Main Info | Symptoms | Treatment | H5N1

Medication Available

Antiviral drugs are currently the most effective forms of vaccination and treatment against avian influenza in human victims. They obstruct the virus from replicating within a victim and thus hinder the severity of infection, curtailing the duration of symptoms and offering a degree of prevention against bird flu.



Currently, there are four antiviral drugs on the market targeted at avian influenza treatment, including amantadine, rimantadine, oseltamivir (better known as Tamiflu®) and zanamivir (more commonly known as Relenza®). The former two however, are ineffective against the infamous H5N1 subtype, presently the greatest cause of concern, (See Threat) but are adequate treatments against the less virulent forms of bird flu viruses. Tamiflu and Relenza are currently the only two drugs useful against H5N1.

Tamiflu® and Relenza®

These are the two primary antiviral drugs that can effectively treat human bird flu infection, including H5N1, if taken within the initial 48-hours of symptom emergence.

The first antiviral drug, Tamiflu®, comes in the form of a tablet or bottled syrup that may be ingested like everyday flu medicines. Relenza® is the second and comes in a powdered form, which must be inhaled in a certain manner through the mouth or nose, making it less convenient/ user-friendly. Both are classified as neuraminidase inhibitors, separating them from the M2 inhibitors that are amantadine and rimantadine.

Global sales of Tamiflu® early in 2005 expectedly skyrocketed following the worldwide alarm at the possibility of a bird flu pandemic.

Effectiveness of Treatment

There is no definite cure for avian influenza as of this moment. Antiviral drugs do deter the severity of disease onset but only if consumed within the first 48 hours and effectiveness is of course, also dependent on the individual victim. On average, the disease duration is reduced by 1-2 days through the use of antiviral drugs and the odds of developing pneumonia are also reduced (not prevented) by 40-50%. During drug use, there is an added 80-90% level of bird flu immunity in the patient which is effective so long as the medication is taken.

Age Limitations

Tamiflu® is permitted for the treatment of bird flu in all patients above 1 years of age while Relenza® may only be consumed by individuals of 7 years or above. Relenza® is prohibited for the use of resistance boosting though Tamiflu® may be consumed to help prevent bird flu in persons no younger than 13 years of age.

Antibiotics

Antibiotics are ineffective against life threatening forms of pneumonia in cases of human H5N1 infection. However, should signs of pneumonia arise late, antibiotics prove useful in treating secondary bacterial lung infections in bird flu patients. They cannot fight symptoms caused by the actual virus.

Resistance to Drugs

Bird flu viruses are capable of acquiring resistance to antiviral drugs, as was discovered by the mass injections of amantadine into chicken flocks during the late 1990s in China. Secretly done in an attempt to thwart an outbreak of avian flu, around 2.6 million injections of amantadine were distributed among the nation’s poultry. Certain strains of the avian influenza viruses in Asia have since been discovered resistant to the drugs amantadine as well as rimantadine, both being M2 inhibitors.

A unique case of human H5N1 infection in Vietnam also demonstrated that the virus could potentially become resistant to Tamiflu®, currently the leading antiviral drug against bird flu. A 14-year-old Vietnamese girl was believed to have contracted H5N1 from her older brother, who had been infected with the virus earlier on. While taking care of him, the girl became infected with avian influenza despite consuming Tamiflu® three days prior to the first signs of illness. Samples of the virus taken from the girl showed that several strains of the H5N1 had mutated to evade the function of the drug. This was also an unusual case of human-to-human transmission and has confirmed fears of a wide-scale mutation which could lead to sustained human bird flu infection. However, there have been no other such cases documented to date.

Setbacks

By far the greatest drawback of antiviral drugs effective against H5N1 is the cost and duration of drug production. Tamiflu is undoubtedly the number one demand on the market, boasting an order list with countries like the UK, Hong Kong, Singapore, Thailand and the US. The drug is expensive, but deemed a necessity by leading economists across the globe considering the potential economical consequences of a pandemic. (See Threat)

The lack of Tamiflu stock in the United States is particularly serious considering its position as a major backbone to the global economy - only 1% of the US population is expected to be covered under the current Tamiflu stock in America. Meanwhile, it’s been estimated that the time required to produce sufficient Tamiflu for just one fifth of the world’s current population would require a period 10 years based on the present production rate of the Swiss drug firm, Roche. It’s not simply a matter of money that can resolve the Tamiflu shortage, but additionally, time.