The Omicron COVID-19 variant is in now in at least 38 countries, and scientists are still trying to figure out how effective vaccines are against it.
Several European countries are tightening restrictions as coronavirus cases surge across the continent.
In Brussels, Belgium those restrictions prompted large protests.
Police used water cannons and tear gas to try and control violent protesters.
On Friday alone, more than 1,500 Europeans died from COVID-19.
The surge moving through Europe and many other parts of the world is thought to be fueled by the omicron variant, first detected in South Africa.
Infections around Johannesburg tripled in just three days last week, raising fears that the Omicron variant is more transmissible than others.