Vaccinating all schoolkids could prevent flu pandemic

The key to stopping a flu pandemic may lie in schoolchildren.

At school, kids are close together, they don't practice the best hygiene, and they help germs spread like pollen in spring. At home, they do the same with their families.

Giving them the best available vaccine at the earliest sign of a major epidemic might fend off a deadly pandemic, say two of the nation's most prominent influenza researchers, newly arrived at the Fred Hutchinson Cancer Research Center.

"A lot of people believe kids are the best transmitters of the virus, and with a limited supply of vaccine, this might work," said Elizabeth Halloran, who has studied epidemics for decades.

Halloran and her colleague, Ira Longini, believe using available vaccine would buy time for manufacturers to create a vaccine that matches the pandemic flu virus exactly and would protect millions of people worldwide.

Writing in the journal Science, they recently called for a nationwide study of vaccinating schoolchildren against conventional flu to see if that controls widespread transmission. (Present guidelines call for immunizing young children, older adults, pregnant women, chronic-disease patients and close contacts of these people.) Smaller studies have suggested the schoolchildren approach might work, and federal officials have expressed interest in Halloran's and Longini's suggestion.

Indeed, public-health officials usually listen when Halloran and Longini speak.

The pair have used their expertise in statistical modeling of epidemics to advise the White House and others on both pandemic flu and smallpox. They also have a wide background in how other infectious diseases spread, including HIV and malaria.

"They are the experts in this area," said Bradley Efron, chairman of the statistics department at Stanford University. "They're definitely at the top of their game."

Longini and Halloran, who came to the Hutchinson Center in January from Emory University in Atlanta, have worked together for 16 years. They will be key figures in a new vaccine-research center planned with the University of Washington, where both teach in the department of biostatistics.

That will include more studies on reducing disease transmission and better understanding the ways that the human immune system responds to different diseases.

The proposed nationwide study of immunizing schoolchildren against the flu would help prepare for pandemic flu in another way, the scientists said: Expanding the vaccinations would cause manufacturers to increase production capacity and refine distribution channels.

Longini and Halloran said they have no doubt of the threat of a pandemic flu. Both say they think it will come from a mutation of the bird-flu virus, H5N1, that has killed about 113 people, most of them Asian poultry workers, and caused the destruction of millions of chickens. The fear among global health officials is that even a slight genetic change in the H5N1 virus could make it easy to spread between people.

Longini, 57, estimates that in a worse-case scenario, as many as 2 billion people could become ill worldwide and 50 million could die within the first six months.

A recent Carnegie Mellon University survey of 19 influenza experts created a "median worst-case estimate" of 6 million deaths in the United States in an extended epidemic and 180 million worldwide.

Halloran and Longini are internationally known for their modeling of epidemics using U.S. census demographics and travel data from the U.S. Department of Transportation to calculate how a pandemic would spread in the United States.

The technique considers the likelihood of any two people meeting on any given day in various settings, such as the workplace or home, where transmission might be more likely. It considers that about a third of the population would never have flu symptoms but could still be contagious, and it accounts for the fact that infectious periods vary.

"It takes into account the real world," said Longini.

Last summer, Longini, Halloran and their colleagues used their modeling to give the world a glimpse of hope: They proposed a scenario in which a strain of deadly flu could be contained at its source.

The scientists simulated a Southeast Asian community with a population of 500,000, based on the 2000 census of Thailand and a previous study of social networks in the Nang Rong District in Thailand. In the model, people in the community mixed in many settings, including homes, schools, workplaces, shops and temples.

The researchers predicted that the disease could be contained if about 70 percent of those who had contact with infected people received antiviral drugs within 21 days, assuming a moderately contagious virus. They estimated that 100,000 to 1 million courses of the drug would be enough to contain the disease and treat the community.

But its success would depend on several factors, including how quickly the mutated virus was detected, how communicable it was, how fast the World Health Organization could ship drugs to the community and how fast the targeted people could be treated.

"We do have [limited] stockpiles of antivirals," Longini said. "If they were used in a well-targeted way, we could slow the spread long enough to produce a matched [effective] vaccine. If we mitigated the first wave of the pandemic, it might not be so catastrophic."

Warren King: 206-464-2247 or wking@seattletimes.com