LONDON — Britain’s top medical advisers warned the public Monday they must make further sacrifices to control the second wave of the COVID-19 pandemic, saying new coronavirus infections could increase tenfold to almost 50,000 a day next month if nothing is done now to stem the tide.

In a briefing televised live to the nation, Chief Scientific Officer Patrick Vallance and Chief Medical Officer Chris Whitty said after a slow rise in new infections over the summer, the number of new COVID-19 cases is now doubling every seven days.

In other countries, such an increase in infections has soon led to a rise in deaths, Whitty said.

“We have, in a very bad sense, literally turned a corner” after weeks of rising infections, he said.

The stark scenario lays the groundwork for the British government to announce new coronavirus restrictions. Prime Minister Boris Johnson will update lawmakers on his plans Tuesday amid increasing expectations that he will announce a slate of short-term restrictions to act as a “circuit breaker” to slow the spread of the disease.

Whitty stressed that infection rates are rising among all age groups and said it is not acceptable for individuals to ignore health guidelines and engage in risky activity. He said everyone must do their part to slow the spread of the disease because infections among the young and healthy will inevitably spread to their friends and family members and ultimately to the most vulnerable in society.

“This is not someone else’s problem,” he said. “This is all of our problem.’’

Britain already has Europe’s highest death toll in the pandemic, with over 41,800 deaths, according to a tally by Johns Hopkins University. Experts say all such figures understate the true impact of the pandemic, due to limited testing and other factors.

These Numbers Include Only Deaths That Are Directly Related to COVID-19

The British government is hoping to slow the spread of COVID-19, which last week pushed new cases to levels not seen since early May. Almost 3,900 new infections were reported on Sunday, compared with a peak of 6,199 cases on April 5.

While death rates have remained relatively low so far, Whitty warned that deaths are likely to rise in coming weeks. The U.K. reported a seven-day average of 21 deaths a day last week, compared with a peak of 942 on April 10.

These numbers include only deaths that are directly related to COVID-19. The real toll could be much higher if emergency services are overwhelmed by coronavirus cases and the National Health Service has to divert resources from treating other diseases, Whitty said.

But Whitty said this has to be balanced against the impact on the economy and society from measures to control the virus, because increased deprivation and mental illness will also lead to deaths.

“Ministers making decisions — and all of society — have to walk this very difficult balance. If we do too little, this virus will go out of control and you will get significant numbers of increased direct and indirect deaths,’’ he said “But if we go too far the other way, then we can cause damage to the economy, which can feed through to unemployment, to poverty, to deprivation.”

Vallance said efforts to find a vaccine are continuing and while it is still not clear they will work, t here is increasing evidence the research is pointing in the right direction. He said some vaccine could be available by the end of the year “in small amounts for certain groups.”

The government last week stopped short of imposing a total lockdown in northeastern England, where the infection rate first began to rise. Instead, bars and restaurants were ordered to close between 10 p.m. and 5 a.m. and people were prohibited from socializing with other households.

An Effective Testing Program Is Seen as Essential to Controlling the Pandemic

Lockdown fears hit stocks on Monday as shares in companies in aviation, hospitality and travel took a beating. Shares in IAG, the parent company of British Airways, fell 11.3%, while pub company Mitchells & Butlers fell 11% and Intercontinental Hotels Group fell 4%.

Dr Michael Head, a global health expert at the University of Southampton, noted that Monday’s warning highlighted the worst possible situation and did not take into account measures like local lockdowns that could stem the spread of the virus.

“It is important to note that the chief medical (officer) did say the potential for 50k cases a day is a ‘worst-case scenario’,” he said, but he added that “it’s a timely reminder that the pandemic is accelerating, both globally and also here in the UK.”

The rise in U.K. infection rates comes as lawmakers across the political spectrum have criticized the Conservative government’s testing program as inadequate. While government ministers tout the record numbers of tests being performed, there are widespread reports of people having to travel hundreds of miles for tests or tests being voided because it’s taking labs too long to process them.

An effective testing program is seen as essential to controlling the pandemic because it allows the government to track infections and inform people when they should self-isolate. An app meant to bolster such efforts is set to be released this week after months of delay.

In hopes of persuading people to stay home, the government announced Monday it would pay low-income people 500 pounds ($639) if they are asked to self-isolate for 14 days. It also warned those breaking quarantines of possible fines that could run into thousands of pounds (dollars).