Spring 2009: Register
Courtesy Colin Russell
The Next Flu Pandemic
Tracking the migration of influenza virus across six continents
By Mary J. Loftus
The math is fairly straightforward, if a bit alarming.
“History tells us there has been a flu pandemic every twenty to forty years, and the last pandemic was in 1968,” says Colin Russell 99Ox 01C.
Russell, a research associate at the University of Cambridge in the Department of Zoology and a member of the Cambridge Infectious Disease Consortium, studies the epidemiology of influenza viruses.
A recent discovery by Russell and colleagues about where flu strains originate may help to make the viruses’ path more predictable, as well as improving vaccinations.
The global migration of flu viruses has been a mystery until now, says Russell. But by analyzing data from eighty countries, he found that flu viruses continuously circulate in the Far East until a traveler picks up a strain and carries it to Europe, Australia, or North America, where it can cause an epidemic.
Russell, Emory’s first Gates Scholar, was a biology major at Emory’s Oxford College, intending to become a doctor, when he discovered a love of scientific research. Along the way, he became intrigued with pathogens, rabies, and, ultimately, the flu virus because of the “richness of available datasets, the breadth of fundamental unanswered questions, and the opportunity for major public health impact. Also, influenza viruses evolve so quickly we can watch evolution in our lifetimes.”
By analyzing 13,000 samples of influenza A (the most common type of flu virus) collected across six continents from 2002 to 2007 by the World Health Organization (WHO) global influenza surveillance network, Russell and other scientists discovered that outbreaks are seeded by viruses that originate in East and Southeast Asia—circulating among China, South Korea, Singapore, and the Philippines—and then migrate around the world. The findings were reported in the April 2008 issue of Science.
Annual influenza epidemics are thought to infect 5 to 15 percent of the world’s population each year, causing three to five million cases of severe illness and between 250,000 and 500,000 deaths annually, according to the WHO.
Because the flu virus evolves so quickly, there are a number of challenges involved in making the vaccine. Each year in February and September, a WHO committee meets to select the strains of flu to use in the influenza virus vaccine for that year by deciding which strains pose the greatest threat for the next flu season.
The vaccine does a good job of protecting the 300 million people vaccinated each year, says Russell, but sometimes a new strain infects people after the vaccine already has been produced.
Avian flu is still a general risk, in addition to the overdue pandemic. But it’s important that we limit the impact of the flu as much as possible every year through vaccinations and antiviral drugs, Russell says.
“The epidemic in 1918 was bad, very bad; 1957 and 1968 were also bad but only about five times worse than a normal year of seasonal influenza,” Russell says. “About 2.5 million people died in the 1968 pandemic, but about 20 million people have died since then from seasonal flu. After a pandemic is over we’ll be left with years upon years of seasonal flu.”