GENEVA, April 13 (Xinhua) -- World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus warned here on Monday that the COVID-19 pandemic accelerates fast but decelerates much more slowly.

"In other words, the way down is much slower than the way up," he told a press briefing.

Tedros stressed that control measures must be lifted slowly and it cannot happen all at once.

"Control measures can only be lifted if the right public health measures are in place, including significant capacity for contact tracing," he said.

Some European countries are considering relaxing their restriction measures as they see a slowing trend in the number of COVID-19 infections. Austria, for instance, aims to gradually ease the exit restrictions and reopen shops and businesses from mid-April. Switzerland also suggested "the first relaxations" by the end of April.