With no major health organization advising delay, the Radiological Society of North America is moving forward with its 2009 meeting, despite evidence suggesting the week-long event will be held in the midst of an H1N1 flu epidemic.

More than 60,000 people are expected to attend the RSNA scientific sessions and technical exhibits at McCormick Place in Chicago Nov. 29 to Dec. 4.

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The RSNA is holding to its position against delay or cancellation while staying in close touch with the federal Centers for Disease Control, Department of Health and Human Services, Office of Homeland Security, World Health Organization, and with Chicago's Metropolitan Pier and Exposition Authority, board chair Dr. Burton Drayer said in an interview.

"Our first priority is the health and safety of everyone attending," he said. "We are not going to have a meeting or do anything if there is any type of risk."

In a Sept. 15 interview, CDC spokesperson Tom Skinner confirmed the center has made no recommendations about delaying or cancelling large group meetings. The agency would take those steps if the virus were highly virulent, easily transmitted, and quickly spreading.

"We are not there at this time," he said.

As of Sept. 25, WHO attributed more than 3900 deaths worldwide to the A/H1N1 virus. More than 319,000 cases were confirmed, though the actual case count is significantly higher because many mild cases are not recorded, according to a WHO report. In Illinois, 19 deaths and 438 hospitalizations have been attributed to the disease since January.

Yet specific characteristics of H1N1 appear to mitigate the potential risk for people most likely to attend the RSNA meeting. According to the CDC, the infection rate is highest among people in the group aged five to 24 years. Its virulence drops off appreciably for middle-aged and older adults.

In most instances, the flu causes moderate illness, typical of past flu outbreaks, according to CDC director Dr. Thomas Frieden. During a Sept. 25 press briefing, he said the future course of the disease is unpredictable, but its genetic makeup has been stable. That suggests the virus is not likely to become deadlier, and the H1N1 vaccine will be effective.

Frieden estimated 50 million doses of vaccine will be ready for use at 90,000 locations in the U.S. by mid- to late October. It will be typically effective against the disease from 10 to 15 days after inoculation.

To do its part, the RSNA is following most CDC recommendations for minimizing the risk of spreading the flu at the meeting. Precautions include:

The RSNA is working with Chicago health authorities to make sure hand sanitizer is widely available at the convention center, hotels, and airports. Hand sanitizer will be included with conference materials for each attendee, Drayer said.

The RSNA will monitor individuals at the meeting. People with flu-like symptoms will be discouraged from attending, Drayer said.

The society has yet not developed contingencies to follow the CDC recommendations for creating alternative options for participation, however.

"If we decide to do that, it would be an opportunity to see what we could do in terms of web-based viewing," Drayer said. "But we don't have a formal plan."

The RSNA also deferred to the CDC on specific guidelines for who should get the H1N1 vaccine. The federal agency favors immunization for pregnant women, people who live with or care for children younger than six months of age, healthcare and emergency medical services personnel, persons between the ages of six months and 24 years, and people between the ages of 25 and 64 years who have an elevated risk because of chronic health disorders or compromised immune systems.

Though many meeting attendees won't fall under the guidelines, Drayer said it would not be appropriate for the RSNA to recommend vaccinations for everyone planning to attend the meeting.

However, on its website the RSNA urges attendees to get vaccinated. The site's "Tips for Staying Healthy" advises a seasonal flu vaccine and the H1N1 flu vaccine when it is available. It notes WHO has not issued travel restrictions in the U.S. but advises potential attendees to stay home if they are sick.

The RSNA is also planning to use social media, e-mail blasts, the "RSNA News" newsletter, and the society's website to answer questions about H1N1 and its potential effect on the conference.

RSNA efforts attempt to balance the need for frank and accurate information without discouraging travel, according to Drayer.

"We want to express concern, but we don't to say anything that would provoke a panic," he said.

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