The coronavirus pandemic is being driven by people in their 20s, 30s, and 40s who don't know they're infected, according to WHO

• The novel coronavirus is being spread largely by younger people, many of whom are unaware they are infected, according to the World Health Organization.
• "People in their 20s, 30s, and 40s are increasingly driving the spread. Many are unaware they are infected. This increases the risk of spillovers to the more vulnerable," a WHO official said Tuesday.
• Many European countries have recorded a sharp uptick in coronavirus cases in recent weeks as social-distancing measures were relaxed and national lockdowns were eased.

The coronavirus is being spread largely by younger people, many of whom are unaware they are infected, according to the World Health Organization.

WHO officials said on Tuesday that the proportion of young people infected with the virus had risen and continued to rise and that they were putting elderly people and other vulnerable groups at risk.

"The epidemic is changing," WHO's Western Pacific regional director, Takeshi Kasai, said at a virtual briefing in comments reported by Reuters.

"People in their 20s, 30s, and 40s are increasingly driving the spread," he said. "Many are unaware they are infected. This increases the risk of spillovers to the more vulnerable."

At-risk groups include elderly people and those with preexisting health conditions.

Many European countries have recorded sharp upticks in coronavirus cases in recent weeks as social-distancing measures were relaxed and national lockdowns were eased.

Greece, Croatia, and Turkey could become the latest countries to be added to the UK's quarantine list, according to a Sky report, as they have recorded upticks in COVID-19 cases.

The move would require British holidaymakers to quarantine for 14 days when they return from the countries. Countries that have been added to the UK's quarantine list in recent weeks include France, Spain, Belgium, and the Netherlands.

Amid the threat of such travel restrictions, WHO Director-General Tedros Adhanom Ghebreyesus said last week that countries should try to address the pandemic by suppressing the virus, as countries such as Vietnam and New Zealand have done with relatively high success.

"My message is crystal clear: Suppress, suppress, suppress the virus," he said in comments reported by the news website The Independent.

"If we suppress the virus effectively, we can safely open up societies."