It is every parent's nightmare: your child has the flu. But she seems to be getting better and is more herself, so you stop worrying. Then, all of a sudden, out of the blue, she stops breathing and dies. That is what happened to three-year-old Tamara Whitty of Worcester. She seemed to be on the mend - in fact, she was dancing to Top of the Pops. Then later that night she collapsed, fighting for breath, and died. Doctors believe she had the Fujian strain of flu, which has killed four people in Scotland, two in England and one in the Irish Republic. At least three other deaths of children are being investigated as possible Fujian flu cases.

Doctors now know a great deal about types and strains of flu, where they are from, what is new and what they can do to you. Type A flu strains - of which Fujian is one - are considered by virologists to be the most worrying. Fujian flu arrived in Britain this year from Australia, where it killed 3,000 people during the Australian winter (our summer). The records in Australia, however, don't show the ages of those who died.

So how much should we be worrying about our children this winter? Is this virus particularly deadly for them? "Children are like sitting ducks when it comes to the flu," says John Oxford, professor of virology at Queen Mary's, London. But this Fujian flu may not actually be any more dangerous than other new flu strains. The problem is, he says, that until now we have not been aware of how severe flu, in general, can affect small children. "The medical community has so far not focused on children, but on old people," Oxford explains. "These cases of Fujian flu have cruelly exposed this."

Until very recently, scientists did not have ways to accurately diagnose many kinds of flu. "In the past year or so, new rapid diagnostic tests for flu have been developed," says Oxford. These tests are more sensitive than before and, consequently, specialists now believe that rates of flu - and therefore the numbers of children who actually die from it - may have been previously "under-reported".

Each year many children die from respiratory illnesses, such as respiratory syncitial virus (RSV), or bacterial infections such as pneumonia. Oxford believes that some cases of flu may in the past have been mistakenly attributed to these causes. All young children are more "at risk" when it comes to flu, often simply because they will not have had the virus before and so will not have built up any immunity to it, as older children and adults may have. Young children are also more vulnerable to such illnesses in general, partly because they are small - their airways are narrower, and therefore more likely to block with a respiratory infection. Since they are physically smaller, the virus may also develop more quickly than it would in an older child or an adult. And young children have weaker immune systems, so the bug may take hold more powerfully. This does not, however, mean they will die from it.

We should not be panicking at the first sneeze. The recent cases of children dying from Fujian flu, though naturally shocking and therefore widely reported, are still extremely rare. And we are not, says Oxford, on the brink of an epidemic: "It's just an outbreak." Figures of people with flu were actually in decline last week, and, he says, "we should be relieved that we have not seen more of it".

However, as a parent, it is worth taking flu fairly seriously. This basically means keeping an eye on your child's symptoms in case they become severe. If you know that someone else in the family has flu, or that there has been flu at school,you should go on "orange alert", says Oxford. But though you should "treat symptoms seriously, there is no need to panic". Most children with flu will initially go off their food, and seem off-colour. (An older child can describe muscle aches and headaches, but your two-year-old will probably not be able to put these into words.) They may have a cough, or runny nose, and a high fever. Jon Couriel, consultant in paediatric respiratory medicine at the Royal Liverpool Children's Hospital, and chairman of the British Paediatric Respiratory Society, says that if your child is very floppy, lethargic and has difficulty breathing you should seek medical advice straight away.

But the problem with flu is that it has "no characteristic or distinguishing features to separate it from other common viral infections". In other words, doctors will have the same problem diagnosing it as you will. It is not known what makes one child gravely ill with flu while others will recover perfectly well from the same virus, so there is nothing you can do to stop your child's flu developing. But before we start stampeding to casualty wards with our runny-nosed children, says Couriel, we need to get the "dangers" of flu into perspective.

The average pre-school child, says Couriel, will have between six and 10 viral infections a year. Most of these are trivial (runny nose, sore throat and temperature - much like mild flu). Furthermore, he says: "The vast majority of children who do get the flu will not be terribly ill." In the unlikely event that your child does become seriously ill with flu and has to go to hospital, she is most likely to recover perfectly.

"There is excellent supportive care available," says Couriel. "Many children in this situation just need fluids, maybe intravenously, and simple drugs such as paracetamol for fever."

In a small minority of cases in which more respiratory problems develop, the child may need oxygen or ventilation but, he says: "In 25 years in respiratory paediatrics, I have only seen one or two children die of complications arising from the flu," whereas "each year, we get 300-400 admissions of children very sick with RSV". Flu, then, is not something that paediatric respiratory specialists are losing sleep over.

Oxford, however, believes that we do not have adequate systems to protect children against flu. It would, he says, be prudent to immunise all small children at the start of "flu season". Progress on this front is impeded by what he calls "MMR aggravation" - the scientifically groundless scaremongering over routine childhood vaccinations. "Many parents are suspicious of vaccines. It is parents who need to take a huge responsibility for holding us back in this area," he says.

In Britain, flu vaccine is currently recommended only for people over the age of 65, and anyone (child or adult) with underlying health problems, such as chronic asthma, heart disease or diabetes, or chronic chest conditions such as cystic fibrosis, who would be at high risk of complications. In the US, however, vaccinating children against flu, while not yet part of the standard immunisation programme, is much more common. Indeed, this year the US advisory committee on immunisation practices "encouraged" a flu vaccine not just for vulnerable children but "all healthy children six to 23 months of age". This is because "young, otherwise healthy children are at increased risk for influenza-related hospitalisations".

But is it safe? Yes, says Oxford: "In the 20 years it has taken to develop the flu vaccine there have been no unforeseen problems." Perhaps, then, the rare but devastating cases in which children such as Tamara die will, in future, be avoided. In the meantime, as parents, we need to be aware - but not over-anxious.