The world is at risk of losing hard-won gains in fighting COVID-19 as the highly transmissible Delta variant spreads, the World Health Organization said on Friday.

COVID-19 infections have increased by 80% over the past four weeks in most regions of the world, WHO director-general Tedros Adhanom Ghebreyesus said. Deaths in Africa – where only 1.5% of the population is vaccinated – rose by 80% over the same period.

“Hard-won gains are in jeopardy or being lost, and health systems in many countries are being overwhelmed,” Tedros told a news conference.