COVID-19 infections rose by 8 percent last week to more than 3.8 million, the World Health Organization (WHO) said on Wednesday.

For the past week, the global number of new cases rose by 8 percent compared with the previous week, which was largely attributed to substantial increases in the Americas and the Western Pacific Regions, the WHO said in its weekly update report.

Of the four COVID-19 mutations that WHO has designated "variants of concern," the WHO said that the Alpha variant is present in 182 countries and regions, Beta is in 131, Gamma in 81 and after reaching eight new countries and regions in the past week, the Delta variant is now in 132 countries and regions.