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Thursday, June 11, 2009
Vaccine strategy poses serious quandary
Focusing on new virus would cut output for seasonal influenza
The swine flu panic has waned in the past few weeks and authorities are breathing a sigh of relief, but some medical experts say the government has been slow to prepare for a possible second outbreak this fall.
Their chief worry is whether there will be enough vaccine.
"We should shift to manufacturing vaccine for swine flu" rather than seasonal flu, said Norio Sugaya, an infectious disease expert and head of pediatrics at Keiyu Hospital in Kanagawa Prefecture.
While symptoms of the new H1N1 virus have turned out to be mild, it spreads fast, as evidenced by the more than 500 cases reported in Japan since May 9.
Taking into consideration the 27 flu-related deaths as of Monday in the United States, Sugaya said the central government should concentrate on building up supplies of the vaccine for swine flu instead of seasonal influenza.
"In the U.S., around 9 percent of swine flu patients are hospitalized and 20 percent to 30 percent of (the 9 percent) are sent" to intensive care units, he said.
Sugaya noted that the World Health Organization may soon declare a Phase 6 outbreak — meaning a global pandemic — as the H1N1 virus spreads in the Southern Hemisphere, including Australia, where more than 1,000 people are infected.
It's a turnaround for Sugaya, who originally counseled that the government shouldn't disregard seasonal flu.
According to the Japanese Association for Infectious Diseases, around 10,000 people die in Japan from seasonal flu every year.
When health minister Yoichi Masuzoe said in April the government should focus on producing the vaccine for swine flu, Nobuhiko Okabe, director of the Infectious Surveillance Center, also said there has to be a compelling reason to manufacture vaccine only for the H1N1 strain.
So far, the Health, Labor and Welfare Ministry estimates that enough swine flu vaccine for 25 million people can be prepared. However, a ministry official on the H1N1 task force said they "will make a decision after the WHO releases a public statement on swine flu vaccination," expected next month.
Because both types of vaccine have a two-week lag before taking effect, experts say inoculations should be under way by mid-November before the viruses start to spread.
However, production of the seasonal flu vaccine, accomplished by cultivating the virus in eggs — the only method permitted in Japan — usually takes about six months, which means the swine flu vaccine made by the same procedure might not be ready by November.
The ministry official said "it is not confirmed when the swine flu vaccination can be offered." With drugmakers now testing how fast they can make the swine flu vaccine, the production schedule cannot be confirmed until those results come out, she said.
These problems can be solved, hopefully by 2011, if the government allows mass production of both vaccines from cells instead of eggs. This would shorten the production period to eight weeks, or a third of the current method, according to Masanori Yoshida, manager of business planning at UMN Pharma Inc.
The firm, using technology it obtained from Protein Sciences Corp. of the U.S., is conducting clinical tests on a vaccine for the H5N1 bird flu, which is expected to hit the market in three years.
The major difference between the existing method and the new technology, called the Baculovirus Expression Vector System, is that the former cultivates the virus while the latter cultivates hemagglutinin — a core ingredient of the vaccine.
In the new method, the firm produces a gene that makes hemagglutinin, a substance found on the surface of the influenza virus.
The only requirement is information on a virus gene, therefore the virus itself is not necessary, Yoshida said. The gene is cultivated in a cell obtained from a moth, and the hemagglutinin that is produced from the gene is refined into the vaccine.
"There is a limit on how much vaccine output can be increased if we make vaccine through eggs, because you cannot suddenly increase the number of eggs when needed," Yoshida said.
"But (the cell cultivation) only requires more factories."
The BEVS method will not be used to manufacture the H1N1 vaccine because the firm has not conducted the clinical testing needed and does not have a facility to mass produce it, he said.
In addition to vaccine production, Sugaya of Keiyu Hospital said the government should also prepare for the coming flu season by allowing all hospitals to treat swine flu patients.
If an infection is suspected, people need to call a fever consultation center first, and they will be advised to go to a hospital designated to handle patients with the new flu.
When the infection spread in Osaka during and after the Golden Week holidays in May, fever consultation centers were deluged with 60,000 calls between May 20 and 31, an official in the prefectural social welfare division said.
The Tokyo Metropolitan Government received 4,985 calls on May 20 alone when it was confirmed that two high school students in the Kanto region were infected with the new flu. The number was triple the calls received two days before. In total, there have been 78,550 calls in Tokyo seeking a consultation as of Monday.
Tokyo currently has 67 hospitals assigned to treat patients with swine flu. The metropolitan government is asking more hospitals to be ready in case the outbreak gets worse, although an official in the health bureau refused to say how many hospitals have signed up.
The government needs to prepare now for the possibility of a swine flu outbreak in autumn because the number of patients could be much higher, Sugaya said.
"Specially designated hospitals (for swine flu) won't be enough if tens of thousands of people are infected," he said.