The World Health Organization says new coronavirus variants have rapidly replaced the original strain in the United Kingdom, South Africa and Brazil.
A WHO report dated on Tuesday says new variant infections have spread rapidly in the UK and South Africa since last October, accounting for most of the cases detected in those countries. It also says the proportion of new variant cases amounts to about half of the infections in Brazil.
The report says the additive increase in the effective reproduction number relative to the wild-type variant was estimated at 41 percent for the variant first detected in the UK, 36 percent for the South Africa variant, and 11 percent for the Brazil variant. The effective reproduction number indicates the average number of people a single virus carrier will infect.
The report says the UK variant has been detected in seven additional countries over the week and a total of 125 countries have reported cases of the variant.
It says the number of countries that have reported cases of the South Africa variant increased by 11 over the week to 75. The figure rose by 3 to 41 for the Brazil variant.
The WHO is stepping up its monitoring of the three variants, designating them as "variants of concern."
The latest report lists two more variants as "variants of interest."
New coronavirus cases reported around the world in the week through Sunday rose for a fourth straight week partly because of increases in Brazil, India and France. The number of new deaths in the week was also up, after a six-week decline.