This year’s flu season has killed more than 100 children, and led to more than 1,100 hospitalizations per week — a rate the U.S. has not seen in more than 15 years.
When the flu strikes, many rush to the doctor for Tamiflu, a popular drug approved to treat influenza’s basic symptoms and keep the virus from multiplying in the body. But doctors also prescribe the drug to tackle or prevent the flu’s life-threatening complications, like pneumonia and asthma attacks.
NewsHour asked a drug safety researcher, a virologist at a children’s hospital and a medical officer at Centers for Disease Control and Prevention whether Tamiflu delivers on these claims.
What does Tamiflu do?
Tamiflu is an antiviral drug that blocks an enzyme called neuraminidase, which helps the flu virus replicate and spread through your body. Most flu researchers agree on the basics — that Tamiflu will reduce symptoms, like stuffy nose, sore throat, fever and tiredness, which is something many over-the-counter medications do too.
“The ideal scenarios is to start [Tamiflu] treatment as soon as possible,” said Dr. Elena Govorkova, laboratory director in the division of virology at St. Jude Children’s Research Hospital in Memphis, Tenn. “The most efficacy is received when treatment starts within 48 hours after symptoms start to appear.”
Govorkova said Tamiflu is clinically proven to reduce the duration of influenza symptoms by one to two days, which may not seem like much. “But when you have thousands people infected, especially if people are working, it makes, of course, a huge impact,” Govorkova said.
But broader claims about Tamiflu’s effectiveness made by the Centers for Disease Control and Prevention conflict with those of the U.S. Food and Drug Administration, according to drug safety researcher Peter Doshi at the University of Maryland School of Pharmacy.
The CDC describes Tamiflu as a drug that may “reduce the risk of complications such as ear infections in children, and pneumonia and hospitalizations in adults.” The FDA’s drug label for Tamiflu, however, says the remedy “has not been shown to prevent such complications.”
Doshi, who supports the FDA’s position, said this difference of view is a public health concern.
But Tim Uyeki, chief medical officer for the CDC’s influenza division, disagrees with the FDA’s narrow definition. He said the two agencies are acting according to their respective missions. Whereas the FDA approves drugs based on strict “controlled trials,” Uyeki said, the CDC is not a regulatory authority.
Instead, the CDC makes recommendations for public health based on a broader, albeit less strict, body of evidence, Uyeki said. For example, it gathers “observational data,” such as years of notes on flu patients who walk into hospitals seeking treatment.
Based on this observational data, Uyeki said that oseltamivir — the generic name for antivirals that include Tamiflu — can improve survival against the worst flu complications, especially when the drug is compared to no treatment at all.
Reviewing the evidence
But Doshi said the leap from ‘reducing symptoms’ to ‘preventing complications’ is a stretch. When asked if Tamiflu provides additional benefits against the worst of the flu, Doshi said, “That’s where the evidence gets very dicey very quickly.”
In 2009, Doshi’s team got a tip from a pediatrician that the data for the Tamiflu clinical trials were not publicly accessible. This pediatrician noticed the claims on Tamiflu’s effectiveness were based on manufacturer-funded studies. That discovery prompted Doshi’s three-year effort to obtain and analyze the studies behind Tamiflu’s FDA approval.
Doshi’s team concluded in a 2014 Cochrane review article that the clinical trial data did not support the broader claims made about Tamiflu. The team looked at clinical study reports for 83 trials and found no improvement for admission-to-hospital rates, pneumonia or bronchitis. However, they did see a more than 50 percent reduction in influenza symptoms.
Uyeki said Doshi’s review has had a tremendous influence because of the worldwide reach of Cochrane, but added that the results are misleading.
Uyeki called Doshi’s evidence “watered down” because it relied on patients who had influenza-like symptoms, but were not necessarily confirmed by laboratory testing to have the flu. Many different viral infections and some bacterial infections can mimic “flu-like” symptoms. So if one patient received Tamiflu and did not have the flu, then he or she may have skewed Doshi’s data, Uyeki said.
The Cochrane review focused on “influenza-like” illness as an outcome because that’s “the thing people want to avoid,” Doshi said, adding that the outcomes with pneumonia and hospitalizations are the same, regardless of whether you’re looking at flu-like cases or lab-confirmed cases.
Govorkova said that Tamiflu can reduce the chances of catching pneumonia.
She explains: Pneumonia is caused by bacteria, not the influenza virus. But the flu virus, in some cases, can predispose receptors on the epithelial cells lining our throats and lungs to become infected with pneumonia-causing bacteria.
“[Tamiflu] is not for the treatment of pneumonia — you must use antibiotics,” Govorkova said. “But because [Tamiflu] is very specific for influenza virus, if you start early, you can eliminate influenza virus from the body. And because of that, pneumonia cannot occur.”
Doctors may also prescribe Tamiflu in cases, she said, when another remedy isn’t available — such as during avian H5N1 influenza outbreaks. “Vaccines were not available for prevention purposes, so they were giving Tamiflu even after 48 hours of exposure,” Govorkova said.
Why this debate matters
Doshi and Uyeki do agree that underlying chronic conditions — like asthma, obesity, diabetes and heart disease —
But with the flood of alarming media and rising flu-related hospitalizations, Doshi worries people will begin to count on Tamiflu to save lives. He said viral stories, such as those about a Texas teacher or a New Hampshire mother, that link their flu-related deaths to refusing Tamiflu, lead people to believe Tamiflu is a “wonder drug” that could help the situation in the first place.
“[Those stories] project this sense that we’re certain that if only she had taken Tamiflu she would be alive today, and we don’t have any evidence to know that that’s the case,” Doshi said. “So it really spreads a dangerous message.
Govorkova said patients should consult their doctors on whether Tamiflu could be helpful. They should also make sure to take the full course of medicine.
Some people drop out early or take it once a day rather than twice a day, she said, and this should be avoided because it can cause the emergence of Tamiflu-resistant flu strains.