A strain of influenza known as Australian flu is contributing to the NHS’s winter pressures this year.
The arrival of so-called Aussie flu comes as NHS England urged hospitals to defer pre-planned operations and routine outpatient appointments until the end of the month.
As well as higher levels of flu, the norovirus is also causing problems for hospitals.
Here are the key questions and answers about the illnesses.
What is Australian flu?
There are two main types of flu - A and B.
One of the strains of influenza circulating the UK this year is a type of A flu known as H3N2.
Why is it called Australian flu?
The particular strain of H3N2 flu that is affecting the UK is similar to the type that Australia suffered from earlier this year, during their winter.
Dr Richard Pebody, acting head of respiratory diseases at Public Health England, said: “In Australia they saw excess mortality and other hospitalisations and so on due to H3N2.”
What are the symptoms?
Dr Pebody said the H3N2 influenza can cause problems for the elderly, and can particularly result in care home outbreaks.
High fever, aches and pains and feeling tired are common symptoms of the flu, as is a dry cough, a sore throat and a headache.
Will the flu vaccine help?
Dr Pebody said the flu vaccine is currently the best preventative for flu.
He said that while the effectiveness data for this year’s flu is not yet available, he hopes the vaccine will provide “reasonable protection” against Australian flu.
While it takes 10 to 14 days for the vaccine to take effect, Dr Pebody encouraged those who can take advantage of the NHS’s free programme, which includes anyone who is pregnant or over the age of 65, to do so.
What about the norovirus?
The norovirus, which causes diarrhoea and vomiting, is one of the UK’s most common stomach bugs.
It is more prevalent in the winter, with levels of the illness contributing to current NHS pressures.