BANGKOK, Thailand - A day after Thai and international officials confirmed the first probable human-to-human transmission of a virulent strain of avian influenza in this country, public health systems around the globe were scrambling to prepare for a possible pandemic.
Scientists say they cannot predict how quickly, if at all, the strain might develop the ability to spread easily among people, and whether it will remain as lethal as it has proven. The strain, A(H5N1), has killed 30 of the 42 Southeast Asians it infected in the past year, as well as millions of chickens and wild birds, across wide areas of Asia, and it has infected pigs, household cats and even zoo tigers. A handful of cases of human-to-human transmission might have occurred during bird flu outbreaks in Hong Kong in 1997 and in Europe a year ago, but neither resulted in a pandemic.
Nevertheless, public health experts say it would be irresponsible not to prepare for a worst-case scenario. The so-called Spanish Flu pandemic of 1918 to 1919 - believed, like the current strain, to have been a mutant virus that jumped from animals - killed an estimated 20 million to 100 million people, and that was before the development of the modern transportation system, with its fleets of jets linking remote areas of the world. By comparison, AIDS has killed an estimated 22 million since 1981, according to the United Nations.
Yesterday, the World Health Organization held a meeting in Geneva of representatives of the drug industry to demand that they speed vaccine production. In the United States, scientists with the federal Centers for Disease Control and Prevention in Atlanta are racing to complete a genetic sequence of the virus from this case to determine if it has acquired any mammalian influenza genetic material, which could make it more transmissible, and the government has ordered 2 million doses of experimental vaccine.
Health officials would normally look to vaccines and antiviral drugs to control a pandemic, but in this case those tools have yet to be fully developed and tested. Conventional flu vaccines are not believed to provide any protection against A(H5N1) avian influenza. Human trials of the new vaccine ordered by the U.S. government are not due to begin until the end of this year, at the earliest.
The United States, like governments in Australia, Japan, New Zealand and a small number of other countries, is also stockpiling the only antiviral medicine that might work against the strain, Tamiflu, but there have been too few human cases to document its effectiveness. The symptoms of human bird flu appear to be indistinguishable from severe cases of conventional flu, with fevers, sneezing, coughing and aches.
Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases, said that the U.S. government is "doing everything that is ... feasible to be done at this time - essentially, loading up and stockpiling Tamiflu to the extent of almost exhausting the manufacturer's capabilities."
But the absence of a tested vaccine and the scarcity of the antiviral underline what many health officials say is a chronic mismatch of public health needs and private control of production of vaccines and drugs. "The market has failed here to drive companies into research, and we believe that's something public health should be looking at much more closely in the future," said Klaus Stoehr, the WHO's top influenza expert, before the meeting yesterday.
Only two large vaccine manufacturers, Aventis Pasteur Inc. of Swiftwater, Pa., and the Chiron Corp. of Emeryville, Calif., are braving a thicket of patent issues and financial feasibility concerns to try to use advanced genetic techniques to develop vaccines against so-called bird flu. They have proceeded only with National Institute of Health contracts to do so.
Other drug makers have given reasons for not making their own vaccines: that production is expensive and investment might not be recouped if there is no pandemic, and that intellectual property rights concerning new techniques used to make the vaccine are unsettled. The standard technique for making flu vaccines - growing virus in chicken embryos - does not work because the A(H5N1) virus is so deadly it kills the developing chicks before they can grow enough virus to be worth harvesting. The new techniques alter the strain's genetics so it can be grown in the fertilized eggs.