Global coronavirus cases have hit 40 million, doubling since August 10

• The known global coronavirus case count hit 40 million on Monday.
• Large parts of the world are seeing infections surge, and governments are scrambling to institute new restrictions.
• The US, India, and Brazil remain the hardest-hit countries, with a combined 21 million reported cases.

The number of known global coronavirus cases reached 40 million on Monday, as much of the world heads into a new wave of the outbreak.

That figure is based on three different estimates — from Reuters, Worldometer, and Johns Hopkins University. The real figure is probably much higher too, experts have said.

Monday's landmark figure marks a doubling of the worldwide coronavirus case count since August 10, and it comes three days after global cases rose by a record 400,000 in one day, according to Reuters.

The US, India, and Brazil have reported the most cases in the world, combining for nearly 21 million.

Europe appears to be emerging as a new epicenter of the virus. On Friday, the continent reported more new cases than the US, India, and Brazil combined, according to Reuters.

European governments are also scrambling to impose new restrictions to protect hospitals from running out of beds.

Even Sweden, which took a unique approach at the beginning of the pandemic by not closing schools or businesses, is now working on imposing restrictions for the first time amid a concerning rise in deaths.

As of Friday, France had the highest seven-day average of cases in Europe, recording nearly 20,000 infections a day, according to Reuters.

In the UK, Prime Minister Boris Johnson unveiled a new three-tier lockdown system for England last week. Within days, the capital of London was put into the middle tier, with households no longer allowed to mix indoors. Liverpool is under the highest warning, with pubs and bars ordered to close.

Since the beginning of the pandemic, experts have warned that a second, more deadly wave could begin in the fall when people started spending more time indoors, as happened during the 1918 flu pandemic.

Dr. Michael Osterholm, a top infectious-disease expert, told NBC News on Sunday that "the next six to 12 weeks are going to be the darkest of the entire pandemic."

The coronavirus appears to be turning less fatal, however, as the pandemic wears on and doctors get better at treating COVID-19.

Spain, for example, has seen infections rise steadily since July. During this new wave, however, its highest daily death count has been 380, recorded September 30 — which is much lower than the first-wave high of 961 deaths, recorded April 20.

The world is also getting closer to finding an effective coronavirus vaccine.

Multiple drug companies are thought to be nearing the end of their clinical trials, with the two of the most promising vaccines being developed by Pfizer and Moderna.

Pfizer recently said it's preparing to send its vaccine to the US Food and Drug Administration for approval by the end of November. UK officials said they were preparing for a vaccine to be ready shortly after Christmas.

Disbursing a vaccine could take some time, though. Dr. Soumya Swaminathan, the chief scientist at the World Health Organization, said last week that young people might have to wait until 2022 to receive a vaccine so that more vulnerable people in the population could get it first.