Containing Flu Is Not Feasible, Specialists Say
Many countries are still ignoring that advice. The globe is a confusing welter of bans, advisories and alerts on some pork and some people.
On Wednesday, Homeland Security Secretary Janet Napolitano was heavily pressed in Congressional hearings to ignore the advice and close the border with Mexico. She defended her decision not to do so, saying it “would be a very, very heavy cost for what epidemiologists tell us would be marginal benefit.”
President Obama defended it too, telling a reporter that it would be “akin to closing the barn door after the horse is out.”
Experts on the global movement of flu say Dr. Fukuda, Ms. Napolitano and Mr. Obama are right. The world, they say, must bow to the inevitable: closing borders would not only fail to stop the virus, but would also cause economic collapse and possibly add to the death rate.
“But it’s wrong to think we’re throwing up our hands and saying ‘Let ’er rip and let’s hope for the best,’ ” said Dr. Martin S. Cetron, director of global migration and quarantine for the Centers for Disease Control and Prevention in Atlanta. “This has all been in the national pandemic flu plan since 2007.”
Closing borders is dangerous because many goods needed in a pandemic are made abroad, said Dr. Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, including most masks, gowns and gloves, electrical circuits for ventilators and communications gear, and pharmaceutical drugs and the raw materials to make them. (For example, most suppliers of shikimic acid, the base ingredient in the antiviral drug Tamiflu, are in China.)
“You cut those off and you cripple the health care system,” he said. “Our global just-in-time economy means we are dependent on others.” Much of our food is from overseas. “A Kellogg’s Nutri-Grain bar has ingredients from nine countries in it,” he noted.
The fallback position, experts said, is mitigation, the use of “nonpharmaceutical measures.” They include personal ones like washing hands and wearing a mask, occupational ones like working from home or arranging care for children who are sick or whose schools close, neighborhood-level ones like closing theaters, museums or restaurants, and metropolitan-wide ones like shutting a school system or canceling a major league ballgame.
The three goals, Dr. Cetron said, can be plotted on the graph of new infections called the epidemic curve. “You want to shift the curve to the right, blunt the peaks and squash the area under them,” he said.
Moving right is slowing new transmissions until the arrival of hot summer weather, which is unfriendly to flu, and to buy time — the 16 to 20 weeks it takes to make a new vaccine.
Blunting the peaks of new cases decreases demand on hospitals, so patients do not have to be triaged off ventilators to die because others are waiting.
Ventilators cost $30,000 each, though models as cheap as $100 are stockpiled for pandemics. But patients whose lungs are delicate or mucus-jammed need professional monitoring. And fewer people infected per day slows the multiplier effect. Each one usually infects two or three more.
For the World Health Organization, mitigation is an about-face from the strategy that has contained the H5N1 avian flu, which has caused fewer than 300 deaths. That flu’s first appearance in 1997 was contained by killing every chicken in Hong Kong. Since then, each time a cluster appears, the public health authorities try to cull all the local poultry, vaccinate birds in a large ring around that, and drop the “Tamiflu blanket” on people — dosing everyone in the area.
The 1976 swine flu was also beaten by containment, said Dr. Pascal J. Imperato, dean of the school of public health at the State University of New York Downstate Medical Center, who was the chairman of the New York City Swine Flu Task Force in 1976. The 230 cases were all among soldiers at Fort Dix, N.J., “and they were all just held within that base,” he said. “They had no external contacts. One died, the rest had mild infection.”
Experts feared that flu was a re-emergence of the 1918 strain and that it would come back with a vengeance in the winter. They vaccinated 40 million people, but it never did come back.
In the 1918 Spanish flu, American cities that reacted quickly had fewer deaths than those that acted slowly and used fewer precautions, according to a 2007 study of 43 cities by researchers from the University of Michigan and the Centers for Disease Control. The most common combination was school closings and bans on public gatherings, which in 34 cities lasted for a median of four weeks. All those cities except New York, Chicago, and New Haven closed their schools; the median time was six weeks.
Deaths per 100,000 population ranged from 210 for Grand Rapids, Mich., to 807 for Pittsburgh.
Although some scientists and historians have argued that those measures just delayed deaths that later happened anyway, Dr. Cetron, one of the authors of the 2007 study, denied it.
“There’s no evidence of that,” he said. “Cities that acted early and layered on different interventions did well.”
Many people do not realize how long measures take to work. A child can shed flu virus for 10 days, Dr. Imperato said, an adult for 5.
Some experts are cautiously optimistic. A computer simulation of this outbreak released Wednesday by a team from Northwestern University projected a worst-case scenario, meaning no measures have been taken to combat the spread. It predicted a mere 1,700 cases in the United States four weeks from now.