable clinical implications. We present a patient who independently acquired a T21I mutation in the 3CL protease after nirmatrelvir exposure. The T21I mutation in the 3CL protease is one of the most frequent mutations responsible for nirmatrelvir resistance. However, limited reports exist on actual cases of SARS-CoV-2 with T21I and other mutations in the 3CL protease. The patient, a 55 year-old male, had COVID-19 during chemotherapy for multiple myeloma. He was treated with nirmatrelvir early in the course of the disease but relapsed, and SARS-CoV-2 with a T21I mutation in the 3CL protease was detected in nasopharyngeal swab fluid. The patient had temporary respiratory failure but later recovered well. During treatment with remdesivir and dexamethasone, viruses with the T21I mutation in the 3CL protease showed a decreasing trend during disease progression while increasing during improvement. The impact of drug-resistant SARS-CoV-2 on the clinical course, including its severity, remains unknown. Our study is important for examining the clinical impact of nirmatrelvir resistance in COVID-19.

Real-world application of nirmatrelvir/ritonavir in hospitalized COVID-19 patients with onset of symptoms beyond 5 days: a comparative study

PURPOSE

Physicians may administer Nirmatrelvir-ritonavir to patients who have been symptomatic for more than 5 days. There is currently no clear evidence to support this approach.

METHODS

A real-world study was conducted to investigate the potential relationship between the administration of Nirmatrelvir-ritonavir and the rates of intubation or in-hospital mortality among COVID-19 patients who experienced symptoms for more than 5 days. The end point was a composite event of intubation or in-hospital mortality. The outcomes between those patients who received Nirmatrelvir-ritonavir and those who did not were compared.

RESULTS

A total of 847 patients were included in the analysis. Among them, 312 patients (36.84%) received Nirmatrelvir-ritonavir. Within the entire population, 86 patients (10.15%) experienced intubation or in-hospital mortality. The main analysis indicated that there was a significant association between the application of Nirmatrelvir-ritonavir and intubation or in-hospital mortality, with an odds ratio of 0.50 (95% confidence interval, 0.28 to 0.87; P = 0.0153) using inverse probability of treatment weighting. The finding was consistent with multiple sensitivity analyses.

CONCLUSIONS

The application of Nirmatrelvir-ritonavir was associated with a significantly reduced risk of intubation or death in hospitalized COVID-19 patients who experienced symptoms for more than 5 days as compared to those who did not receive the treatment.

Coordination chemistry suggests that independently observed benefits of metformin and Zn2+ against COVID-19 are not independent

Independent trials indicate that either oral Zn2+ or metformin can separately improve COVID-19 outcomes by approximately 40%. Coordination chemistry predicts a mechanistic relationship and therapeutic synergy. Zn2+ deficit is a known risk factor for both COVID-19 and non-infectious inflammation. Most dietary Zn2+ is not absorbed. Metformin is a naked ligand that presumably increases intestinal Zn2+ bioavailability and active absorption by cation transporters known to transport metformin. Intracellular Zn2+ provides a natural buffer of many protease reactions; the variable "set point" is determined by Zn2+ regulation or availability. A Zn2+-interactive protease network is suggested here. The two viral cysteine proteases are therapeutic targets against COVID-19. Viral and many host proteases are submaximally inhibited by exchangeable cell Zn2+. Inhibition of cysteine proteases can improve COVID-19 outcomes and non-infectious inflammation. Metformin reportedly enhances the natural moderating effect of Zn2+ on bioassayed proteome degradation. Firstly, the dissociable metformin-Zn2+ complex could be actively transported by intestinal cation transporters; thereby creating artificial pathways of absorption and increased body Zn2+ content. Secondly, metformin Zn2+ coordination can create a non-natural protease inhibitor independent of cell Zn2+ content. Moderation of peptidolytic reactions by either or both mechanisms could slow (a) viral multiplication (b) viral invasion and (c) the pathogenic host inflammatory response. These combined actions could allow development of acquired immunity to clear the infection before life-threatening inflammation. Nirmatrelvir (Paxlovid®) opposes COVID-19 by selective inhibition the viral main protease by a Zn2+-independent mechanism. Pending safety evaluation, predictable synergistic benefits of metformin and Zn2+, and perhaps metformin/Zn2+/Paxlovid® co-administration should be investigated.

COVID-19 hospitalization risk after outpatient nirmatrelvir/ritonavir use, January to August 2022, North Carolina

BACKGROUND

In the USA, nirmatrelvir/ritonavir is authorized for the treatment of mild-to-moderate COVID-19 in patients at least 12 years of age, at high risk for progression to severe COVID-19.

OBJECTIVES

To estimate the impact of outpatient nirmatrelvir/ritonavir on COVID-19 hospitalization risk in a US healthcare system.

METHODS

We conducted a cohort study using electronic health records among outpatients with a positive SARS-CoV-2 PCR test between January and August 2022. We evaluated the association of nirmatrelvir/ritonavir therapy with time to hospitalization by estimating adjusted HRs and assessed the impact of nirmatrelvir/ritonavir on predicted COVID-19 hospitalizations using machine-learning methods.

RESULTS

Among 44 671 patients, 4948 (11%) received nirmatrelvir/ritonavir, and 201 (0.4%) were hospitalized within 28 days of COVID-19 diagnosis. Nirmatrelvir/ritonavir recipients were more likely to be older, white, vaccinated, have comorbidities and reside in areas with higher average socioeconomic status. The 28 day cumulative incidence of hospitalization was 0.06% (95% CI: 0.02%-0.17%) among nirmatrelvir/ritonavir recipients and 0.52% (95% CI: 0.46%-0.60%) among non-recipients. For nirmatrelvir/ritonavir versus no therapy, the age-adjusted HR was 0.08 (95% CI: 0.03-0.26); the fully adjusted HR was 0.16 (95% CI: 0.05-0.50). In the machine-learning model, the primary features reducing predicted hospitalization risk were nirmatrelvir/ritonavir, younger age, vaccination, female gender and residence in a higher socioeconomic status area.

CONCLUSIONS

COVID-19 hospitalization risk was reduced by 84% among nirmatrelvir/ritonavir recipients in a large, diverse healthcare system during the Omicron wave. These results suggest that nirmatrelvir/ritonavir remained highly effective in a setting substantially different than the original clinical trials.

Nirmatrelvir and ritonavir combination against COVID-19 caused by omicron BA.2.2 in the elderly: A single-center large observational study

BACKGROUND

Since coronavirus 2019 (COVID-19) swept the world, a variety of novel therapeutic and prevention strategies have been developed, among which nirmatrelvir-ritonavir is highly recommended. We intended to assess the effectiveness and safety of nirmatrelvir-ritonavir in the elderly mild-to-moderate COVID-19 population caused by the omicron BA.2.2 variant in real-world settings.

METHODS

An observational study was conducted retrospectively to review the outcomes of mild-to-moderate COVID-19 patients admitted between April 26 and June 30, 2022. Patients' baseline characteristics were collected and assessed. Participants in the intervention group were administered nirmatrelvir-ritonavir in addition to standard care, whereas those in the control group only received standard care. The primary outcome was the duration between the initial positive reverse-transcription polymerase chain reaction (RT-PCR) test and the subsequent conversion to a negative result.

RESULTS

The analysis included 324 patients who were administered nirmatrelvir-ritonavir and an equal number of control patients. The patient characteristics in both groups were evenly matched. The average duration from the initial positive RT-PCR to negative conversion was similar in both groups (16.2 ± 5.0 vs. 16.1 ± 6.3 days, p = .83). Control patients exhibited slower conversion in comparison to patients who received nirmatrelvir-ritonavir treatment within 10 days of symptom onset.

CONCLUSIONS

These findings suggest that administering nirmatrelvir-ritonavir within 10 days of symptom onset could potentially reduce the time it takes for SARS-CoV-2-infected patients to negative RT-PCR results, thereby expanding the current usage guidelines for nirmatrelvir-ritonavir.

Predictors of nirmatrelvir-ritonavir receipt among COVID-19 patients in a large US health system

A clear understanding of real-world uptake of nirmatrelvir-ritonavir for treatment of SARS-CoV-2 can inform treatment allocation strategies and improve interpretation of effectiveness studies. We used data from a large US healthcare system to describe nirmatrelvir-ritonavir dispenses among all SARS-CoV-2 positive patients aged ≥ 12 years meeting recommended National Institutes of Health treatment eligibility criteria for the study period between 1 January and 31 December, 2022. Overall, 10.9% (N = 34,791/319,900) of treatment eligible patients with SARS-CoV-2 infections received nirmatrelvir-ritonavir over the study period. Although uptake of nirmatrelvir-ritonavir increased over time, by the end of 2022, less than a quarter of treatment eligible patients with SARS-CoV-2 infections had received nirmatrelvir-ritonavir. Across patient demographics, treatment was generally consistent with tiered treatment guidelines, with dispenses concentrated among patients aged ≥ 65 years (14,706/63,921; 23.0%), and with multiple comorbidities (10,989/54,431; 20.1%). However, neighborhoods of lower socioeconomic status (upper third of neighborhood deprivation index [NDI]) had between 12% (95% CI: 7-18%) and 28% (25-32%) lower odds of treatment dispense over the time periods studied compared to the lower third of NDI distribution, even after accounting for demographic and clinical characteristics. A limited chart review (N = 40) confirmed that in some cases a decision not to treat was appropriate and aligned with national guidelines to use clinical judgement on a case-by-case basis. There is a need to enhance patient and provider awareness on the availability and benefits of nirmatrelvir-ritonavir for the treatment of COVID-19 illness.

Real-world use of nirmatrelvir-ritonavir in COVID-19 outpatients during BQ.1, BQ.1.1., and XBB.1.5 predominant omicron variants in three U.S. health systems: a retrospective cohort study

Background

Ritonavir-boosted Nirmatrelvir (NMV-r), a protease inhibitor with in vitro activity against SARS-CoV-2, can reduce risk of progression to severe COVID-19 among high-risk individuals infected with earlier variants, but less is known about its effectiveness against omicron variants BQ.1/BQ.1.1/XBB.1.5. We sought to evaluate effectiveness of NMV-r in BQ.1/BQ.1.1/XBB.1.5 omicron variants by comparing hospitalisation rates to NMV-r treated patients during a previous omicron phase and to contemporaneous untreated patients.

Methods

We conducted a retrospective observational cohort study of non-hospitalised adult patients with SARS-CoV-2 infection using real-world data from three health systems in Colorado and Utah, and compared hospitalisation rates in NMV-r-treated patients in a BA.2/BA.2.12.1/BA.4/BA.5 variant-predominant (first) phase (April 3, 2022-November 12, 2022), with a BQ.1/BQ.1.1/XBB.1.5 variant-predominant (second) phase (November 13, 2022-March 7, 2023). In the primary analysis, we used Firth logistic regression with a two-segment (phase) linear time model, and pre-specified non-inferiority bounds for the mean change between segments. In a pre-specified secondary analysis, we inferred NMV-r effectiveness in a cohort of treated and untreated patients infected during the second phase. For both analyses, the primary outcome was 28-day all-cause hospitalisation. Subgroup analyses assessed treatment effect heterogeneity.

Findings

In the primary analysis, 28-day all-cause hospitalisation rates in NMV-r treated patients in the second phase (n = 12,061) were non-inferior compared to the first phase (n = 25,075) (198 [1.6%] vs. 345 [1.4%], adjusted odds ratio (aOR): 0.76 [95% CI 0.54-1.06]), with consistent results among secondary endpoints and key subgroups. Secondary cohort analyses revealed additional evidence for NMV-r effectiveness, with reduced 28-day hospitalisation rates among treated patients compared to untreated patients during a BQ.1/BQ.1.1/XBB.1.5 predominant phase (198/12,061 [1.6%] vs. 376/10,031 [3.7%], aOR 0.34 [95% CI 0.30-0.38), findings robust to additional sensitivity analyses.

Interpretation

Real-world evidence from major US healthcare systems suggests ongoing NMV-r effectiveness in preventing hospitalisation during a BQ.1/BQ.1.1/XBB.1.5-predominant phase in the U.S, supporting its continued use in similar patient populations.

Funding

U.S. National Institutes of Health.

Targeting Viral and Cellular Cysteine Proteases for Treatment of New Variants of SARS-CoV-2

The continuous emergence of SARS-CoV-2 variants caused the persistence of the COVID-19 epidemic and challenged the effectiveness of the existing vaccines. The viral proteases are the most attractive targets for developing antiviral drugs. In this scenario, our study explores the use of HIV-1 protease inhibitors against SARS-CoV-2. An in silico screening of a library of HIV-1 proteases identified four anti-HIV compounds able to interact with the 3CLpro of SARS-CoV-2. Thus, in vitro studies were designed to evaluate their potential antiviral effectiveness against SARS-CoV-2. We employed pseudovirus technology to simulate, in a highly safe manner, the adsorption of the alpha (α-SARS-CoV-2) and omicron (ο-SARS-CoV-2) variants of SARS-CoV-2 and study the inhibitory mechanism of the selected compounds for cell-virus interaction. The results reported a mild activity against the viral proteases 3CLpro and PLpro, but efficient inhibitory effects on the internalization of both variants mediated by cathepsin B/L. Our findings provide insights into the feasibility of using drugs exhibiting antiviral effects for other viruses against the viral and host SARS-CoV-2 proteases required for entry.

Characteristics and Outcomes of US Veterans With Immunocompromised Conditions at High Risk of SARS-CoV-2 Infection With or Without Receipt of Oral Antiviral Agents

OBJECTIVES

Molnupiravir and nirmatrelvir-ritonavir were the first oral antiviral agents to demonstrate reduced hospitalization or death in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but patients with immunocompromised conditions were not well-represented. The objective of this study was to characterize and compare the clinical outcomes of US veterans with immunocompromised conditions prescribed oral antivirals with those who did not receive oral antivirals for mild-to-moderate SARS-CoV-2 active infection.

METHODS

This was a retrospective, observational, nationwide propensity-matched analysis of US veterans with immunocompromised conditions who developed documented SARS-CoV-2 infection. The primary outcome was the composite of any hospitalization or death within 30 days of diagnosis. Secondary outcomes included 30-day comparative rates of (1) any hospitalization, (2) death, (3) intensive care requirement, and (4) subset analyses of outcomes by oral antiviral used and vaccination status.

RESULTS

The composite primary outcome was significantly lower in patients receiving oral antiviral therapy compared with those who did not (23/390 [5.9%] vs 57/390 [14.6%]; odds ratio, 0.37; 95% confidence interval, .22-.61). This difference was driven largely by fewer deaths in the oral antiviral group (1/390 [0.3%] vs 19/390 [4.9%]; odds ratio, 0.05; 95% confidence interval, .007-.38). There was no significant difference in rate of intensive care requirement. The composite outcome was improved in vaccinated patients (completing the first series or first booster dose) who received oral antiviral agents compared with those who did not receive oral antiviral agents. Compared with those prescribed nirmatrelvir-ritonavir, patients given molnupiravir were older, had a higher incidence of cautions/contraindications, greater prevalence of tobacco use, and more cardiovascular complications.

CONCLUSIONS

Use of molnupiravir or nirmatrelvir-ritonavir was associated with lower incidences of hospitalization or death within 30 days of diagnosis in US veterans with immunocompromised conditions, regardless of vaccination status. These findings support the use of either oral antiviral in this patient population.

Oral COVID-19 Antiviral Uptake Among a Highly Vaccinated US Cohort of Adults With SARS-CoV-2 Infection Between December 2021 and October 2022

Background

We described the oral nirmatrelvir/ritonavir (NMV/r) and molnupiravir (MOV) uptake among a subgroup of highly vaccinated adults in a US national prospective cohort who were infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between 12/2021 and 10/2022.

Methods

We estimate antiviral uptake within 5 days of SARS-CoV-2 infection, as well as age- and gender-adjusted antiviral uptake prevalence ratios by antiviral eligibility (based on age and comorbidities), sociodemographic characteristics, and clinical characteristics including vaccination status and history of long coronavirus disease 2019 (COVID).

Results

NMV/r uptake was 13.6% (95% CI, 11.9%-15.2%) among 1594 participants, and MOV uptake was 1.4% (95% CI, 0.8%-2.1%) among 1398 participants. NMV/r uptake increased over time (1.9%; 95% CI, 1.0%-2.9%; between 12/2021 and 3/2022; 16.5%; 95% CI, 13.0%-20.0%; between 4/2022 and 7/2022; and 25.3%; 95% CI, 21.6%-29.0%; between 8/2022 and 10/2022). Participants age ≥65 and those who had comorbidities for severe COVID-19 had higher NMV/r uptake. There was lower NMV/r uptake among non-Hispanic Black participants (7.2%; 95% CI, 2.4%-12.0%; relative to other racial/ethnic groups) and among individuals in the lowest income groups (10.6%; 95% CI, 7.3%-13.8%; relative to higher income groups). Among a subset of 278 participants with SARS-CoV-2 infection after 12/2021 who also had a history of prior SARS-CoV-2 infection, those with (vs without) a history of long COVID reported greater NMV/r uptake (22.0% vs 7.9%; P = .001). Among those prescribed NMV/r (n = 216), 137 (63%; 95% CI, 57%-70%) reported that NMV/r was helpful for reducing COVID-19 symptoms.

Conclusions

Despite proven effectiveness against severe outcomes, COVID-19 antiviral uptake remains low among those with SARS-CoV-2 infection in the United States. Further outreach to providers and patients to improve awareness of COVID-19 oral antivirals and indications is needed.

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.

Cost-Effectiveness of Oral Nirmatrelvir/Ritonavir in Patients at High Risk for Progression to Severe COVID-19 in the United States

OBJECTIVES

Nirmatrelvir/ritonavir (NMV/r) is an orally administered antiviral indicated for the outpatient treatment of patients with mild-to-moderate COVID-19 at high risk for disease progression to severe illness. We estimated the cost-effectiveness of NMV/r versus best supportive care for patients with mild-to-moderate COVID-19 at high risk for progression to severe illness from a US health sector perspective.

METHODS

A cost-effectiveness model was developed using a short-term decision-tree (1 year) followed by a lifetime 2-state Markov model (alive and dead). The short-term decision-tree captured costs and outcomes associated with the primary infection and healthcare utilization; survivors of the short-term decision-tree were followed until death assuming US quality-adjusted life years (QALYs), adjusted in the short-term for survivors of mechanical ventilation. Baseline rate of hospitalization and NMV/r effectiveness were taken from an Omicron-era US real-world study. Remaining inputs were informed by previous COVID-19 studies and publicly available US sources. Sensitivity analyses were conducted for all model inputs to test the robustness of model results.

RESULTS

NMV/r was found to decrease COVID-19 related hospitalizations (-0.027 per infected case) increase QALYs (+0.030), decrease hospitalization costs (-$1110), and increase total treatment cost (+$271), resulting in an incremental cost-effectiveness ratio of $8931/QALY. Results were most sensitive to baseline risk of hospitalization and NMV/r treatment effectiveness parameters. The probabilistic analysis indicated that NMV/r has a >99% probability of being cost-effective at a $100 000 willingness-to-pay threshold.

CONCLUSIONS

NMV/r is cost-effective vs best supportive care for patients at high risk for severe COVID-19 from a US health sector perspective.

Efficacy and safety of azvudine in symptomatic adult COVID-19 participants who are at increased risk of progressing to critical illness: a study protocol for a multicentre randomized double-blind placebo-controlled phase III trial

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 will coexist with humans for a long time, and it is therefore important to develop effective treatments for coronavirus disease 2019 (COVID-19). Recent studies have demonstrated that antiviral therapy is a key factor in preventing patients from progressing to severe disease, even death. Effective and affordable antiviral medications are essential for disease treatment and are urgently needed. Azvudine, a nucleoside analogue, is a potential low-cost candidate with few drug interactions. However, validation of high-quality clinical studies is still limited.

METHODS

This is a multicentre, randomized, double-blind, placebo-controlled phase III clinical trial involving 1096 adult patients with mild-to-moderate symptoms of COVID-19 who are at high risk for progression to severe COVID-19. Patients will be randomized to (1) receive azvudine tablets 5 mg daily for a maximum of 7 days or (2) receive placebo five tablets daily. All participants will be permitted to use a standard treatment strategy except antiviral therapy beyond the investigational medications. The primary outcome will be the ratio of COVID-19-related critical illness and all-cause mortality among the two groups within 28 days.

DISCUSSION

The purpose of this clinical trial is to determine whether azvudine can prevent patients at risk of severe disease from progressing to critical illness and death, and the results will identify whether azvudine is an effective and affordable antiviral treatment option for COVID-19.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05689034. Registered on 18 January 2023.

Effectiveness of Vaccines and Antiviral Drugs in Preventing Severe and Fatal COVID-19, Hong Kong

We compared the effectiveness and interactions of molnupiravir and nirmatrelvir/ritonavir and 2 vaccines, CoronaVac and Comirnaty, in a large population of inpatients with COVID-19 in Hong Kong. Both the oral antiviral drugs and vaccines were associated with lower risks for all-cause mortality and progression to serious/critical/fatal conditions (study outcomes). No significant interaction effects were observed between the antiviral drugs and vaccinations; their joint effects were additive. If antiviral drugs were prescribed within 5 days of confirmed COVID-19 diagnosis, usage was associated with lower risks for the target outcomes for patients >60, but not <60, years of age; no significant clinical benefit was found if prescribed beyond 5 days. Among patients >80 years of age, 3-4 doses of Comirnaty vaccine were associated with significantly lower risks for target outcomes. Policies should encourage COVID-19 vaccination, and oral antivirals should be made accessible to infected persons within 5 days of confirmed diagnosis.

Economic burden of COVID-19 for employers and employees in the United States

OBJECTIVE

Describe the economic burden of COVID-19 on employers and employees in the United States (US).

METHODS

A targeted literature review was conducted to evaluate the impact of COVID-19 on US-based employers and employees in terms of healthcare resource utilization (HCRU), medical costs, and costs associated with work-loss. Searches were conducted in MEDLINE, Embase, and EconLit using a combination of disease terms, populations, and outcomes to identify articles published from January 2021 to November 4, 2022. As data from the employer perspective were lacking, additional literature related to influenza were included to contextualize the impact of COVID-19, as it shifts into an endemic state, within the existing respiratory illness landscape.

RESULTS

A total of 41 articles were included in the literature review. Employer and employee perspectives were not well represented in the literature, and very few articles overlapped on any given outcome. HCRU, costs, and work impairment vary by community transmission levels, industry type, population demographics, telework ability, mitigation implementation measures, and company policies. Work-loss among COVID-19 cases were higher among the unvaccinated and in the week following diagnosis and for some, these continued for 6 months. HCRU is increased in those with COVID-19 and COVID-19-related HCRU can also continue for 6 months.

CONCLUSIONS

COVID-19 continues to be a considerable burden to employers. The majority of COVID-19 cases impact working age adults. HCRU is mainly driven by outpatient visits, while direct costs are driven by hospitalization. Productivity loss is higher for unvaccinated individuals. An increased focus to support mitigation measures may minimize hospitalizations and work-loss. A data-driven approach to implementation of workplace policies, targeted communications, and access to timely and appropriate therapies for prevention and treatment may reduce health-related work-loss and associated cost burden.

Optimal timing of nirmatrelvir/ritonavir treatment after COVID-19 symptom onset or diagnosis: target trial emulation

Reports of symptomatic rebound and/or test re-positivity among COVID-19 patients following the standard five-day treatment course of nirmatrelvir/ritonavir have sparked debates regarding optimal treatment timing and dosage. It is unclear whether initiating nirmatrelvir/ritonavir immediately after symptom onset would improve clinical outcomes and/or lead to post-treatment viral burden rebound due to inadequate viral clearance during treatment. Here we show that, by emulating a randomized target trial using real-world electronic medical record data from all 87,070 adult users of nirmatrelvir/ritonavir in Hong Kong between 16th March 2022 and 15th January 2023, early initiation of nirmatrelvir/ritonavir treatment (0 to 1 days after symptom onset or diagnosis) significantly reduced the incidence of 28-day all-cause mortality and hospitalization compared to delayed initiation (2 or more days) (absolute risk reduction [ARR]: 1.50% (95% confidence interval 1.17-1.80%); relative risk [RR]: 0.77 (0.73, 0.82)), but may be associated with a significant elevated risk of viral burden rebound (ARR: -1.08% (-1.55%, -0.46%)), although the latter estimates were associated with high uncertainty due to limited sample sizes. As such, patients should continue to initiate nirmatrelvir/ritonavir early after symptom onset or diagnosis to better protect against the more serious outcomes of hospitalization and mortality.

Budget impact of oral nirmatrelvir/ritonavir in adults at high risk for progression to severe COVID-19 in the United States

BACKGROUND

Nirmatrelvir/ritonavir (NMV/r) is indicated for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19. NMV/r has also been authorized for emergency use by the US Food and Drug Administration for the treatment of mild-to-moderate COVID-19 in pediatric patients (aged 226512 years and weighing at least 40 kg) who are at high risk for progression to severe COVID-19. Understanding the budget impact of introducing NMV/r for the treatment of adults with COVID-19 is of key interest to US payers.

OBJECTIVE

To estimate the annual budget impact of introducing NMV/r in a US commercial health plan setting in the current Omicron COVID-19 era.

METHODS

A budget impact model was developed to assess the impact of NMV/r on health care costs in a hypothetical 1-million-member commercial health insurance plan over a 1-year period in the US population; clinical and cost inputs were derived from published literature with a focus on studies in the recent COVID-19 era that included vaccinated population and predominance of the Omicron variant. In the base-case analysis, it was assumed the only effect of NMV/r was a reduction in incidence (not severity) of hospitalization or death; its potential effect on post-COVID conditions was assessed in a scenario analysis. Outcomes included the number of hospitalizations, total cost, per patient per year (PPPY) costs, and per member per month (PMPM) costs. Sensitivity and scenario analyses were conducted to assess uncertainty around key model inputs.

RESULTS

An estimated 29,999 adults were eligible and sought treatment with oral antiviral for COVID-19 over 1 year. The availability of NMV/r was estimated to reduce the number of hospitalizations by 647 with a total budget impact of $2,733,745, $91 PPPY, and $0.23 PMPM. NMV/r was cost saving when including post-COVID conditions with a -$1,510,780 total budget impact, a PPPY cost of -$50, and a PMPM cost of -$0.13. Sensitivity analyses indicated results were most sensitive to the risk of hospitalization under supportive care, risk of hospitalization with NMV/r treatment and cost of NMV/r.

CONCLUSIONS

Treatment with NMV/r in the current COVID-19 era is estimated to result in substantial cost offsets because of reductions in hospitalization and modest budget impact to potential overall cost savings.

Comparative effectiveness of nirmatrelvir/ritonavir versus sotrovimab and molnupiravir for preventing severe COVID-19 outcomes in non-hospitalised high-risk patients during Omicron waves: observational cohort study using the OpenSAFELY platform

Background

Timely evidence of the comparative effectiveness between COVID-19 therapies in real-world settings is needed to inform clinical care. This study aimed to compare the effectiveness of nirmatrelvir/ritonavir versus sotrovimab and molnupiravir in preventing severe COVID-19 outcomes in non-hospitalised high-risk COVID-19 adult patients during Omicron waves.

Methods

With the approval of NHS England, we conducted a real-world cohort study using the OpenSAFELY-TPP platform. Patient-level primary care data were obtained from 24 million people in England and were securely linked with data on COVID-19 infection and therapeutics, hospital admission, and death, covering a period where both nirmatrelvir/ritonavir and sotrovimab were first-line treatment options in community settings (February 10, 2022-November 27, 2022). Molnupiravir (third-line option) was used as an exploratory comparator to nirmatrelvir/ritonavir, both of which were antivirals. Cox proportional hazards model stratified by area was used to compare the risk of 28-day COVID-19 related hospitalisation/death across treatment groups.

Findings

A total of 9026 eligible patients treated with nirmatrelvir/ritonavir (n = 5704) and sotrovimab (n = 3322) were included in the main analysis. The mean age was 52.7 (SD = 14.9) years and 93% (8436/9026) had three or more COVID-19 vaccinations. Within 28 days after treatment initiation, 55/9026 (0.61%) COVID-19 related hospitalisations/deaths were observed (34/5704 [0.60%] treated with nirmatrelvir/ritonavir and 21/3322 [0.63%] with sotrovimab). After adjusting for demographics, high-risk cohort categories, vaccination status, calendar time, body mass index and other comorbidities, we observed no significant difference in outcome risk between nirmatrelvir/ritonavir and sotrovimab users (HR = 0.89, 95% CI: 0.48-1.63; P = 0.698). Results from propensity score weighted model also showed non-significant difference between treatment groups (HR = 0.82, 95% CI: 0.45-1.52; P = 0.535). The exploratory analysis comparing nirmatrelvir/ritonavir users with 1041 molnupiravir users (13/1041 [1.25%] COVID-19 related hospitalisations/deaths) showed an association in favour of nirmatrelvir/ritonavir (HR = 0.45, 95% CI: 0.22-0.94; P = 0.033).

Interpretation

In routine care of non-hospitalised high-risk adult patients with COVID-19 in England, no substantial difference in the risk of severe COVID-19 outcomes was observed between those who received nirmatrelvir/ritonavir and sotrovimab between February and November 2022, when Omicron subvariants BA.2, BA.5, or BQ.1 were dominant.

Funding

UK Research and Innovation, Wellcome Trust, UK Medical Research Council, National Institute for Health and Care Research, and Health Data Research UK.

Effectiveness of Nirmatrelvir-Ritonavir Against the Development of Post-COVID-19 Conditions Among U.S. Veterans : A Target Trial Emulation

BACKGROUND

COVID-19 has been linked to the development of many post-COVID-19 conditions (PCCs) after acute infection. Limited information is available on the effectiveness of oral antivirals used to treat acute COVID-19 in preventing the development of PCCs.

OBJECTIVE

To measure the effectiveness of outpatient treatment of COVID-19 with nirmatrelvir-ritonavir in preventing PCCs.

DESIGN

Retrospective target trial emulation study comparing matched cohorts receiving nirmatrelvir-ritonavir versus no treatment.

SETTING

Veterans Health Administration (VHA).

PARTICIPANTS

Nonhospitalized veterans in VHA care who were at risk for severe COVID-19 and tested positive for SARS-CoV-2 during January through July 2022.

INTERVENTION

Nirmatrelvir-ritonavir treatment for acute COVID-19.

MEASUREMENTS

Cumulative incidence of 31 potential PCCs at 31 to 180 days after treatment or a matched index date, including cardiac, pulmonary, renal, thromboembolic, gastrointestinal, neurologic, mental health, musculoskeletal, endocrine, and general conditions and symptoms.

RESULTS

Eighty-six percent of the participants were male, with a median age of 66 years, and 17.5% were unvaccinated. Baseline characteristics were well balanced between participants treated with nirmatrelvir-ritonavir and matched untreated comparators. No differences were observed between participants treated with nirmatrelvir-ritonavir (n = 9593) and their matched untreated comparators in the incidence of most PCCs examined individually or grouped by organ system, except for lower combined risk for venous thromboembolism and pulmonary embolism (subhazard ratio, 0.65 [95% CI, 0.44 to 0.97]; cumulative incidence difference, -0.29 percentage points [CI, -0.52 to -0.05 percentage points]).

LIMITATIONS

Ascertainment of PCCs using International Classification of Diseases, 10th Revision, codes may be inaccurate. Evaluation of many outcomes could have resulted in spurious associations with combined thromboembolic events by chance.

CONCLUSION

Out of 31 potential PCCs, only combined thromboembolic events seemed to be reduced by nirmatrelvir-ritonavir.

PRIMARY FUNDING SOURCE

U.S. Department of Veterans Affairs.

Oral Molnupiravir and Nirmatrelvir/Ritonavir for the Treatment of COVID-19: A Literature Review with a Focus on Real-World Evidence

Vaccines remain the cornerstone of medical prevention and are highly effective in reducing the risk of severe disease and death due to coronavirus disease 2019 (COVID-19). In the context of expanding the therapeutic armamentarium against COVID-19, molnupiravir (Lagevrio) and ritonavir-boosted nirmatrelvir (Paxlovid) were developed, constituting the first effective oral treatments against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this narrative review, we retrospectively inquired into the clinical trials and real-world studies investigating the efficacy of these agents. Overall, clinical trials and real-world studies have demonstrated the efficacy of both agents in reducing hospitalization and death rates in COVID-19 patients. As per current recommendations, their use is suggested in patients with mild to moderate symptoms who are at high risk of developing severe disease. Nevertheless, limited data exist regarding their efficacy in specific subpopulations, such as immunocompromised patients, those with severe kidney disease, pregnant women, and children.

Effectiveness of molnupiravir vs nirmatrelvir-ritonavir in non-hospitalised and hospitalised patients with COVID-19: a target trial emulation study

Background

Molnupiravir and nirmatrelvir-ritonavir have emerged as promising options for COVID-19 treatment, but direct comparisons of their effectiveness have been limited. This study aimed to compare the effectiveness of these two oral antiviral drugs in non-hospitalised and hospitalised patients with COVID-19.

Methods

In this target trial emulation study, we used data from a territory-wide electronic health records database on eligible patients aged ≥18 years infected with COVID-19 who were prescribed either molnupiravir or nirmatrelvir-ritonavir within five days of infection between 16 March 2022 and 31 December 2022 in the non-hospitalised and hospitalised settings in Hong Kong. A sequence trial approach and 1:1 propensity score matching was applied based on age, sex, number of COVID-19 vaccine doses received, Charlson comorbidity index, comorbidities, and drug use within past 90 days. Cox regression adjusted with patients' characteristics was used to compare the risk of effectiveness outcomes (all-cause mortality, intensive care unit (ICU) admission or ventilatory support and hospitalisation) between groups. Subgroup analyses included age (<70; ≥70 years); sex, Charlson comorbidity index (<4; ≥4), and number of COVID-19 vaccine doses received (0-1; ≥2 doses).

Findings

A total of 63,522 non-hospitalised (nirmatrelvir-ritonavir: 31,761; molnupiravir: 31,761) and 11,784 hospitalised (nirmatrelvir-ritonavir: 5892; molnupiravir: 5892) patients were included. In non-hospitalised setting, 336 events of all-cause mortality (nirmatrelvir-ritonavir: 71, 0.22%; molnupiravir: 265, 0.83%), 162 events of ICU admission or ventilatory support (nirmatrelvir-ritonavir: 71, 0.22%; molnupiravir: 91, 0.29%), and 4890 events of hospitalisation (nirmatrelvir-ritonavir: 1853, 5.83%; molnupiravir: 3037, 9.56%) were observed. Lower risks of all-cause mortality (absolute risk reduction (ARR) at 28 days: 0.61%, 95% CI: 0.50-0.72; HR: 0.43, 95% CI: 0.33-0.56) and hospital admission (ARR at 28 days: 3.73%, 95% CI: 3.31-4.14; HR: 0.72, 95% CI: 0.67-0.76) were observed in nirmatrelvir-ritonavir users compared to molnupiravir users. In hospitalised setting, 509 events of all-cause mortality (nirmatrelvir-ritonavir: 176, 2.99%; molnupiravir: 333, 5.65%), and 50 events of ICU admission or ventilatory support (nirmatrelvir-ritonavir: 26, 0.44%; molnupiravir: 24, 0.41%) were observed. Risk of all-cause mortality was lower for nirmatrelvir-ritonavir users than for molnupiravir users (ARR at 28 days: 2.66%, 95% CI: 1.93-3.40; HR: 0.59, 95% CI: 0.49-0.71). In both settings, there was no difference in the risk of intensive care unit admission or ventilatory support between groups. The findings were consistent across all subgroup's analyses.

Interpretation

Our analyses suggest that nirmatrelvir-ritonavir was more effective than molnupiravir in reducing the risk of all-cause mortality in both non-hospitalised and hospitalised patients. When neither drug is contraindicated, nirmatrelvir-ritonavir may be considered the more effective option.

Funding

HMRF Research on COVID-19, The Hong Kong Special Administrative Region (HKSAR) Government; Collaborative Research Fund, University Grants Committee, the HKSAR Government; and Research Grant from the Food and Health Bureau, the HKSAR Government; the Laboratory of Data Discovery for Health (D24H) funded by the AIR@InnoHK administered by Innovation and Technology Commission.

Drug treatment for Covid-19 - three years later

There has been a profusion of trials for SARS CoV2 drugs. A review dating from May 2020 listed 115 medicines, most of which previously existed, having been investigated since the onset of the pandemic. Over an exceedingly short lapse of time, the perspective of the arrival of a new antiviral treatment specifically targeting COVID-19 appeared highly improbable. Three years later, only one treatment is recommended in France: the nirmatrelvir + ritonavir combination. While remdesivir remains available, it is only proposed when this combination is officially contraindicated. Three monoclonal antibodies, taken alone or in association, are currently available in France:: tixagevimab/cilgavimab, casirivimab/imdevimab and sotrovimab. While all three of them have received European market authorization for patients presenting with an increased risk of evolution toward a severe form of COVID-19, and while early access is possible, they are no longer recommended, the reason being a loss or alteration of activity on variants carrying a Spike protein mutation. RoActemra is a humanized monoclonal antibody that blocks the action of interleukin 6 receptors; it is exclusively reserved for adult patients receiving systemic corticotherapy and necessitating oxygen supplementation, while patients under invasive mechanical ventilation are excluded. All in all, since the onset of the pandemic dozens of products have been subjected to tests or trials; three years later, only a highly limited number of "candidates" remain, and definitive assessment has yet to be achieved.

Real-world nirmatrelvir-ritonavir outpatient treatment in reducing hospitalization for high-risk patients with COVID-19 during Omicron BA.4, BA.5 and XBB subvariants dominance in Malaysia: A retrospective cohort study

OBJECTIVE

To determine if nirmatrelvir-ritonavir 300mg/100mg treatment for 5 days in high-risk outpatients with mild to moderate COVID-19 symptoms was associated with a reduction in hospitalization, intensive care unit (ICU) admission, and death.

METHODS

This 1:1 propensity score matched cohort study from 647 public health clinics in Malaysia included all patients with COVID-19 with positive tests aged 18 years and older, who were eligible for nirmatrelvir-ritonavir treatment within 5 days of illness from July 14, 2022, to November 14, 2022. The exposed group was patients with COVID-19 initiated with nirmatrelvir-ritonavir treatment, whereas those not initiated with the drug served as the control group. Data was analyzed from July 14, 2022 to December 31, 2022.

RESULTS

A total of 20,966 COVID-19 high-risk outpatients (n = 10,483 for nirmatrelvir-ritonavir group and n = 10,483 for control group) were included in the study. Nirmatrelvir-ritonavir treatment was associated with a 36% reduction (adjusted hazard ratio 0.64 [95% CI 0.43, 0.94]) in hospitalization compared with those not given the drug. There was a single ICU admission for the control group and one death each was reported in the nirmatrelvir-ritonavir and control group, respectively.

CONCLUSIONS

Nirmatrelvir-ritonavir treatment was associated with reduced hospitalization in high-risk patients with COVID-19 even in highly vaccinated populations.

Real-World Effectiveness of Nirmatrelvir/Ritonavir on Coronavirus Disease 2019-Associated Hospitalization Prevention: A Population-based Cohort Study in the Province of Quebec, Canada

BACKGROUND

Nirmatrelvir/ritonavir has shown to reduce COVID-19 hospitalization and death before Omicron, but updated real-world evidence studies are needed. This study aimed to assess whether nirmatrelvir/ritonavir reduces the risk of COVID-19-associated hospitalization among high-risk outpatients.

METHODS

A retrospective cohort study of outpatients with SARS-CoV-2 between March 15 and 15 October 2022, using data from the Quebec clinico-administrative databases. Outpatients treated with nirmatrelvir/ritonavir were compared with infected ones not receiving nirmatrelvir/ritonavir using propensity-score matching. Relative risk (RR) of COVID-19-associated hospitalization within 30 days was assessed using a Poisson regression.

RESULTS

A total of 8402 treated outpatients were matched to controls. Regardless of vaccination status, nirmatrelvir/ritonavir treatment was associated with a 69% reduced RR of hospitalization (RR: .31; 95% CI: .28; .36; number needed to treat [NNT] = 13). The effect was more pronounced in outpatients with incomplete primary vaccination (RR: .04; 95% CI: .03; .06; NNT = 8), while no benefit was found in those with a complete primary vaccination (RR: .93; 95% CI: .78; 1.08). Subgroups analysis among high-risk outpatients with a complete primary vaccination showed that nirmatrelvir/ritonavir treatment was associated with a significant decrease in the RR of hospitalization in severely immunocompromised outpatients (RR: .66; 95% CI: .50; .89; NNT = 16) and in high-risk outpatients aged ≥70 years (RR: .50; 95% CI: .34; .74; NNT = 10) when the last dose of the vaccine was received at least 6 months ago.

CONCLUSIONS

Nirmatrelvir/ritonavir reduces the risk of COVID-19-associated hospitalization among incompletely vaccinated high-risk outpatients and among some subgroups of completely vaccinated high-risk outpatients.

Nirmatrelvir/ritonavir for the treatment of immunocompromised adult patients with early-stage symptomatic COVID-19: A real-life experience

Regardless of vaccination status, progression to severe coronavirus disease 2019 (COVID-19) is still a relevant cause of morbidity among immunocompromised patients. Despite the proven efficacy of nirmatrelvir/ritonavir (NMV/r), concerns remain regarding the potential for drug-to-drug interactions (DDIs) and the safety in this at-risk population. We aimed to evaluate the clinical outcomes of immunocompromised patients treated with NMV/r, as well as the occurrence of DDIs and treatment-emergent adverse events (TEAEs). This retrospective observational study included all the patients with some form of immunosuppression and laboratory-confirmed COVID-19 that received NMV/r at our center from April to August 2022. The main outcome was worsening of the clinical status (increase of ≥1 point from baseline in a validated clinical progression scale) by Days +7 and +28 after the initiation of therapy. Safety outcomes included the rates of any TEAE and potentially severe DDIs. We included 110 patients. Main causes of immunosuppression were hematological malignancy (58.2%) (mainly multiple myeloma [22.7%] and non-Hodgkin lymphoma [13.6%]), active chemotherapy (30.0%) and hematopoietic stem cell transplantation (14.5%). Clinical worsening by Days +7 and +28 was observed in four (3.6%) and five patients (4.5%), respectively. Only one patient had a positive SARS-CoV-2 polymerase chain reaction test at Day +28. At least one potentially severe DDI was observed in 56.4% of the patients. The rate of attributable TEAEs was 10.9%, although only two patients (1.8%) required premature discontinuation of NMV/r. Early initiation of NMV/r therapy should be considered in immunocompromised patients with COVID-19, with particular attention to interacting medications.

Monoclonal Antibody and Oral Antiviral Treatment of SARS-CoV-2 Infection in US Nursing Homes

This study examines the use of COVID-19 antiviral treatments in US nursing homes and the facility characteristics associated with use of oral antivirals and monoclonal antibodies.

Anti-SARS-CoV-2 Pharmacotherapies Among Nonhospitalized US Veterans, January 2022 to January 2023

Importance

Several pharmacotherapies have been authorized to treat nonhospitalized persons with symptomatic COVID-19. Longitudinal information on the use of these therapies is needed.

Objective

To analyze trends and factors associated with prescription of outpatient COVID-19 pharmacotherapies within the Veterans Health Administration (VHA).

Design, Setting, and Participants

This cohort study evaluated nonhospitalized veterans in VHA care who tested positive for SARS-CoV-2 from January 2022 through January 2023 using VHA and linked Community Care and Medicare databases.

Exposures

Demographic characteristics, underlying medical conditions, COVID-19 vaccination, and regional and local systems of care, including Veterans Integrated Services Networks (VISNs).

Main Outcomes and Measures

Monthly receipt of any COVID-19 pharmacotherapy (nirmatrelvir-ritonavir, molnupiravir, sotrovimab, or bebtelovimab) was described. Multivariable logistic regression was used to identify factors independently associated with receipt of any vs no COVID-19 pharmacotherapy.

Results

Among 285 710 veterans (median [IQR] age, 63.1 [49.9-73.7] years; 247 358 males [86.6%]; 28 444 Hispanic [10.0%]; 61 269 Black [21.4%] and 198 863 White [69.6%]) who tested positive for SARS-CoV-2 between January 2022 and January 2023, the proportion receiving any pharmacotherapy increased from 3285 of 102 343 veterans (3.2%) in January 2022 to 5180 of 21 688 veterans (23.9%) in August 2022. The proportion declined to 2194 of 10 551 veterans (20.8%) by January 2023. Across VISNs, the range in proportion of patients who tested positive who received nirmatrelvir-ritonavir or molnupiravir during January 2023 was 41 of 692 veterans (5.9%) to 106 of 494 veterans (21.4%) and 2.1% to 120 of 1074 veterans (11.1%), respectively. Veterans receiving any treatment were more likely to be older (adjusted odds ratio [aOR] for ages 65-74 vs 50-64 years, 1.18; 95% CI, 1.14-1.22; aOR for ages ≥75 vs 50-64 years, 1.19; 95% CI, 1.15-1.23) and have a higher Charlson Comorbidity Index score (aOR for CCI ≥6 vs 0, 1.52; 95% CI, 1.44-1.59). Compared with White veterans, Black veterans (aOR, 1.06; 95% CI, 1.02-1.09) were more likely to receive treatment, and compared with non-Hispanic veterans, Hispanic veterans (aOR 1.06; 95% CI, 1.01-1.11) were more likely to receive treatment.

Conclusions And Relevance

This study found that prescription of outpatient COVID-19 pharmacotherapies in the VHA peaked in August 2022 and declined thereafter. There were large regional differences in patterns of nirmatrelvir-ritonavir and molnupiravir use.

Increased vaccine sensitivity of an emerging SARS-CoV-2 variant

Host immune responses are a key source of selective pressure driving pathogen evolution. Emergence of many SARS-CoV-2 lineages has been associated with enhancements in their ability to evade population immunity resulting from both vaccination and infection. Here we show diverging trends of escape from vaccine-derived and infection-derived immunity for the emerging XBB/XBB.1.5 Omicron lineage. Among 31,739 patients tested in ambulatory settings in Southern California from December, 2022 to February, 2023, adjusted odds of prior receipt of 2, 3, 4, and ≥5 COVID-19 vaccine doses were 10% (95% confidence interval: 1-18%), 11% (3-19%), 13% (3-21%), and 25% (15-34%) lower, respectively, among cases infected with XBB/XBB.1.5 than among cases infected with other co-circulating lineages. Similarly, prior vaccination was associated with greater point estimates of protection against progression to hospitalization among cases with XBB/XBB.1.5 than among non-XBB/XBB.1.5 cases (70% [30-87%] and 48% [7-71%], respectively, for recipients of ≥4 doses). In contrast, cases infected with XBB/XBB.1.5 had 17% (11-24%) and 40% (19-65%) higher adjusted odds of having experienced 1 and ≥2 prior documented infections, respectively, including with pre-Omicron variants. As immunity acquired from SARS-CoV-2 infection becomes increasingly widespread, fitness costs associated with enhanced vaccine sensitivity in XBB/XBB.1.5 may be offset by increased ability to evade infection-derived host responses.

Paxlovid (nirmatrelvir/ritonavir) effectiveness against hospitalization and death in N3C: A target trial emulation study

Importance

COVID-19 has placed a monumental burden on the health care system globally. Although no longer a public health emergency, there is still a pressing need for effective treatments to prevent hospitalization and death. Paxlovid (nirmatrelvir/ritonavir) is a promising and potentially effective antiviral that has received emergency use authorization by the U.S. FDA.

Objective

Determine real world effectiveness of Paxlovid nationwide and investigate disparities between treated and untreated eligible patients.

Design/Setting/Participants

Population-based cohort study emulating a target trial, using inverse probability weighted models to balance treated and untreated groups on baseline confounders. Participants were patients with a SARS-CoV-2 positive test or diagnosis (index) date between December 2021 and February 2023 selected from the National COVID Cohort Collaborative (N3C) database who were eligible for Paxlovid treatment. Namely, adults with at least one risk factor for severe COVID-19 illness, no contraindicated medical conditions, not using one or more strictly contraindicated medications, and not hospitalized within three days of index. From this cohort we identified patients who were treated with Paxlovid within 5 days of positive test or diagnosis (n = 98,060) and patients who either did not receive Paxlovid or were treated outside the 5-day window (n = 913,079 never treated; n = 1,771 treated after 5 days).

Exposures

Treatment with Paxlovid within 5 days of positive COVID-19 test or diagnosis.

Main Outcomes and Measures

Hospitalization and death in the 28 days following COVID-19 index date.

Results

A total of 1,012,910 COVID-19 positive patients at risk for severe COVID-19 were included, 9.7% of whom were treated with Paxlovid. Uptake varied widely by geographic region and timing, with top adoption areas near 50% and bottom near 0%. Adoption increased rapidly after EUA, reaching steady state by 6/2022. Participants who were treated with Paxlovid had a 26% (RR, 0.742; 95% CI, 0.689-0.812) reduction in hospitalization risk and 73% (RR, 0.269, 95% CI, 0.179-0.370) reduction in mortality risk in the 28 days following COVID-19 index date.

Conclusions/Relevance

Paxlovid is effective in preventing hospitalization and death in at-risk COVID-19 patients. These results were robust to a large number of sensitivity considerations.

Disclosure

The authors report no disclosures.

Key points

Question: Is treatment with Paxlovid (nirmatrelvir/ritonavir) associated with a reduction in 28-day hospitalization and mortality in patients at risk for severe COVID-19? Findings: In this multi-institute retrospective cohort study of 1,012,910 patients, Paxlovid treatment within 5 days after COVID-19 diagnosis reduced 28-day hospitalization and mortality by 26% and 73% respectively, compared to no treatment with Paxlovid within 5 days. Paxlovid uptake was low overall (9.7%) and highly variable. Meaning: In Paxlovid-eligible patients, treatment was associated with decreased risk of hospitalization and death. Results align with prior randomized trials and observational studies, thus supporting the real-world effectiveness of Paxlovid.

The impact of vaccination and outpatient treatment on the economic burden of Covid-19 in the United States omicron era: a systematic literature review

AIMS

To identify and synthesize evidence regarding how coronavirus disease 2019 (COVID-19) interventions, including vaccines and outpatient treatments, have impacted healthcare resource use (HCRU) and costs in the United States (US) during the Omicron era.

MATERIALS AND METHODS

A systematic literature review (SLR) was performed to identify articles published between 1 January 2021 and 10 March 2023 that assessed the impact of vaccination and outpatient treatment on costs and HCRU outcomes associated with COVID-19. Screening was performed by two independent researchers using predefined inclusion/exclusion criteria.

RESULTS

Fifty-eight unique studies were included in the SLR, of which all reported HCRU outcomes, and one reported costs. Overall, there was a significant reduction in the risk of COVID-19-related hospitalization for patients who received an original monovalent primary series vaccine plus booster dose vs. no vaccination. Moreover, receipt of a booster vaccine was associated with a lower risk of hospitalization vs. primary series vaccination. Evidence also indicated a significantly reduced risk of hospitalizations among recipients of nirmatrelvir/ritonavir (NMV/r), remdesivir, sotrovimab, and molnupiravir compared to non-recipients. Treated and/or vaccinated patients also experienced reductions in intensive care unit (ICU) admissions, length of stay, and emergency department (ED)/urgent care clinic encounters.

LIMITATIONS

The identified studies may not represent unique patient populations as many utilized the same regional/national data sources. Synthesis of the evidence was also limited by differences in populations, outcome definitions, and varying duration of follow-up across studies. Additionally, significant gaps, including HCRU associated with long COVID and various high-risk populations and cost data, were observed.

CONCLUSIONS

Despite evidence gaps, findings from the SLR highlight the significant positive impact that vaccination and outpatient treatment have had on HCRU in the US, including periods of Omicron predominance. Continued research is needed to inform clinical and policy decision-making in the US as COVID-19 continues to evolve as an endemic disease.