People are seen getting out of their houses as UK lifts its second national lockdown and shops, gyms and hair salons are allowed to reopen under a revised three-tier system of restrictions, in London, UK, December 2, 2020. /Getty

The revised three-tiered system includes three levels of alert: medium alert, high alert, and very high alert, and across all tiers people must wear a mask in most indoor public settings and follow rules on gathering and meetings. /Getty

London is now on high level alert. Pubs remain closed unless they serve substantial meals along with alcoholic drinks. /Getty

Due to the surge of COVID-19 cases, UK imposed a second national lockdown on November 5, 2020, during which non-essential businesses including pubs, gyms and restaurants were closed, while schools and universities stayed open. /Getty