A COVID-19 variant believed to be behind the one of the pandemic's deadliest waves of death to date is getting a foothold in other countries, scientists have warned.
The Lambda variant was first detected in Peru, according to the World Health Organization (WHO), and has since spread to at least 29 others - including the US, Germany and the UK, which have all moved towards lifting restrictions in recent weeks.
There are fears Lambda is even more infectious than the Delta and Alpha variants, which have caused widespread disease and misery in India and the UK, respectively.
Since it emerged in December, Lambda has fast risen to become the dominant strain in Peru - accounting for 82 percent of new cases in June, according to Cayetano Heredia University Professor Pablo Tsukayama - up from just 200 known cases six months ago.
"That would suggest its rate of transmission is higher than any other variant," he told the Daily Telegraph.
Peru has one of the world's worst mortality rates from the SARS-CoV-2 virus, which causes COVID-19. The country of 32 million people has recorded just over 193,000 deaths from its 2 million confirmed cases - a case fatality ratio (CFR) of 9.4 percent according to Johns Hopkins University's Coronavirus Resource Centre.
At the height of the recent wave, Peru was losing more than 1000 lives a day - per capita, that would be the same as New Zealand losing about 150 a day.
While it's believed many cases of COVID-19 around the world have gone unreported, Peru's CFR is second only to war-torn Yemen. In comparison, the CFR for New Zealand is just 0.9 percent. The United Kingdom, hit hard by the Alpha variant, has a CFR of 2.6 percent. India, where Delta emerged, has a CFR of 1.3 percent - it's believed both cases and deaths there have been vastly undercounted.
Lambda has a mutation similar to one that helps Delta infect new hosts, and six others that haven't been seen before whose effects are thus far unknown.
"One reason why it is hard to make sense of the threat from Lambda, using computational and lab data, is that it has rather an unusual set of mutations, compared with other variants," Jeff Barrett, director of the UK's COVID-19 Genomics Initiative, told the Financial Times.
According to a University of Chile paper published online last week ahead of peer review, Lambda is more infectious than Delta, which was already about 55 percent more contagious than Alpha, which in turn was 50 percent more infectious than the original Wuhan strain.
"Our data show for the first time that mutations present in the spike protein of the Lambda variant confer escape to neutralising antibodies and increased infectivity," the scientists wrote, hinting that it might also have a better ability to avoid vaccines.
"Our results indicate that mutations present in the spike protein of the Lambda variant of interest confer increased infectivity and immune escape from neutralizing antibodies elicited by CoronaVac."
That study looked at people in Chile who had been vaccinated with the Chinese-made CoronaVac vaccine, made by Sinovac. It's not yet clear if the Western-made vaccines like those from Pfizer-BioNTech, Moderna and AstraZeneca will have similar problems. While Pfizer and Moderna's mRNA vaccines appear to work almost as well against Delta, that's only after two doses - with just one, they're much weaker than they are against the original and Alpha strains.
The AstraZeneca vaccine - which has been widely in the UK - only offers 60 percent protection against Delta after two doses, a Scottish study found. The Chilean study found CoronaVac was three times less effective against Lambda than the original strain.
Lambda has been dubbed a 'variant of interest' by the WHO, a step below being a 'variant of concern'. If it's proven to be more infectious or be more deadly, it's likely to be promoted. The current variants of concern are Alpha (UK), Beta (South Africa), Gamma (Brazil) and Delta (India). Other variants of interest include Epsilon and Iota (US), Zeta (Brazil), Eta (multiple) and Theta (Philippines).