Before his recent untimely death while on his way to an international conference on influenza pandemic preparedness, renowned virologist Graeme Laver told HSToday.us during many lengthy interviews that pandemic preparedness authorities needed to begin stockpiling all flu antivirals in the event that one or more strains – in particular especially virulent strains - of influenza begin to show marked resistance to existing antivirals. As HSToday.us has reported, resistance to Tamiflu in particular has been growing among some strains, including H5N1 and seasonal influenza strains.

There have been growing concerns on the part of virologists for some time that antiviral resistant influenza could be a serious problem during a pandemic, as antivirals will be the primary defense against a pandemic until an effective vaccine is developed. Tamiflu has been stockpiled in the US and many other nations because of its effectiveness in diminishing the ravaging effects of virulent influenza strains.

But because of evidence of growing resistance, British researchers warned a year ago that governments need to stockpile antivirals besides just Tamiflu in the event that a mutated pandemic strain of H5N1 is resistant to Tamiflu.

"Studies with HIV, leukemia have shown that we have to use multiple drugs," virologist Robert Webster at St Jude Children's Hospital stated at a recent medical conference in Hong Kong. He suggested that oseltamivir and zanamivir be used along with other antivirals like ribavirin, amantadine and rimantadine.

According to a new study, Morbidity and Mortality Associated With Nosocomial Transmission of Oseltamivir-Resistant Influenza A(H1N1) Virus, published in the March 2 Journal of the American Medical Association (JAMA), and authorities at the Centers for Disease Control and Prevention (CDC), a natural genetic mutation in A(H1N1) influenza rather than the virus’s adaptation to survive treatment with antivirals, has made it resistant to Tamilfu (oseltamivir). And this poses an extraordinarily serious health threat to patients hospitalized with the flu virus being treated with this antiviral.

While Tamiflu-resistant influenza increasingly has been found around the world since January 2008, it had been presumed that strains carrying the mutation were of lower risk and less likely to be transmitted. "However, current widespread circulation of oseltamivir-resistant influenza A(H1N1) viruses associated with typical influenza illnesses and viral pneumonia suggest that these viruses retain significant transmissibility and pathogenicity," the authors of the new JAMA report wrote.

CDC officials stated that nearly all cases of the most common seasonal flu strain in the United States is resistant to Tamiflu.

"As of February 19, 2009, resistance to oseltamivir had been identified among 264 of 268 (98.5 percent) U.S. influenza A(H1N1) viruses tested,” the researchers noted.

"We have been extremely foolish on our policies of stockpiling drugs. We have been stockpiling two varieties of the same drug," Webster stated, later telling reporters that “the likely scenario is that the (H5N1) virus will become resistant when you start using more and more [of one] drug, you get resistant (H5N1) mutants.”

Tamiflu and the other widely administered antiviral, Relenza, are similar.

H5N1, of course, is the most virulent strain of influenza in the world today and the strain virologists have worried will cause a pandemic. Should a pandemic strain of H5N1 also be resistant to antivirals, efforts to combat it will be gravely compromised and many more people inevitably will die and be sickened. Unless other effective antivirals are developed, a vaccine will be the only hope of combating the virus.

"It does show that we have to take the risks of a Tamiflu resistant pandemic more seriously," Anders Tegnel at the Swedish National Board of Health and Welfare, told the Swedish English newspaper, The Local.