Explained: Why the mutated coronavirus variants are so worrisome

Insufficient surveillance in most countries has obscured recognition of variants circulating in many places

Viruses mutate all the time, including the coronavirus that’s caused the Covid-19 pandemic. Although most changes are innocuous, several mutants have sparked alarm.
 
What are the most worrisome variants?
 
The World Health Organisation (WHO) uses the term “var­i­ants of concern” to signify st­rains that pose ad­d­­itional risks to public health, and “emerging variants of interest” for those that warrant cl­ose monitoring be­cause of their potential risk. These have been assigned names or codes by the various research gro­u­ps and public hea­lth agencies investigating them. As of May 11, the WHO has identified four variants of concern and six