A second team of researchers looked at 26 elementary-school students in Pennsylvania and their household contacts who had tested positive for H1N1 to assess virus "shedding patterns."
"We found the median duration of shedding to be six days, with a minimum of one day and a maximum of 13 days," said study author Dr. Achuyt Bhattarai, an epidemic intelligence service officer with the CDC.
The same numbers were found in children over the age of 9, representing a longer time frame that is typically seen in adults. Bhattarai said, "this is consistent with earlier studies of seasonal flu."
This and future data should help officials decide when children should be allowed to return to school.
The teleconference also addressed the current delays and shortages in available H1N1 vaccine.
"We're all disappointed and frustrated by the current situation with the vaccine supply but we need to recognize we're not alone. The situation is true globally," said Dr. Bruce Gellin, director of the U.S. Department of Health and Human Services' National Vaccine Program.
The situation points up problems in the current vaccine production system, which relies on eggs as incubators of the virus.
"There's certainly lots of room for improvement in these systems," Gellin said. "Some of the early issues are resolving, particularly real difficulties with yield and variability among manufacturers. Some yields were half what was expected, some were less than half. That was a large part of the issue. We're encouraged that many of these things are being optimized and it's the same with the seasonal vaccine every year. We continue to do tune-ups which are going to translate to more doses over the coming weeks and hopefully then, the lines will get shorter."
There's more on H1N1 flu at the U.S. Centers for Disease Control and Prevention.
SOURCES: Oct. 29, 2009 teleconference with: Bruce Gellin, M.D., director, HHS National Vaccine Program Office; Natalie Janine Dailey, M.D., epidemic intelligence service officer, North Carolina Division of Public Health Communicable Disease Branch; Achuyt Bhattarai, M.D., epidemic intelligence service officer, U.S. Centers for Disease Control and Prevention; and Rear Admiral Stephen Redd, M.D., director Influenza Coordination Unit, CDC