The formal declaration of a global flu pandemic is bound to trigger anxiety and possibly panic.
It's one thing to say Britain is having outbreaks of swine flu – but quite another to talk of being in the grip of a fully fledged, officially designated worldwide pandemic.
But public health officials in the UK are already trying to talk down the implications of the World Health Organisation moving the alert status from level 5 to level 6, the highest.
Swine flu in most countries has been mild and there have been no signs of it becoming more deadly. The pandemic tag is to do with geography, public health experts say, and not severity.
Swine flu has to be officially designated a pandemic because it is spreading easily in two distinct regions, the Americas and now Australia.
In England, the Health Protection Agency, which is notified of every case, says there is no sustained transmission and containment of the virus is still the policy. "We still have cases that have been linked to an outbreak, such as in schools, or linked to other cases," said a spokeswoman. "The big change would be if we had sporadic cases."
Scotland is taking a different tack. The Scottish health secretary, Nicola Sturgeon, told the parliament this morning that hospital cases in Scotland were at similar rates to the United States. There are 311 confirmed cases of H1N1 in Scotland, more than a third of the UK's total, with cases heavily concentrated in the Glasgow area. By yesterday, 18 people had been admitted to hospital, with five in intensive care or high-dependency units. Fifteen schools and nurseries are either entirely or partly closed.
Sturgeon says containment has failed, so the strategy in Scotland is to mitigate the spread. Doctors in the worst-affected areas – Glasgow, Dunoon and Paisley – will be allowed to make a swine flu diagnosis in their surgeries rather than wait for specialist or laboratory tests. Only the closest contacts of infected people will be given the antiviral drug Tamiflu.
"We have seen a rapid increase in the number of confirmed cases in Scotland over the past 10 days," Sturgeon told parliament. "Based on this experience, Health Protection Scotland has expressed the view that sustained community transmission appears to be taking place."
In England, the containment strategy continues for now. Every case is reported and close contacts are given Tamiflu, which reduces the flu's duration and severity. Where schoolchildren have fallen ill, every pupil has been given the drug and most schools involved – though not all – have been closed.
The aim is to stop swine flu spreading. If containment fails, that policy will end, and stocks of Tamiflu will be preserved for those most at risk of severe illness. There will be no more mass dosing of schoolchildren.
Little else will change with the official pandemic announcement. The government is rolling out its anti-pandemic strategy as fast as it can because there is every possibility that swine flu could do a lot more damage once the winter flu season starts.
Plans involve sending antiviral drugs and antibiotics to all GPs, and advertising campaigns telling people to wash their hands and if they fall ill, to stay at home, call the flu line and get a friend to collect their drugs.