Search Results (113)

Introduction: The emergence of SARS-CoV-2 Omicron subvariants characterized by increased transmissibility and immune escape has raised concerns about the efficacy of current treatments. This systematic review and meta-analysis evaluated pharmacological and non-pharmacological interventions in Omicron-infected non-hospitalized patients, focusing on key clinical outcomes such as hospitalization, respiratory failure, ICU admission, and 30-day mortality. Methods: Searches were performed in MEDLINE, EMBASE, Web of Science, Cochrane, and ClinicalTrials.gov (last update: 13 July 2025). Eligible studies reported outcomes on antiviral agents, monoclonal antibodies, adjunctive therapies, or telemedicine. Random-effects meta-analyses were conducted when appropriate, with heterogeneity assessed by I². Publication bias was evaluated via funnel plots and Egger’s test. Subgroup analyses explored sources of heterogeneity. Results: Eighty-eight studies were included. Meta-analyses, comparing treatment vs. no treatment, revealed that nirmatrelvir/ritonavir reduced hospitalization by 52% (RR 0.48, 95% CI 0.36–0.63) and all-cause mortality by 84% (RR 0.16, 95% CI 0.11–0.24). Remdesivir reduced hospitalization by 70% (RR 0.30, 95% CI 0.19–0.47) and respiratory failure by 89% (RR 0.11, 95% CI 0.03–0.44). Sotrovimab decreased hospitalization (RR 0.71, 95% CI 0.54–0.93) and mortality (RR 0.34, 95% CI 0.19–0.61). Molnupiravir modestly reduced hospitalization (RR 0.80, 95% CI 0.70–0.91) and respiratory failure (RR 0.45, 95% CI 0.27–0.77). Conclusions: Nirmatrelvir/ritonavir and remdesivir remain important for reducing severe outcomes, while sotrovimab retains partial efficacy. Rapid access to antivirals remains an important factor in mitigating SARS-CoV-2’s burden. Full article

The cross-species spillover of coronaviruses is considered a serious public health risk. Feline coronavirus (FCoV), canine coronavirus (CCoV), and transmissible gastroenteritis virus (TGEV) are all classified under Alphacoronavirus suis and infect companion animals and livestock. Due to their frequent contact with humans, these viruses pose a potential risk of future cross-species transmission. Molnupiravir, a prodrug of N4-hydroxycytidine, exhibits potent antiviral activity against SARS-CoV-2, a member of the Betacoronavirus genus, and has been approved for the treatment of COVID-19. Molnupiravir was recently shown to be effective against FCoV, suggesting broad-spectrum antiviral activity across coronavirus lineages. Based on these findings, the present study investigated whether molnupiravir is also effective against CCoV and TGEV, which belong to the same Alphacoronavirus suis species as FCoV. We examined the in vitro antiviral effects of molnupiravir using four viral strains: FCoV-1 and -2, CCoV-2, and TGEV. Molnupiravir inhibited plaque formation, viral antigen expression, the production of infectious viral particles, and viral RNA replication in a dose-dependent manner in all strains. IC₅₀ values for CCoV-2 and TGEV, calculated using a feline-derived cell line (fcwf-4), were significantly lower than those for FCoV, suggesting higher sensitivity to molnupiravir. These results demonstrate that molnupiravir exhibited broad antiviral activity against animal coronaviruses classified under Alphacoronavirus suis, providing a foundation for antiviral strategies to mitigate the future risk of cross-species transmission. Full article

Coronavirus disease 2019 (COVID-19) causes cardiovascular complications, which contributes to the high mortality rate of the disease. Emerging evidence indicates that aberrant vascular smooth muscle cell (SMC) function is a key driver of vascular disease in COVID-19. While antivirals alleviate the symptoms of COVID-19, it is not known whether these drugs directly affect SMCs. Accordingly, the present study investigated the ability of three approved COVID-19 antiviral drugs to influence SMC function. Treatment of SMCs with remdesivir (RDV), but not molnupiravir or nirmatrelvir, inhibited cell proliferation, DNA synthesis, and migration without affecting cell viability. RDV also stimulated an increase in heme oxygenase-1 (HO-1) expression that was not observed with molnupiravir or nirmatrelvir. The induction of HO-1 by RDV was abolished by mutating the antioxidant responsive element of the promoter, overexpressing dominant-negative NF-E2-related factor-2 (Nrf2), or treating cells with an antioxidant. Finally, silencing HO-1 partly rescued the proliferative and migratory response of RDV-treated SMCs, and this was reversed by carbon monoxide and bilirubin. In conclusion, the induction of HO-1 via the oxidant-sensitive Nrf2 signaling pathway contributes to the antiproliferative and antimigratory actions of RDV by generating carbon monoxide and bilirubin. These pleiotropic actions of RDV may prevent occlusive vascular disease in COVID-19. Full article

Since the onset of the COVID-19 pandemic, remarkable progress has been made in the development of antiviral therapies for SARS-CoV-2. Several direct-acting antivirals, such as remdesivir, molnupiravir, and nirmatrelvir/ritonavir, offer clinical benefits. These agents have significantly contributed to reducing the viral loads and duration of the illness, as well as the disease’s severity and mortality. However, despite these advances, important limitations remain. The continued emergence of resistant SARS-CoV-2 variants highlights the urgent need for adaptable and durable therapeutic strategies. Therefore, this review aims to provide an updated overview of the main antiviral strategies that are used and the discovery of new drugs against SARS-CoV-2, as well as the therapeutic limitations that have shaped clinical management in recent years. The major challenges include resistance associated with viral mutations, limited treatment windows, and unequal access to treatment. Moreover, there is an ongoing need to identify novel compounds with broad-spectrum activity, improved pharmacokinetics, and suitable safety profiles. Combination treatment regimens represent a promising strategy to increase the efficacy of treating COVID-19 while minimizing the potential for resistance. Ideally, these interventions should be safe, affordable, and easy to administer, which would ensure broad global access and equitable treatment and enable control of COVID-19 cases and preparedness for future threats. Full article

Feline infectious peritonitis (FIP) is a severe viral disease with a very high fatality rate. GS-441524 is an adenosine analogue that acts as an antiviral and has shown promise in FIP treatment. However, its commercialization in some regions is not yet authorized. To evaluate the efficacy of GS-441524 based on the published literature, a systematic review was conducted. This systematic review was conducted using PubMed, ScienceDirect, and Google Scholar for studies published from 2018 onwards. Following PRISMA guidelines, 11 studies (totaling 650 FIP cases treated with GS-441524 alone or in combination) were included. Therapeutic efficacy was assessed by FIP form, clinical signs, and dosage. The overall treatment success rate was 84.6%. This rate was higher when GS-441524 was combined with other antivirals and lower in cases of wet FIP or those with neurological complications. Combination therapy with other antivirals may improve outcomes in complicated FIP cases, although further studies are needed. The GS-441524 dosages associated with the best outcomes were 5–10 mg/kg once daily (or equivalent subcutaneous dose), adjusted for FIP type, severity, and presence of neurological/ocular signs. Higher dosages can be used for severe cases or to prevent relapse, but splitting into twice-daily dosing may be necessary to avoid absorption issues. In summary, this synthesis indicates that GS-441524 is a highly promising treatment for FIP, with a high success rate among treated cases. Nevertheless, randomized controlled trials are needed to establish evidence-based therapeutic protocols tailored to different FIP presentations. Full article

Influenza and SARS-CoV-2 are often associated with viral pneumonia, resulting from direct exposure of the virus to lung tissue. 3,3′-Diindolylmethane (DIM) is a naturally occurring substance with multi-target activity, including anti-inflammatory and epigenetic modulation. In this study, we evaluated the therapeutic efficacy in vivo of a DIM formulation with fish oil (Cesarox Epi) against influenza A (H1N1) infection in mice and against SARS-CoV-2 infection in Syrian hamsters. In a model of lethal influenza pneumonia induced by A/California/04/2009 (H1N1)pdm09 virus, we showed that 5 days’ treatment with DIM Epi at 10, 20, and 60 mg/kg/day delayed the time to death, prevented body weight loss, and resulted in significant improvements in survival. DIM Epi tested in hamsters infected with SARS-CoV2 Dubrovka (Wuhan-like) strain at doses 50 and 100 mg/kg/day reduced clinical signs, weight loss, temperature elevation, and lung pathology. In both models of infections, treatment with DIM Epi did not significantly decrease viral titer in the animals’ lungs. DIM Epi and Oseltamivir were more effective against influenza infection when given in combination than given singly, while co-administration of DIM Epi with Molnupiravir did not yield an additive benefit against SARS-CoV-2 infection. These findings support DIM Epi as a promising host-directed adjunct therapy for viral pneumonia with potential to enhance outcomes in respiratory infections. Full article

Antiviral drugs like EIDD-2801 (molnupiravir; MPV) have been successfully used in the treatment of feline infectious peritonitis (FIP). The previous study of the pharmacokinetics of MPV in healthy cats showed promise for its use and safety. The objective was to determine the pharmacokinetics of molnupiravir in cats with naturally occurring FIP by measuring MPV and EIDD-193 (β-D-N4-hydroxycytidine; NHC) serum levels. Blood was collected from seven cats diagnosed with naturally occurring FIP treated at 1, 2, 4, 6 and 12 h post oral MPV administration and at 12 h post pill administration 7 days later. Serum concentrations of MPV and NHC were determined using a previously published high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) method. The mean dose of MPV was 15.44 mg/kg (SD ± 1.82). The mean peak serum concentration of MPV (C_max) after a single PO dose of MPV was 38 ng/mL (SD ± 5). The mean peak serum concentration of NHC (C_max) after a single PO dose of MVP was 1551 ng/mL (SD ± 720). the time to reach NHC C_max (T_max) was 2.6 h (SD ± 1.4), and the NHC elimination half-life was 1.6 h (SD ± 1.1). Minimal drug accumulation was seen in trough concentrations following twice-daily dosing for 7 days. The low MPV levels may be explained by fast conversion to its active metabolite NHC. The mean NHC concentrations at all time points were at least 4 times the reported in vitro IC₅₀ for feline coronavirus strains and twice-daily dosing for seven days did not lead to drug accumulation within the serum. The results support the use of MPV in the treatment of FIP, and if therapeutic drug monitoring is to be performed, NHC should be measured. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, remains a major global health threat. The virus enters host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor. Several small-molecule antiviral drugs, including molnupiravir, favipiravir, remdesivir, and nirmatrelvir have been shown to inhibit SARS-CoV-2 replication and are approved for treating SARS-CoV-2 infections. Nirmatrelvir inhibits the viral main protease (M^pro), a key enzyme for processing polyproteins in viral replication. In contrast, molnupiravir, favipiravir, and remdesivir are prodrugs that target RNA-dependent RNA polymerase (RdRp), which is crucial for genome replication and subgenomic RNA production. However, undergoing extensive metabolism profoundly impacts their therapeutic effects. Carboxylesterases (CES) are a family of enzymes that play an essential role in the metabolism of many drugs, especially prodrugs that require activation through hydrolysis. Molnupiravir is activated by carboxylesterase-2 (CES2), while remdesivir is hydrolytically activated by CES1 but inhibits CES2. Nirmatrelvir and remdesivir are oxidized by the same cytochrome P450 (CYP) enzyme. Additionally, various transporters are involved in the uptake or efflux of these drugs and/or their metabolites. It is well established that drug-metabolizing enzymes and transporters are differentially expressed depending on the cell type, and these genes exhibit significant polymorphisms. In this review, we examine how CES-related cellular and genetic factors influence the therapeutic activities of these widely used COVID-19 medications. This article highlights implications for improving product design, targeted inhibition, and personalized medicine by exploring genetic variations and their impact on drug metabolism and efficacy. Full article

The replication machinery of SARS-CoV-2 is a primary target for therapeutic intervention, and has led to significant progress in antiviral medication discovery. This review consolidates contemporary molecular insights into viral replication and rigorously assesses treatment methods at different phases of viruses’ clinical development. Direct-acting antivirals, such as nucleoside analogs (e.g., remdesivir, molnupiravir) and protease inhibitors (e.g., nirmatrelvir), have shown clinical effectiveness in diminishing morbidity and hospitalization rates. Simultaneously, host-targeted medicines like baricitinib, camostat, and brequinar leverage critical host–virus interactions, providing additional pathways to reduce viral replication while possibly minimizing the development of resistance. Notwithstanding these advancements, constraints in distribution methods, antiviral longevity, and the risk of mutational evasion demand novel strategies. Promising investigational approaches encompass CRISPR-mediated RNA degradation systems, inhalable siRNA-nanoparticle conjugates, and molecular glue degraders that target host and viral proteins. Furthermore, next-generation treatments aimed at underutilized enzyme domains (e.g., NiRAN, ExoN) and host chaperone systems (e.g., TRiC complex) signify a transformative approach in antiviral targeting. The integration of high-throughput phenotypic screening, AI-driven medication repurposing, and systems virology is transforming the antiviral discovery field. An ongoing interdisciplinary endeavor is necessary to convert these findings into versatile, resistance-resistant antiviral strategies that are applicable beyond the present pandemic and in future coronavirus epidemics. Full article

Nipah virus (NiV), a highly lethal zoonotic pathogen causing encephalitis and respiratory diseases with mortality rates up to 40–70%, faces research limitations due to its strict biosafety level 4 (BSL-4) containment requirements, hindering antiviral development. To address this, we generated two NiV minigenome replicons (Fluc- and EGFP-based) expressed via helper plasmids encoding viral N, P, and L proteins, enabling replication studies under BSL-2 conditions. The minigenome replicon recapitulated the cytoplasmic inclusion body (IB) formation observed in live NiV infections. We further demonstrated that IB assembly is driven by liquid–liquid phase separation (LLPS), with biochemical analyses identifying the C-terminal N core domain of the N protein, as well as N₀ and XD domains and the intrinsically disordered region (IDR) of the P protein, as essential structural determinants for LLPS-mediated IB biogenesis. The targeted siRNA silencing of the 5′ and 3′ untranslated regions (UTRs) significantly reduced replicon-derived mRNA levels, validating the regulatory roles of these regions. Importantly, the minigenome replicon demonstrated sensitivity to type I/II/III interferons and antivirals (remdesivir, azvudine, molnupiravir), establishing its utility for drug screening. This study provides a safe and efficient platform for investigating NiV replication mechanisms and accelerating therapeutic development, circumventing the constraints of BSL-4 facilities while preserving key virological features. Full article

We conducted a real-life case–control study among outpatients with Omicron SARS-CoV-2 infection to assess the effectiveness of molnupiravir (MNP) in reducing hospital admission, admission to the intensive care unit, and death at day 28. Cases were SARS-CoV-2-positive patients seeking medical care within five days of symptom onset from 1 January to 31 December 2022, who received MNP. Controls were selected from a regional database among positive subjects who did not receive antiviral treatment for SARS-CoV-2. A total of 1382 patients were included (146 cases, 1236 controls). Vaccinated patients had a lower risk of mortality and of the composite outcome (hospital admission, ICU admission, or all-cause death) than unvaccinated ones (0.6% vs. 7.8%, p < 0.001 and 2% vs. 7.8%, p = 0.001, respectively). After full-matching propensity score analysis, MNP-treated subjects had a lower incidence of the composite outcome, although no effect was observed on individual outcomes. In subgroup analyses by vaccination status, MNP was effective in preventing all outcomes among unvaccinated patients and reduced the risk of ICU admission in both vaccinated and unvaccinated patients. Molnupiravir treatment effectively reduced the composite outcome risk in outpatients with SARS-CoV-2 infection, with a more pronounced benefit in unvaccinated patients. These findings highlight MNP’s potential to help prevent disease progression in high-risk patients, thereby supporting its role as an outpatient therapeutic option for COVID-19. Full article

Introduction: High-risk patients with COVID-19 benefit from early treatment to prevent severe outcomes. Sotrovimab, a monoclonal antibody, and oral antivirals such as nirmatrelvir/ritonavir and molnupiravir have been used for early intervention, but their comparative efficacy and safety, particularly during the Omicron-dominant phase, require further evaluation. Methods: A multicenter, retrospective study performed in southern Italy including all adult patients who received early antiviral treatment (sotrovimab or nirmatrelvir/r or molnupiravir) between January 2022 and February 2024 (omicron phase). Demographic, clinical, and treatment-related data were analyzed to assess primary endpoints of 28-day mortality and hospitalization. Logistic regression models identified predictors of key outcomes. Results: A total of 668 high-risk patients treated with sotrovimab (n = 326) or oral antivirals (n = 342: 69 with molnupiravir and 273 with nirmatrelvir/ritonavir) were included. There was no significant difference in 28-day mortality between groups (0.8% sotrovimab vs. 1.8% oral antivirals; p = 0.679). However, patients treated with sotrovimab exhibited a longer median time to SARS-CoV-2 negativization (13 vs. 11 days; p = 0.008) and higher non–COVID-19-related hospitalizations (2.45% vs. 0%; p = 0.003). Multivariable analysis identified cardiovascular or cerebrovascular diseases as the sole significant predictor of prolonged viral positivity (OR 1.585, 95% CI 1.072–2.345; p = 0.021). Additionally, immunocompromised status (OR 16.929, 95% CI 1.835–156.170; p = 0.013) and chronic non-COVID-19 oxygen therapy (OR 10.714, 95% CI 1.623–70.725; p = 0.014) were strongly associated with mortality. Conclusions: Sotrovimab and oral antivirals demonstrated similar efficacy in preventing mortality and hospitalization among high-risk patients. Patient-specific factors, particularly cardiovascular comorbidities and immunosuppression, significantly influenced outcomes and should guide treatment choices. Full article

Coronavirus disease 2019 (COVID-19) still causes death in elderly and immunocompromised individuals, for whom the sustainability of the vaccine response may be limited. Antiviral treatments, such as remdesivir or molnupiravir, have demonstrated limited clinical efficacy. Nirmatrelvir, an acute respiratory syndrome coronavirus 2 (SARS-CoV-2) major protease inhibitor, is clinically effective but has been associated with viral rebound and antiviral resistance. It is thus necessary to study novel and repurposed antivirals for the treatment of COVID-19. We previously demonstrated that daclatasvir (DCV), an inhibitor of the hepatitis C virus (HCV) NS5A protein, impairs SARS-CoV-2 replication by targeting viral RNA polymerase and exonuclease, but the doses of DCV used to inhibit the new coronavirus are greater than the standard human plasma exposure for hepatitis C. Because any potential use of DCV against SARS-CoV-2 would be shorter than that reported here and short-term toxicological studies on DCV show that higher doses are tolerable, we searched for doses of DCV that could protect transgenic mice expressing the human ACE2 receptor (K18-hACE-2) from lethal challenge with SARS-CoV-2. We found that a dose of 60 mg/kg/day provides this protection by reducing virus replication and virus-induced lung insult. This dose is tolerable in different animal models. Taken together, our data provide preclinical evidence that can support phase I clinical trials to confirm the safety, tolerability, and pharmacokinetics of new doses of daclatasvir for a short duration in humans to further advance this compound’s utility against COVID-19. Full article

Amidst the ongoing global challenge of the SARS-CoV-2 pandemic, the quest for effective antiviral medications remains paramount. This comprehensive review delves into the dynamic landscape of FDA-approved medications repurposed for COVID-19, categorized as antiviral and non-antiviral agents. Our focus extends beyond conventional narratives, encompassing vaccination targets, repurposing efficacy, clinical studies, innovative treatment modalities, and future outlooks. Unveiling the genomic intricacies of SARS-CoV-2 variants, including the WHO-designated Omicron variant, we explore diverse antiviral categories such as fusion inhibitors, protease inhibitors, transcription inhibitors, neuraminidase inhibitors, nucleoside reverse transcriptase, and non-antiviral interventions like importin α/β1-mediated nuclear import inhibitors, neutralizing antibodies, and convalescent plasma. Notably, Molnupiravir emerges as a pivotal player, now licensed in the UK. This review offers a fresh perspective on the historical evolution of COVID-19 therapeutics, from repurposing endeavors to the latest developments in oral anti-SARS-CoV-2 treatments, ushering in a new era of hope in the battle against the pandemic. Full article

Background. The emergence, global spread, and persistence of SARS-CoV-2 resulted in an unprecedented need for effective antiviral drugs. Throughout the pandemic, various drug development and treatment strategies were adopted, including repurposing of antivirals designed for other viruses along with a multitude of other drugs with varying mechanisms of action (MoAs). Furthermore, multidrug treatment against COVID-19 is an ongoing topic and merits further investigation. Method/Objectives. We assessed the efficacy of multidrug treatment against SARS-CoV-2 in reconstituted human nasal epithelia, using combinations of molnupiravir and nirmatrelvir as a baseline, adding suboptimal concentrations of either GS-441524 or ivermectin, attempting to increase overall antiviral activity while lowering the overall therapeutic dose. Results. Nirmatrelvir combined with molnupiravir, GS-441524, or ivermectin at suboptimal concentrations show increased antiviral activity compared to single treatment. No triple combinations showed improved inhibition of SARS-CoV-2 replication beyond what was observed for double treatments. Conclusions. In general, we observed that the addition of a third compound is not beneficial for antiviral activity, while various double combinations exhibit increased antiviral activity over single treatment. Full article