More than a week after warning a swine flu pandemic was “imminent” by raising the alert level to Phase 5, an action taken days after the first signs of the epidemic appeared in North America, the World Health Organization (WHO) has not yet declared a pandemic. Spread of the virus appears to be on the decline in Mexico, while elsewhere new cases of illness continue to be reported but have generally been mild.

The unexpected trend of mostly mild disease in the current ‘wave’ of the epidemic means that officials could have a hard time alerting some people and the media to future warnings about a more severe A/H1N1, or another potentially pandemic virus, says Peter Sandman, a risk communication consultant based in New Jersey.

“Warning fatigue” is a real concern, adds Sandman, who has previously advised the US government on communication of risks including the H5N1 virus. “But when risk communication is well done, it’s usually a fairly small problem.”

As the current swine flu epidemic unfolds, it appears not to be quite as overwhelming a situation as the word “pandemic” might conjure for the public. In the media, the initial flurry of reports about cases of swine flu has now given way to mixed messages and uncertainty about how serious the current epidemic might become. Sandman says a big chunk of the audience is probably irritated by having a sense that they’ve ‘fallen’ for an unnecessary, false alarm.

“If and when WHO is compelled by its own criteria to declare H1N1/swine flu a Phase 6 pandemic, people may feel even more betrayed: 'you finally got your pandemic and it’s no big deal',” Sandman points out.

Measuring the scale of the threat early on in the course of the epidemic is difficult because data are sparse, says Barbara Reynolds, Crisis Communications Specialist at the US Centers for Disease Control and Prevention (CDC). It isn’t unusual to have more questions than answers at this stage, she adds.

“The perception of threat is personal and situational,” explains Reynolds. “People will lose interest if the threat does not seem real.” But if it does become real to them, the hope is that the CDC has communicated what they can do to help or how to get more information, she says.

According to the CDC’s risk communication framework, the past two weeks fall under this “initial stage of the emergency,” according to Reynolds. In this day and age news must go out quickly and in small chunks, she points out. “As we learn more, we share it... [and] we adjust the health recommendations.”

Sandman believes health authorities have erred on the side of over-reassuring the public, but not everyone got the same message. “Though the authorities were not fear-mongering, in my judgment, they left a significant part of their audience believing that they were.”

Not everybody reacts in the same way to an emerging threat such as this, explains Sandman. A large part of the population never takes the issue seriously, while on the other extreme a minority over-react. Then there are two groups in the middle ground, he says. There are those people who take the threat seriously at first and then feel betrayed when the situation turns out to be less dangerous than it first appeared. The other, smaller group takes the warnings exactly as they are meant, reacting according to the scale of the risk as communicated by authorities at any given time.

“We need to persuade people who became alarmed (wisely) and then became less alarmed (also wisely) that they have nothing to feel foolish about and nothing to feel angry about... but good reason to remain vigilant,” says Sandman.

The key is to be "scary" and “tentative” at the same time, explains Sandman — a tricky task when people may be inclined to heed one side over the other. The balance is achieved routinely with risk communication in other emergencies, he notes, including warnings about an impending hurricane, or fire insurance. People living in hurricane-prone areas evacuate time and time again, he points out. “When the year ends without a house fire, people aren’t angry at the insurance company.”

But the task is difficult with a new infectious disease for several reasons. “Neither the experts nor the public has any sense (intuitive or statistical) of the odds that a novel virus will launch a disaster, an inconvenience, or a false alarm,” explains Sandman. For this reason communicating uncertainty is much more important, he adds, and difficult.

Being clear about the constantly changing situation and dispelling misperceptions is important in early communications during the emergency, according to Reynolds. “The key is to tell the public from the very beginning what we know and what we don’t know.”

“However well I think the uncertainty was communicated, in all too many cases the message didn’t get through,” says Sandman. There are several “outrage components” that lead people to react emotionally in these unfamiliar situations, he explains, and this helps the “scary half of the message” to get through more clearly.

Past experiences have made the task even more difficult, according to Sandman. Many people got the impression that officials have been “promising” an H5N1 pandemic which hasn’t come yet, he points out. And the 2003 outbreak of severe acute respiratory syndrome (SARS) came across to many people as a false alarm, not a lucky break.

If the swine flu epidemic continues to move slowly while posing a more distant threat, the public could become desensitised to risk messages. If people become complacent, or even lose trust in the officials’ handling of the emergency, this could undermine how well risk messages might work.

“All this, of course, will make it all the harder to achieve the right balance of scary and tentative when talking about the possibility that H1N1 could become more virulent (and more transmissible) at any time, perhaps in a second wave,” Sandman predicts. “It will make it all the harder to revive warnings about H5N1.”

“We do know that this event provides an important opportunity to raise awareness about the steps people can take to help themselves and their community,” Reynolds points out. “A basic principle of [the CDC’s risk communication framework] is to reduce anxiety and restore a sense of self-control.”