On December 12, the World Health Organisation (WHO) said that the Omicron variant is more transmissible than the Delta strain. WHO added that the Omicron variant reduces vaccine efficacy but causes less severe symptoms as per early data. The Delta variant is responsible for most of the world's Covid-19 infections. It was first identified in India. Omicron was discovered by South Africa. Several countries across the world have imposed travel bans on southern African countries and also got back domestic restrictions. Meanwhile, on December 12, the United Kingdom raised its Covid-19 alert level due to rising cases of Omicron. Watch the video to know more.