The UK government imposed a strict lockdown in London and other cities in the United Kingdom over the weekend after reports of a SARS-CoV-2 mutation that is more virulent and more transmissible. Nations in the EU like France and Italy have banned all travel to and from the UK in hopes of preventing the strain from taking a hold on the European continent.

The variation found in the UK, known as “VUI – 202012/01” was first identified there in mid-September, according to the World Health Organization. Its mutations have occurred on the genetic material that controls the spike protein, which allows COVID and other similar viruses to penetrate host cells, causing infection.

According to the UK’s chief scientific adviser, Patrick Vallance, there are 23 changes in the virus’s genetic material, an unusually large number that appears to be helping it spread more quickly. British officials have now estimated that “VUI – 202012/01” is as much as 70 percent more transmissible — a number that is based on modeling, but not yet confirmed in lab experiments.