The world's only known working anti-viral flu drug Tamiflu has been rendered ineffective against the bird-flu strain H7N9 virus. Essentially, the virus has mutated. It won't be long before global pandemonium erupts unless a new effective drug is created and immediately made available to humans.

In a research that involved 14 patients published on Tuesday in the British Lancet medical journal, it was found that the flu drug was ineffective in three patients.

In fact, researchers even theorised the gene mutation developed as a result of treatment with Tamiflu. Given as a pill, Tamiflu belongs to a group of medicines known as neuraminidase inhibitors. Manufactured by Roche, it is the only known treatment option for bird flu.

Read: H7N9 Virus: Human-to-Human Transmission Possible - Study

Researchers saw the resistance take hold in one patient after initial infection. The virus, while infecting the patient's body, adapted to the treatment with the drug. After nine days of treatment with Tamiflu, the virus developed a mutation in the neuraminidase gene, the N in H7N9, thus making the drug ineffective.

"The apparent ease with which antiviral resistance emerges in A/H7N9 viruses is concerning; it needs to be closely monitored and considered in future pandemic response plans," the researchers wrote.

Although Tamiflu successfully reduced the amount of virus found in the throat swabs for most of the 14 patients studied and helped speed their clinical recovery, the anti-viral flu drug however had no impact on the amount of virus found in swabs from the three patients who became severely ill.

"Rates of Tamiflu resistance remain low globally although Roche takes the issue of resistance very seriously and collaborates with international organizations and authorities to monitor the situation," the company said in a statement released on Tuesday.

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