Oseltamivir in COVID-19 Treatment: Unraveling Efficacy and Safety through Systematic Review


In the unprecedented global health crisis triggered by the emergence of SARS-CoV-2, the causative agent of COVID-19, the scientific community has been in a relentless pursuit of effective treatments. The repurposing of existing drugs has emerged as a strategic approach to rapidly identify and deploy potential treatments for COVID-19, circumventing the lengthy and costly process of new drug development. Among these drugs, Oseltamivir, widely known under the brand name Tamiflu, has been under investigation for its potential efficacy against COVID-19.

Oseltamivir is a neuraminidase inhibitor that has been extensively used for the treatment and prophylaxis of influenza A and B. Its mechanism of action involves the inhibition of the neuraminidase enzyme, which is crucial for the release of new influenza virus particles from infected cells, thereby halting the spread of infection within the host.

Given its established safety profile and widespread use against influenza, researchers have explored the possibility of repurposing Oseltamivir for COVID-19 treatment. A systematic review and meta-analysis conducted according to the PRISMA guidelines evaluated the efficacy and safety of Oseltamivir in COVID-19 patients. This comprehensive analysis included studies that used Oseltamivir alone or in combination with other treatments compared to usual care, other drugs, or placebo. The primary outcome of interest was patient recovery from COVID-19, encompassing survival, clinical, virological, laboratory, radiological responses, and the duration of hospitalization. This methodological rigor aimed to synthesize available evidence and provide a grounded assessment of Oseltamivir’s role in COVID-19 management​​.

Preliminary findings from various studies present a mixed picture. One study highlighted that COVID-19 patients treated with Oseltamivir experienced a significantly shorter hospital stay and a lower death rate compared to those in the control group. However, this study also acknowledged its limitations and called for further research to elucidate the clinical benefits of Oseltamivir, especially in combination with other antiviral therapies. Another study concurred, emphasizing the inconclusive nature of the evidence regarding Oseltamivir’s effectiveness against COVID-19 and advocating for more robust, randomized controlled trials to ascertain its therapeutic value​​.

Oseltamivir’s mechanism of action, targeting the neuraminidase enzyme in influenza viruses, raises questions about its applicability to SARS-CoV-2, which is structurally and functionally distinct from influenza viruses. The effectiveness of Oseltamivir against COVID-19 would, therefore, hinge on the presence of a similar targetable mechanism or an alternative therapeutic pathway yet to be fully understood. Despite its FDA approval for treating influenza, Oseltamivir is not currently approved for the prevention or treatment of COVID-19. Ongoing clinical trials aim to determine its efficacy in reducing the severity, complications, and mortality associated with COVID-19, alongside evaluating potential side effects or unforeseen issues when used in this new context​​.

While the repurposing of Oseltamivir presents a promising avenue for COVID-19 treatment, the current body of evidence underscores the need for further clinical trials. These studies are crucial to conclusively determine Oseltamivir’s efficacy and safety profile in COVID-19 patients, potentially enabling its integration into treatment protocols if proven effective. The global scientific community remains committed to exploring every possible therapeutic option, including Oseltamivir, in the ongoing battle against COVID-19, with the ultimate goal of reducing the pandemic’s health burden.


The mechanism of oseltamivir’s action in COVID-19 patients is a complex and evolving area of research. Originally developed for the treatment of influenza, oseltamivir’s efficacy against SARS-CoV-2, the virus responsible for COVID-19, has been questioned due to the absence of viral neuraminidase, the target of oseltamivir, in the structure of SARS-CoV-2.

  • Targeting Viral Neuraminidase in Influenza: Oseltamivir, a neuraminidase inhibitor, works by targeting the neuraminidase enzyme present on the surface of influenza virus particles. Neuraminidase plays a crucial role in the influenza virus replication cycle by facilitating the release of newly formed virus particles from infected cells. By inhibiting neuraminidase, oseltamivir prevents the release of viral particles, thus slowing down the spread of the virus within the body.
  • Initial Doubts About Efficacy Against SARS-CoV-2: Given that SARS-CoV-2 does not encode neuraminidase, there were initial doubts about whether oseltamivir would be effective against COVID-19. The absence of the target enzyme raised questions about oseltamivir’s mechanism of action and its potential utility in treating COVID-19 patients.
  • Emerging Research on Neutrophil Response: Recent studies have proposed an alternative pathway through which oseltamivir may exert its effects in COVID-19 patients. This research suggests that oseltamivir could regulate the neutrophil response, thereby reducing disease severity. Neutrophils are a type of white blood cell involved in the body’s immune response to infections. However, excessive or dysregulated neutrophil activity can contribute to tissue damage and inflammation, exacerbating the severity of respiratory infections such as COVID-19.
  • Neutrophil Pathway in COVID-19: Elevated levels of neutrophils have been associated with severe cases of COVID-19. It is hypothesized that oseltamivir may modulate the activity of neutrophils, potentially attenuating the harmful effects of excessive neutrophil response in COVID-19 patients. By regulating neutrophil activity, oseltamivir could help mitigate the inflammatory cascade and reduce tissue damage in the lungs, thus improving clinical outcomes in COVID-19 patients.
  • Potential Benefits in Vaccinated Individuals: The observed additional benefits of oseltamivir in vaccinated individuals may be attributed to a weakened neutrophil response in those who have received prior vaccination against SARS-CoV-2. Vaccination primes the immune system to recognize and mount a rapid response to viral pathogens, including SARS-CoV-2. As a result, vaccinated individuals may exhibit a more controlled immune response upon infection, potentially reducing the severity of inflammation and tissue damage in the lungs. This modulation of the immune response could synergize with the effects of oseltamivir in regulating neutrophil activity, further enhancing its efficacy in vaccinated individuals.

In summary, while oseltamivir’s traditional mechanism of action targets viral neuraminidase, emerging research suggests that its efficacy in COVID-19 patients may involve modulation of the neutrophil response. This alternative pathway provides new insights into the potential mechanisms underlying oseltamivir’s action in COVID-19 and offers a rationale for its observed benefits, particularly in vaccinated individuals. However, further research is needed to fully elucidate the intricacies of oseltamivir’s mechanism of action in the context of COVID-19 and to explore its therapeutic potential in clinical practice.


Oseltamivir’s Effectiveness in Reducing COVID-19 Mortality: Analyzing Nationwide Hospital Data

A recent study utilizing nationwide hospital data has shed light on the potential effectiveness of oseltamivir in reducing COVID-19-related mortality. The study conducted subgroup analyses that revealed varying levels of effectiveness based on vaccination status, with vaccinated individuals experiencing additional benefits from oseltamivir. This article delves into the details of the study, its methodology, findings, underlying mechanisms, limitations, and implications.

Existing studies on the effectiveness of oseltamivir in COVID-19 patients have been limited and yielded contradictory results. Some studies failed to control for important confounders such as comorbidities, raising questions about their validity. Additionally, retrospective cohort studies from Iran and Saudi Arabia reported mixed results, possibly due to small sample sizes.

The highlighted study addressed these limitations by controlling for confounders and assessing possible unmeasured confounders. Case inclusion criteria aimed to mitigate unmeasured confounders at various levels, enhancing the robustness of the analysis. The study’s findings suggested a significant association between oseltamivir and reduced mortality, particularly in individuals previously vaccinated against SARS-CoV-2.

The mechanism of oseltamivir in COVID-19 patients has been a subject of interest, considering its original development for influenza treatment. While oseltamivir targets viral neuraminidase in influenza, its efficacy against SARS-CoV-2 was initially doubted due to the virus’s lack of neuraminidase. However, recent research proposed a potential pathway for oseltamivir’s action in COVID-19 by regulating neutrophil response, thereby reducing disease severity. This mechanism could also explain the additional benefits observed in vaccinated individuals, possibly due to a weakened neutrophil response in those with prior vaccination.

Despite the positive findings, the study acknowledged several limitations. These included potential biases from self-reported symptoms, selection bias from missing data, and the absence of laboratory data indicating disease severity. Additionally, the study lacked information on the specific dosage of oseltamivir administered, highlighting a need for further research to elucidate optimal dosing regimens.

Furthermore, the study emphasized the importance of ongoing research to assess oseltamivir’s effectiveness in different phases of the pandemic, particularly in the post-Delta period. Additionally, the study acknowledged reported adverse reactions to oseltamivir, such as nausea and vomiting, as well as potential interactions with other medications.

In conclusion, the study provides valuable insights into the potential role of oseltamivir in reducing COVID-19-related mortality, especially in vaccinated individuals. However, further research is warranted to validate these findings, address limitations, and optimize treatment strategies for COVID-19 patients.

reference link :

  • https://www.drugs.com/medical-answers/tamiflu-work-covid-19-3537049/
  • https://www.sciencedirect.com/science/article/pii/S0924857924000293
  • https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0277206


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