The Chinese mainland has administered more than 1.7 billion doses of novel coronavirus vaccines as of Tuesday, according to the National Health Commission.

The commission said on Wednesday that the top priority of epidemic control is to resolutely prevent imported cases and focus on key sites.

Experts have reminded the public that the Delta variant of novel coronavirus is highly infectious, and data shows existing vaccines are effective on the variant.

The public is advised to reduce gatherings, wash hands frequently, wear masks, postpone trips to high- and medium-risk areas, and strictly implement various prevention and control measures.