A mild winter may have caused flooding, but it isn't all bad news: The warm weather has left the UK on course for a record low of cases of flu and respiratory disease

This winter looks like setting a new record for the lowest ever level of seasonal flu (Rex)

Amid the deluge – a ray of sunshine. We may be experiencing the wettest winter on record but, on present trends, this winter looks like setting another, more welcome, record – for the lowest ever level of seasonal flu.

Whether the storms have blown the bugs away, the rain has washed them into the ground or the mild weather has rendered us less susceptible to infection, is unclear. Possibly all three. More likely the miserable conditions have reduced the numbers going out and congregating in crowded places where the virus can spread.

The figures from the Public Health England tell their own story. The consultation rate for flu-like illness with GPs in the first week of February - the latest available - was 3.1 per 100,000 people in England – a tenth of the normal seasonal level, which is 30 to 200 consultations per 100,000.

Flu usually peaks before Christmas, if it is going to be an epidemic year. But throughout December and January it was running at levels more usually seen in summer. Experts warn that the season is not over yet - on rare occasions in the past, flu has risen sharply after mid-February. But as the evenings lengthen and Spring approaches, it looks less and less likely that we will see a significant outbreak this winter.

It is not only flu that is in downward decline. All infectious respiratory illnesses, including acute bronchitis, are becoming less common and look like marking record lows this winter. The decline in smoking is likely to be a key factor here.

No one can have been more pleased than Jeremy Hunt, the health secretary. Despite warnings that Accident and Emergency departments were at breaking point through the autumn, they have coped almost without incident through the winter. Flu usually causes long delays in A&E – especially when combined with icy weather causing falls and fractures – and NHS waiting lists lengthen.

Yet hospitals too have succeeded in keeping queues for in-patient treatment in check. Though the number waiting over 18 weeks is up on a couple of years ago at 6.4 per cent, it is not markedly so, and the longest waiters are dramatically down - those queuing over 26 weeks have more than halved since December 2010.

The record low for this winter's flu is the culmination of four decades of steady decline in the impact of the illness, punctuated by the occasional epidemic. The biggest drop has been in children under five who, until this year, have not been eligible for vaccination. For all age groups, better hygiene, less pollution causing fewer respiratory infections (which provide an opportunity for the flu virus to spread), more people self-treating at home (not counted in the GP consultation figures) and changes in the natural cycle of the disease are among the reasons put forward by experts.

Professor Nick Phin, a flu expert at Public Health England said: “I suspect we are seeing a real reduction in flu but whether it is on the scale of the GP consultation data is a moot point. There has been a change in behaviour among patients with more treating themselves at home instead of going to the GP. Even if the prevalence of flu has not changed that would lead to a fall in consultations.”

The panic over the 2009 Swine Flu pandemic already seems like a distant memory. That caused widespread illness and over 1,000 deaths in the winters of 2009-10 and 2010-11. It was a new strain of virus that originated in pigs in Mexico to which certain groups, such as pregnant women, proved particularly susceptible. Intensive care units were overwhelmed and GPs were turning patients away because of a vaccine shortage.

Yet that episode may have helped loosen seasonal flu’s annual winter grip – by boosting vaccination rates. Flu vaccination has been available since the 1970s but only became widespread after the national flu vaccination programme began in 2000, offering free jabs to the over-65s and those with chronic illnesses such as asthma.

Since the 2009 swine flu pandemic, the programme has been extended to pregnant women and, this winter, to children aged two and three. Latest figures show around 40 per cent of two and three year olds have been vaccinated, 40 per cent of pregnant women, half of those with chronic illnesses under 65 and nearly three quarters of the over-65s.

The plan is to extend vaccination to all children aged two to 16 within the next two to three years. Professor Phin said: “We believe children are the main spreaders of the virus. If we can protect them from flu and from the complications it causes, such as otitis media [middle ear infection], we may also be able to reduce its impact in the community.”

However, there are doubts about effectiveness of the vaccine which is known to provide limited protection, especially in older people. Critics have claimed it has been “over promoted” and “over hyped” in what has become an annual bonanza for the drug companies who profit from the £120 million annual flu vaccination campaign.

A 2012 report published by the Centre for Infectious Disease Research and Policy (Cidrap) at the University of Minnesota in the US, concluded the flu shots of the kind given in the UK containing inactivated trivalent vaccine provided 59 per cent protection in healthy adults aged 18 to 64, but less in older people who tend to have a weaker immune response.

Professor Phin said: “I have always acknowledged that the vaccine does not provide near 100 per cent protection. It is more like 60 to 70 per cent. In older people it can be down to 30 to 35 per cent. But 35 per cent protection is better than nothing at all. We continue to push for more research to develop a more effective vaccine that provides longer protection and against a wider spectrum of strains.”