Heavily Prescribed Influenza Medicine Doesn’t Work Well, Study Finds

A package of Tamiflu in a file image. Mario Tama/Getty Images

One of the most-used influenza medicines doesn’t work well in preventing severe complications that lead to hospitalization, according to a new study.

Dr. Emily McDonald and other Canadian researchers reviewed data from 15 randomized clinical trials, including eight that were conducted by the drugmaker Roche but not published. They analyzed whether the drug oseltamivir, known as Tamiflu, was associated with lower hospital admissions among outpatients infected with influenza.

While some of the trials were favorable for Tamiflu, others were not. Many showed little to no effect either way. Few people overall were hospitalized in the studies, including participants who did not receive Tamiflu.

The meta-analysis primarily studied the number of admissions, for any cause and direction, to a hospital or health care center.

The researchers also examined the occurrence of adverse events and discovered that people who received the drug faced significantly more cases of nausea, vomiting, and gastrointestinal disorders, though they also experienced a lower risk of diarrhea. Nausea, vomiting, and headache are listed as side effects on labels of the drug.

“The harms of taking the medication outweigh the benefits for most patients,” McDonald, with the McGill University Health Centre Division of Infectious Diseases and Centre for Outcomes Research and Evaluation, told The Epoch Times in an email.

“I would not prescribe Tamiflu to a healthy outpatient population based on the study findings. Even among high-risk patients, the effect is not yet proven, and if there is any effect, it will be very small,” she added.

McDonald would still prescribe Tamiflu to populations at very high risk, such as people with leukemia or lymphoma.

Dr. Adam Urato, a doctor in New Jersey, said on Twitter that the study’s findings “should be the nail in the coffin for Tamiflu” while Dr. Adam Urato, a doctor in Massachusetts, said that the public is told drugs are safe and effective but “often this turns out to be false,” naming Tamiflu and Vioxx as examples.

The research was published by JAMA Internal Medicine on June 12.

Tamiflu Background

The U.S. Food and Drug Administration (FDA) approved Tamiflu in 1999 as a treatment for adults with influenza. It has since been expanded as a treatment for infants as young as two weeks old within two days of symptoms appearing and as a preventative drug for people 1 and older. Japanese and European regulators soon followed the United States. Additional countries, such as Canada, later cleared the drug.

Most of the studies that prompted the clearances were funded by Roche, which manufactures the drug. The primary trial showed that people treated with Tamiflu resulted in a shorter duration of illness, the FDA said.

Treatment can be initiated within 48 hours of symptom onset, according to the FDA. The U.S. Centers for Disease Control and Prevention recommends people receive antiviral drugs like Tamiflu if they have suspected and confirmed influenza and are hospitalized, have severe illness, or are at higher risk for complications.

About 2.8 million patients received Tamiflu in 2020 in the United States, which along with other countries has stockpiled the drug in case the supply runs low.

McDonald and her colleagues noted that studies have reported a lessening of symptom duration. “Whether this decrease is meaningful when compared with medication costs, an increase in nonsevere adverse events, and the opportunity cost of missing out on the discovery of more effective therapies is a topic of study for health care economists and could be discussed on an individual patient basis,” they wrote.

Previous Meta-Analyses

A 2003 Roche-funded meta-analysis concluded that the treatment reduced complications and hospitalization in adults, including healthy adults.

A meta-analysis in 2014 that included, for the first time, unreported data from the early trials concluded that Tamiflu does reduce symptom duration but there was no effect on hospitalization. The review also found a number of side effects, including an increased risk of nausea and vomiting.

“The trade-off between benefits and harms should be borne in mind when making decisions to use oseltamivir for treatment, prophylaxis, or stockpiling,” the authors said at the time.

A year later, another meta-analysis found that the drug reduced symptom duration and hospital admission, though it also found an increase in nausea and vomiting.

Some of the Roche-funded trials were included in the new meta-analysis, as were four trials that reported results that had not been included in previous meta-analyses.

One that ended in 2017 found that Tamiflu decreased viral shedding but did not significantly affect symptom duration. One that ended in 2016 found a newer treatment called baloxavir marboxil was superior to Tamiflu. One that ended in 2018 found that Tamiflu led to shorter symptom duration but an increase in vomiting and nausea. The fourth found that baloxavir marboxil produced similar results as oseltamivir.

Given the uncertainty surrounding Tamiflu’s risk-benefit profile, the Canadian researchers recommend future trials in high-risk populations. “A large adequately powered trial would be possible for researchers,” McDonald said, pointing to the RECOVERY trial in the United Kingdom for COVID-19 drugs. “It does not have to be an industry trial.”