The country is at a tipping point similar to the first wave of coronavirus, but can prevent history repeating itself, England's deputy chief medical officer has said.
Professor Jonathan Van-Tam said the best way to keep transmission low and stop the NHS being overwhelmed was for people with symptoms to self-isolate and get a test, and for people to wash their hands, wear face coverings and maintain social distancing.
In a statement on Sunday, he added: "In our national fight against Covid-19, we are at a tipping point similar to where we were in March; but we can prevent history repeating itself if we all act now.
"Earlier in the year, we were fighting a semi-invisible disease, about which we had little knowledge, and it seeded in the community at great speed.
"Now we know where it is and how to tackle it – let's grasp this opportunity and prevent history from repeating itself."
Prof Van-Tam said the country had much better testing capabilities, knew more about the disease, and had better treatments than during the first wave.
But with Office for National Statistics (ONS) data showing that an estimated 224,000 people have the virus – and hospital and intensive care admissions from Covid rising – more deaths will follow, he warned.
Prof Van-Tam said the R number – the rate at which the virus is spreading from person to person – was well above one in every NHS region in England, suggesting "widespread transmission" across the country – not just the north.
Scientists estimate that the doubling time in the UK for new infections is between eight and 16 days and is even faster in some areas, he added.
Prof Van-Tam said that while during the winter months the NHS will "work their socks off" to help people, there was only so much they can do.
He said that elective surgeries and non-urgent services, cancer treatment, diagnostic and mental health services needed to keep going for as long as possible, and people need to come forward for that care when they need it.
But in order to help the NHS, people need to help keep case numbers down, he added.
He said: "If cases rise dramatically the NHS will need to focus more on dealing with the life-threatening situations immediately in front of them; this can mean freeing up staff and space by postponing other non-urgent procedures and treatments.
"We need to help the NHS by keeping Covid-19 numbers low; and in turn the NHS will be there for us, our families and loved ones.
"By keeping our contacts low we reduce the number of opportunities for the virus to spread.
"I know this is very hard, but it is an unfortunate scientific fact that the virus thrives on humans making social contact with one another."