The next few weeks will be "the worst" of the pandemic for the National Health Service (NHS), he told the BBC, urging the public to minimize all unnecessary contact with others.
"There's a very high chance that if you meet someone unnecessarily they will have Covid," he said on Monday, noting that any unnecessary contact could be a potential link in a chain of transmission that will lead to a vulnerable person, Xinhua news agency reported.
According to Whitty, there were more than 30,000 people in hospitals in England alone with Covid-19, compared to about 18,000 at the peak last April.
"Anybody who is not shocked" by the number of people in hospital "has not understood this at all," he said.
"This is an appalling situation," he added.
Another 54,940 people in Britain have tested positive for Covid-19, bringing the total number of coronavirus cases in the country to 3,072,349, according to official figures released Sunday.
Another 563 have died within 28 days of a positive test, bringing the total number of coronavirus-related deaths in Britain to 81,431, the data showed.
British Health Secretary Matt Hancock on Sunday warned that flexing the lockdown rules "could be fatal," urging the public to stay at home amid surging coronavirus infections.
"Every time you try to flex the rules that could be fatal" and staying at home was the "most important thing we can do collectively as a society," Hancock said.