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Tamiflu For Preventing Flu Admissions - Or Not

Influenza, or the "flu," is a viral respiratory infection that commonly affects the nose, throat, and lungs. Some symptoms of flu infection include fever, muscle ache, headache, dry cough, shortness of breath, general malaise, and more. Most healthy people with active flu infections can fight off the infection with their immune systems, however, certain high-risk groups may be prone to developing complications, such as children under 2 years old, adults over 65 years old, those that are pregnant, those with weakened immune systems, those with chronic illnesses, and those with a body mass index of 40 or higher. 

The influenza vaccine is a preventative vaccine that reduces the chances of a patient having severe complications from the virus. Even after preventative measures such as the influenza vaccine, some adults remain at high risk for hospitalization following an infection. That is where flu antiviral drugs come in; antiviral drugs are medications that assist your body in fighting viruses. 

The most common antiviral for the flu is Tamiflu, generically known as oseltamivir. Oseltamivir is a neuraminidase inhibitor and was approved by the United States Food and Drug Administration in 1999. When oseltamivir is started within two days of flu symptoms and confirmed flu infection, it can shorten length of illness along with a decrease in overall symptoms. This is especially useful in high-risk populations who may be able to prevent a hospitalization after taking oseltamivir.

However, there is considerable emerging data about the actual efficacy of oseltamivir. One study published in the Indian Journal of Pharmacology in 2015 notes issues raised by the Cochrane Team that claims the randomized controlled trials were not precise, nor did they have high-quality data. They claim that these trials were poorly designed. 

More recently, a study released in the Journal of the American Medical Association in 2023, showed that oseltamivir was not associated with a reduced risk of hospitalization for the infected population, and was not associated with a reduced incidence of hospitalization in older populations or in patients at greater risk. Unfortunately, on the other hand, it was associated with increased nausea and vomiting in patients taking it. 

Emily McDonald, MD, MSc, the Principal Investigator in this trial and a medical doctor, said in an interview with MedPage Today that she "wouldn't prescribe it to an otherwise healthy person." Additionally, she argues that current treatment guidelines for oseltamivir need to be reviewed, stating that overprescribing is a big problem especially when it comes to antibiotic medications and antiviral medications. 

While antiviral medications like oseltamivir (Tamiflu) have been widely used as a treatment option, recent studies have raised questions about their true effectiveness and potential side effects. As further research and analysis continue, it is essential for healthcare professionals to carefully evaluate the benefits and risks of antiviral treatments for each patient, ensuring appropriate and informed decision-making.

Sources: Mayo Clinic, CDC, Indian Journal of Pharmacology, Journal of the American Medical Association, MedPage Today

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CDC Raises Risk Slightly For Recent H5N1 Avian Flu Viruses

The Centers for Disease Control and Prevention (CDC) this week published a new risk assessment for the H5N1 avian flu viruses that continues to circulate in wild birds and poultry, using a sample from a 2022 outbreak at a Spanish mink farm. Though the virus scored higher on some risk measures, the overall threat is moderate and similar to the earlier version of the virus.

Scientists said human infections remain rare and the likelihood of human-to-human transmission remains low.

Risk similar for both viruses

The CDC conducted the assessment using the Influenza Risk Assessment Tool (IRAT), which has a goal of answering two questions, one on emergence and the other on public health impact. Health officials use IRAT to gauge the pandemic potential of flu viruses and to guide preparedness measures.

The outbreak at the mink farm occurred in October 2022, raising concerns about whether the virus had gained the potential to spread more easily between mammals.

The CDC conducted its last analysis of the virus in March 2022 using a sample from a wigeon duck collected in South Carolina in 2021 when the virus first began circulating in US wild birds. The group's new assessment—done in April—covers new information since then, including eight more human cases, some of which were severe.

CDC reviewers rate the virus on 10 risk elements, which range from antiviral treatment options to transmission in animal models.

The risk score for potential emergence of the newer virus was 5.13, reflecting an increase of 0.69 and putting it in the mid-low part of the moderate range. On the public health impact question, CDC officials gave it a risk score of 6.24, an increase of 1.17, putting it in the middle range of the moderate-risk category.

Though the newer virus scored higher on both measures, the CDC emphasized that the ranges for the mean high and the mean low acceptable scores for both viruses overlap, meaning that they remain similar.

The newer virus from the minks scored higher than the earlier duck virus on 6 of the 10 risk elements, which included antiviral treatment options, disease severity and pathogenesis, genomic analysis, human infections, infections in animals, and transmission in animal models.

Genetic analysis also finds similarities

Phylogenetic analysis suggests the clade 2.3.4.4b viruses are similar to previously circulating viruses from the same clade, with little evidence of adaptation to mammals. Also, the hemagglutinin gene of current viruses are highly similar to previous viruses, with some variation in the neuraminidase gene, which the CDC said is adapted to wild birds.

The agency said previously recommended candidate vaccine viruses against H5 are expected to be effective against the H5N1 viruses circulating in birds and poultry, and most viruses remain susceptible to antiviral medications.

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