Is the Media Worsening Vaccination Rates?

Oct. 8, 2009— -- To many, the idea that those living in areas hit by the novel H1N1 flu pandemic this summer may have greater protection against the disease in the fall may be a comfort.

But some experts in infectious disease and public health fear a report in the New York Times today suggesting such a theory could cause the public to become complacent about the illness.

At the heart of the debate is the concept of "herd immunity" -- the idea that in a population in which a sufficient percentage of individuals are immune to a given disease, others within the population who have no immunity are still protected from infection by those around them.

It very well could be a concept that applies to the new H1N1 flu, noted Dr. William Schaffner, chairman of preventative medicine at Vanderbilt University in Nashville, Tenn.

"The story is based on reasonable surmise," Schaffner said. "The 'reluctance' of public health officials is because they are careful, data-based persons who are loathe to speculate even if the speculation has reasonable foundation."

But could such speculation lead the public to take the pandemic illness less seriously than they should?

"The idea that prior infection, whether symptomatic or asymptomatic, would elicit immunity ... is not surprising or unusual," said Dr. Edward Janoff, professor in the Infectious Diseases Division at the University of Colorado Health Sciences Center at Denver.

But, he added, "Since only a minority of the population has been exposed and infected so far, even if a substantial minority, there is no reason to withhold influenza vaccine or to avoid getting it. We don't really know who those exposed or immune persons are."

Dr. Carlos del Rio, professor of medicine in the Division of Infectious Diseases at the Emory University School of Medicine in Atlanta, agreed that while the theory bears consideration, it may be hard to determine whether it is reflected in reality.

"This is a very interesting observation, but I would not say that those cities that had the first initial wave are yet off the hook," he said. "The truth is that we really don't know."

Specifically, del Rio pointed out, an estimated 500,000 people in Mexico City became infected between April and June. Estimates from New York City hover around 1 million people infected.

"Is that enough to provide herd immunity?" he asked. "Maybe."