It has been an unusual year for flu. But the virus always catches us by surprise. Last year the first pandemic of the 21st century, caused by a "novel" H1N1 virus dubbed swine flu (because it originated in Mexican pigs), was less nasty than feared. The 65,000 deaths it was estimated might result in May, under a "reasonable worst case scenario", were reduced to 1,000 by September. In the end there were 484 confirmed deaths from swine flu.
This year it has returned – and behaved differently. Instead of peaking in the summer – very unusual for flu – and reappearing in the autumn to hang around at low levels for three months, it did not take off until mid-December and was accelerating fast at New Year. Experts warned last week of a surge in cases as children returned to school but when the latest figures came on Thursday they showed a small decline, from 124 per 100,000 population to 99 per 100,000. Cases always fall at Christmas because there are only three working days to report them, but it is unlikely there will be an epidemic this winter. By the time you read this, cases may have peaked or be about to peak. However, even if the worst is over, flu will still be about for another month or two so take precautions to protect yourself and your family.
Is swine flu dangerous?
For most people, no. Many people won't even know they have had it. In others it can be an unpleasant illness – cough, fever, aches and pains. The best treatment is a hot drink, a couple of paracetamol and bed rest. But in a few it can be nasty and it needs treating with proper respect.
How is swine flu different from seasonal flu?
In the past, seasonal flu has targeted the elderly, while swine flu targets younger adults and children. Nine out of 10 of those hospitalised with swine flu this winter have been under 65. Pregnancy increases the risk: it lowers the immune response and the lungs become compressed as the baby grows, increasing the risk from respiratory infections. Other groups at risk include the obese and those with chronic respiratory or neurological conditions.
What flu is around this year?
There are three strains – H1N1 swine flu, H3N2 seasonal flu and flu B. Swine flu is dominant and has become the main virus causing seasonal flu, accounting for most of the deaths and hospitalisations. As it largely spares the elderly they have been less affected. Swine flu is expected to remain a principal seasonal strain for many winters to come.
How bad is it?
There are two contrasting pictures. If you look at the number of cases in the community, based on consultations with GPs, they are broadly what we would expect in any winter
If, however, you look at the numbers in intensive care, they are high, several times the number last year. The explanation may be that flu is no worse but all the severe cases have come in a few weeks instead of being spread over a few months. Flu behaves differently every year.
Is it worth being vaccinated?
Definitely, if you are pregnant or you are in an at-risk group. The vaccine protects against all current strains. But it is late in the season. It takes seven days from the date of the jab to provide partial immunity and two to three weeks to develop full immunity. If you are going to have the jab, have it now.
What about other viruses?
There are the usual collection that cause winter viral illnesses every year – colds, coughs, bronchitis, vomiting and diarrhoea. Densely populated cities provide ideal breeding grounds. The average adult gets two to five colds a year. Schoolchildren suffer worst, with seven to 10 colds a year. Young children, with undeveloped immune systems, are the most vulnerable and form the main reservoir of infection. Most colds are transmitted at home or school and adults in regular contact with children are most at risk of infection. Hospitals are under pressure from these and the weather has added to the problems by increasing the number of falls and fractures.
What is the best protection against catching winter viruses?
Personal hygiene. Wash your hands often and try not to touch your nose and eyes when out and about – they are the key route of access for viruses. Your fingers are easily contaminated with viruses by touching door handles or shaking hands. These are transmitted to the mucous membranes of your nose and eyes (tears drain into the nasal cavity, passing viruses to the nose). Social kissing is OK – the cold virus is lodged in the back of the throat and is unlikely to be transmitted via a kiss. Cold viruses spread by touch or by large particles expelled at close range by coughs and sneezes.
Why are viruses worse in winter?
It is partly that we huddle together for warmth in crowded offices and buses and trains, encouraging viruses to spread. The nose dries in low temperatures or dry air-conditioning and respiratory viruses get trapped and reproduce. Wearing a scarf round your nose and face protects them from plunges in temperature.
Do vitamin C or echinacea help?
There is no good evidence either can prevent a cold or hasten recovery from one. The Nobel Prize winner Linus Pauling popularised the idea of taking daily doses of vitamin C to ward off colds. Its sales soared. However, only a very small proportion of people in the West are likely to have a deficiency of vitamin C and it is unlikely a daily dose will provide a benefit. Echinacea is the most popular preventive treatment for colds and is supposed to help halt infection by boosting the immune system. It is claimed it can abort a common cold infection and prevent the development of symptoms, but there is no evidence for this.
How do you tell the difference between a cold and flu?
With difficulty. Severe, genuine flu is characterised by an irresistible and often sudden desire to lie down. It is accompanied by fever, muscle aches and pains and a general feeling of malaise. It's nasty. Fever, aches and malaise can also occur with a heavy cold, though this is unusual. Both flu and colds may also be mild.
What is the best remedy?
Only the immune system can cure a cold or flu. In most cases, it will take four to seven days to get over a cold and will not require treatment. The same goes for flu. Tamiflu helps shorten its length and may curtail its spread, but it is not a "cure". Aspirin, paracetamol and ibuprofen relieve headache, sinus pain, sore throat and aches. Nasal drops to clear a blocked nose can be helpful before sleep. Any hot drink eases a cough and sore throat – but standard cough medicines are no better than a placebo. Gargle with half a teaspoon of salt in a glass of water instead. Spicy foods and hot soups are beneficial. A strong immune system is the best defence against infection – eating healthily, exercising and getting enough sleep will boost it.
When should you call a doctor?
If you have a high prolonged fever (above 102F, or 103F in a child), trouble breathing or symptoms that last for more than 10 days or get worse, not better. In a child, bluish skin, earache, vomiting or a changed mental state are alarm signs. In an adult, pain in the chest, fainting, confusion or persistent vomiting.