Health authorities have stepped up anti-infection measures in Bulgaria's capital, Sofia, and other major cities in response to a surge in new coronavirus cases driven by the highly contagious Omicron variant, reports AP.

Schools are limiting in-person classes, requiring students in all grades except first through fourth to switch to distance learning.

The precautions also ban mass events and require restaurants and bars to operate at half of their customer capacity. All catering and entertainment establishments have to close no later than 10pm, and visitors need valid health certificates to be admitted.