Scientists around the world have been feverishly searching for ways to effectively combat the influenza virus since the causative microbe was first identified 100 years ago.
We currently rely on hit-and-miss vaccines or questionably effective antiviral medications such as Tamiflu (oseltamivir). Neither option can protect against or adequately treat all strains of the quickly mutating virus, leaving the public vulnerable to seasonal pandemics such as the 2009 swine flu one.
Development of a “universal” flu vaccine that protects regardless of seasonal variation is currently underway, yet it may take years for a product to reach the public. And even if it does, it only primes the immune system for attack by subtype A viruses, leaving the other large B family out entirely.
The tide may soon turn in our favor, however, thanks to breakthrough antiviral research in Japan that has culminated in the development of a new medication reported to eliminate flu infections within one day.
According to the Wall Street Journal, the drug, called baloxavir marboxil, could be available in Japan as soon as May of this year following the success of a phase 3 clinical trial that evaluated its safety and efficacy in 1,436 Japanese and American flu patients.
Unfortunately, the promising treatment is unlikely to be approved in the US before 2019.
Developed by Osaka-based pharmaceutical company Shionogi, baloxavir marboxil works by inhibiting an enzyme, called cap-dependent endonuclease, that is essential to the process by which the influenza virus translates its genes into proteins. By blocking all viral gene expression, baloxavir marboxil theoretically prevents not only the spread of replicated virus particles (as Tamiflu does by targeting neuraminidase) but also circumvents the virus’ ability to enter our cells, and thus induce symptoms, in the first place.
Otherwise healthy study subjects who had begun showing signs of infection within the last 48 hours experienced symptom relief 53.7 hours after taking just one pill of baloxavir marboxil. People who received a placebo pill had to wait 80.2 hours for improvement.
Viral shedding – an indicator of freshly reproduced virus particles in the tissue – was completely stopped after a median of 24 hours. In patients who took a standard course of Tamiflu (two pills a day for 5 days), viral shedding continued until 72 hours after the first pill, and placebo pill patients showed signs of active infection for 96 hours.
Furthermore, the trial suggests that baloxavir marboxil causes fewer side effects than Tamiflu, a treatment option sometimes avoided simply because the list of possible bad reactions is long (and scary).
Despite its promise, it must be noted that the drug comes with several potential limitations. Because the study excluded people at high risk of developing flu complications and those who already displayed signs of them, it remains unknown how well the new option will work in severe cases. Considering that the actual cause of death from influenza is almost always a fast-moving secondary bacterial infection, this information will be critical for determinating the drug’s range of application.