The number of patients in hospital with flu has fallen in England, but NHS bosses are warning the cold snap could increase the pressure on the health service in the coming days.

The start of January is normally the busiest time of year for the health service, so NHS England said the fall in flu cases was welcome.

Last week there were 2,676 people in hospital with the virus – down from just over 3,000 the week before.

But the UK Health Security Agency (UKHSA) has issued cold health alerts across England because of the freezing weather, meaning there is likely to be significant impact on the health service in the coming days.

The cold health amber alerts are in effect from 20:00 GMT on Friday until 10:00 on 9 January.

UKHSA warn impacts could include a likely increase in demand for health services, challenges keeping temperatures in hospitals and staffing issues due to external factors like travel delays.

NHS England medical director Prof Meghana Pandit said: “It is welcome news to see a drop in the number of people being admitted to hospital with flu, thanks in part to the extraordinary efforts of NHS staff with more than half a million more people vaccinated against flu compared to the same period last year.”

But she added: “The NHS is far from complacent as temperatures drop with this likely to increase pressures in the new year and demand on services remaining high with NHS 111 services recording their second busiest day in two years on Saturday.

“It’s vital that the public please continue to only use 999 and A&E in life-threatening emergencies and use NHS 111 and 111 online for other conditions.”

The drop in flu cases was expected as figures before Christmas showed the amount of flu circulating in the community had started to fall. Similar trends are being seen in the rest of the UK.

This was after the NHS issued dire projections that flu hospitalisations could rise to record levels, driven by a mutated version of the virus which is circulating this winter.

Experts say the virus could still bounce back in the coming weeks.

Health Secretary Wes Streeting said while the NHS was busy, there were some encouraging signs with hospital bed occupancy and ambulance delays lower than this time last year.

But he said: “We still face intense pressures and with this bitingly cold snap adding additional challenges it is more vital than ever those eligible get their flu jab and people only attend A&E in an emergency.”