The H1N1 Pandemic: Is a Second Wave Possible?
by ilene - December 11th, 2009 11:35 pm
The H1N1 Pandemic: Is a Second Wave Possible?
Since early November, cases of H1N1 have continued to decline nationwide, and scientists keeping track of the numbers say that as pandemics go, 2009 H1N1 may turn out to be a mild one — at least for the time being.
The question now on health officials’ minds is: Will there be a second wave of cases in the new year? The answer depends on whom you ask. "We took an informal poll of about a dozen of some of the world’s leading experts in influenza," Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention (CDC), told reporters recently. "About half of them said, Yes, we think it’s likely that we’ll have another surge in cases. About half said, No, we think it’s not likely. And one said, Flip a coin."
It is an accurate reflection of how unpredictable the influenza virus can be. Although flu activity has been waning for the third week in a row, health officials warn that there are still four to five months left in the official influenza season, plenty of time for the virus to make its rounds and find new hosts. "The story of pandemics, and the story of H1N1 in general, is the story of persistent uncertainty where we never quite know what we are going to get or when," says Dr. Irwin Redlener, director of the National Center for Disaster Preparedness at the Columbia University Mailman School of Public Health.
How severe the current H1N1 pandemic seems depends on what you use as a measuring stick. Compared with previous pandemics, like the 1918 Spanish flu, which killed 20 million people and infected up to 40% of the world’s population, or even the far less deadly 1957 and 1968 bouts with a strain of H1N1 influenza similar to the 2009 strain, things don’t seem as bad this time around. Fewer people are getting severely ill when infected, and fewer have died or required hospitalization from the flu than in previous pandemics.
Marc Lipsitch, an epidemiologist at the Harvard School of Public Health, and his colleagues studied the course of the 2009 H1N1 pandemic last spring in two cities — New York and Minneapolis — and determined that 0.048% of people who developed symptoms of H1N1 died, and 1.44% required hospitalization. Based…