Air Force Academy doc's study: A lot of what we think we know about swine flu may be wrong
A Flickr photo The Air Force Academy has punched swine flu in the snout.
We've all been told that the H1N1 virus, aka swine flu, is no longer contagious 24 hours after a person's fever has broken. But hold up a minute. A new study overseen by Air Force Academy doctor Catherine Witkop and published in the American Journal of Preventive Medicine focuses on a large group of cadets who contracted the virus over the summer -- and 29 percent of those with a fever under 100 after a full day, and 19 percent who showed no symptoms at all during the same time frame, were still shedding virus. Translation: around one in five cadets, and possibly more, might have been able to pass along the flu even after they were supposedly safe to be around.
So how has the Center for Disease Control responded? By saying, basically, "That's very interesting -- but we're sticking with the 24-hour rule."
The Academy hasn't: Witkop says cadets with H1N1 are being isolated for seven days, not just one, and while she can't prove definitively that this strategy prevented additional problems, there hasn't been another outbreak since the first one. Still, she resists the urge to knock the CDC's advice. In her words, "It's a really tough balance to strike."
According to Witkop, "We've spoken to the CDC about our findings, and they're pleased we did the study and were able to get more information about the shedding of the virus. But their decision to go with the 24-hour fever-free recommendation for returning to work or school was based on not overly disrupting school and work and things like that. And if you delve deeper into their recommendations, they do talk about high-risk settings like healthcare facilities or child-car facilities, and say that these organizations may want to extend isolation periods, especially if the flu severity increases. They don't say how long, but I think our findings support a longer period of time, especially in those high-risk groups."
Witkop doesn't want to give the impression that her work has answered every question about how long someone with H1N1 will remain contagious. Far from it. "We don't know if viral sheddings equate to the ability to transmit the virus," she allows. "That's why you need to balance how disruptive staying out of work for seven days would be, since we don't know if the virus is still transmissible on the seventh day. But in a high-risk setting, you might want to err on the side of being conservative -- and here at the Air Force Academy, we're using the seven-day period because our cadets live in such close quarters and spend so much time together.
"We implemented a very strict isolation area during the outbreak this summer -- one that would be difficult for a lot of universities and colleges and communities to implement," she goes on. "Our cadets were in a separate dorm area and weren't exposed to well cadets. And we also took a lot of other public-health measures, like hand sanitizers throughout the dorm. It's hard to know which of these factors was instrumental in quelling the cases, or if it was a combination of things."
At this point, Witkop can't investigate the transmissibility of the sheddings two, three or more days down the line for the best of all reasons: There aren't currently enough swine-flu patients at the Academy to make such a study viable. "We have a very low level of cases right now -- in the single digits," she says. "And that's the way we want to keep it." These H1N1 sufferers are self-isolating in their dorm rooms rather than being moved to a separate facility -- "but we do provide them with a fair amount of education about how to prevent the spreading of the virus to others around them."
The success of this approach to date convinces Witkop that it's worth continuing at the Academy -- not that she thinks anyone who believes otherwise is engaging in dangerous behavior. "The CDC has a lot of information, and I think they're making very realistic recommendations," she says. "But hopefully our study will help researchers provide even better guidance in the future."