The Lambda mutation, or C.37, appears to have emerged in Peru last August — and is now being blamed for the country having the highest pandemic death rate in the world. The concerning strain has since spread to around 30 countries, mostly in Latin America — but also as far as the UK, which has recorded at least eight cases, according to government figures. There are no known cases of the Lambda strain in the US, according to the Centers for Disease Control and Prevention. In Peru, Lambda has accounted for 81 percent of new infections tested for variants since April, according to the World Health Organization.