JULY 4, 2007
 (STAR) By Sheila Crisostomo - Many vaccine manufacturers are interested in producing pre-pandemic vaccines against human influenza but they cannot do so in large volume because the virus that will actually cause such a pandemic remains unknown, the World Health Organization (WHO) said.

Dr. Takeshi Kasai, WHO regional adviser on communicable diseases’ surveillance and response for Western Pacific, said many manufacturers have already produced such vaccines but in limited quantities.

“Many manufacturers are very interested but I think the size, the production for pre-pandemic (vaccindes) is not to that extent. They are not ready to produce in huge (quantities)… because we never know what’s the responsible strain that will cause the pandemic,” he said in an interview during an Outbreak Communication Training and Workshop here.

The vaccines were developed using Clade 1 and 2, the most common strains of the H5N1 virus found among those afflicted with human influenza.

Manufacturers are expected to produce the vaccines only when a pandemic-causing virus is known and when a pandemic is forthcoming. It usually takes three to four months to produce a vaccine, depending on the production methods.

A WHO fact sheet shows that H5N1 is a virus that causes avian influenza. But just like other viruses, the H5NI is feared to change in form and “ultimately adopt into a strain that is contagious among humans.”

“Once this adaptation occurs, it will no longer be a bird virus — it will be a human influenza virus. Influenza pandemics are caused by new influenza viruses that have adopted to humans,” the fact sheet states.

But Kasai maintained that for avian influenza to become human “is not that easy but that does not necessarily mean that a pandemic will not occur.”

Since January 2003, the WHO has registered 312 cases of laboratory-confirmed human influenza. The patients got the infection either because of their very close exposure to infected chicken or sick humans, hence the human-to-human transmission of the virus is still considered limited.

Kasai said it is important for all governments to be on guard against avian and human influenza.

WHO records show that three cases of human pandemic influenza occurred in the previous century — the “Spanish influenza” in 1918, the “Asian influenza” in 1957, and the “Hong Kong influenza” in 1968.

The 1918 pandemic killed some 40 million to 50 million people worldwide, making it one of the deadly disease events in human history. The 1957 and 1968 pandemics caused two million and one million deaths, respectively.

Kasai said infectious diseases emerge because of poverty, continuing population growth and urbanization, expanding areas of human habitation, migration and mass movement, increased international air travel and trade, weak public health infrastructure, climatic change, and deforestation, among other factors.

By cultivating lands, Kasai said humans also have a greater chance of encountering “zooneses” or diseases of animals found in nature.

“Globally, (there is) an average of one newly emerging disease each year in the past three decades, more than 70 percent of which were so-called zoonoses… Infectious diseases remain as the world’s leading cause of death, accounting for at least 17 million (about 33 percent) of the 52 million people who die each year,” he said.

Although the Philippines remains free from avian influenza and human influenza, Kasai said it should observe precautionary measures.

“The preparedness of countries that experienced bird flu like Vietnam, Cambodia and Laos has become stronger and stronger. (The) Philippines has not exercised readiness. One thing which we recommend is that they do their own exercise… Countries need to prepare for containment activities,” he said.

Chief News Editor: Sol Jose Vanzi

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