An spike in flu cases among children could indicate a rise in demand for adults “further down the line”, an expert has warned.

Saffron Cordery, interim chief executive of NHS Providers, said the NHS is “bracing” for a challenging winter.

It comes after health officials warned that hospitals are dealing with a “quad-demic” of disease, with rising levels of flu, Covid-19, norovirus and respiratory syncytial virus (RSV).

We’ve seen a real rise in, a spike in, the number of children who are suffering from flu in particular, and often that’s a predictor of a later wave coming in adults

The number of people in hospital with flu has quadrupled compared with last year, according to figures for the NHS in England.

An average of 1,099 flu patients were in hospital beds each day in the week to December 1, including 39 in critical care.

A record number of people are occupying hospital beds for this time of year because of a variety of illnesses and injuries, with England’s provision about 95% full.

“Quad-demic – it’s an awful word, but it does mean that we’ve got four different viruses running around at the moment – we’ve got flu, we’ve got Covid, we’ve got norovirus and RSV, and all of those coming together makes it incredibly challenging,” Ms Cordery told BBC Breakfast.

“I think there are two things that it does: one is it really increases demand for services, particularly, I would say, GP services, but also A&E services.

“And of course, those staff who are working in our hospitals are also those who are living in our communities who are affected by the same viruses, or their children are affected by those viruses, so it does, of course, reduce the number of staff who are available to work.

“Those two things coming together is what puts enormous pressure on services on the front line in winter.”

She added: “We’ve seen a real rise in, a spike in, the number of children who are suffering from flu in particular, and often that’s a predictor of a later wave coming in adults.

“So it’s likely that we might see rising demand in adults further down the line.

“So yes, we are bracing ourselves, I think, for a challenging winter ahead.”

Health leaders have urged people eligible for a free flu jab to get their vaccination “as soon as possible”, with the NHS booking system due to close in around two weeks.