The NHS is braced for the worst flu season in its history, amid fears that overcrowded hospitals will be unable to cope. The head of the health service has warned that “pressures are going to be real” as he warned that influenza levels are expected to be high.

Simon Stevens said Australia and New Zealand - who are just coming out of their winter - have had a “heavy flu season” with many hospitals struggling to deal with demand.

And he said scientists would now re-examine the vaccines amid fears that the current jabs may not hold off the infections.

Health service regulators have already warned that hospitals are extremely busy, with too many beds blocked for lack of social care.

In recent years, the NHS has seen ever long waits over winter, with some of the worst waiting times on record last winter.

However, for almost a decade the NHS has escaped a heavy flu season, with the last pandemic seen in 2009.

Mr Stevens told a conference in Manchester: "For the next three, four, five months the top priority for every leader, every part of the NHS is ensuring that the NHS goes into winter in a strong a position as possible.