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Lambda, the latest variant of the coronavirus that catches the attention of the World Health Organization, worries Latin American officials and baffles scientists because of its set of “unusual” mutations.
Formerly known as C.37, the Lambda variant was first detected late last year in Peru and has since spread to 27 countries, including the United Kingdom. Public Health England this week said it had been identified “nationwide,” although the number of cases it had identified remained small.
Pablo Tsukayama, a doctor in molecular microbiology at Cayetano Heredia University in the Peruvian capital Lima, said that when doctors first pointed out the variant in December, they represented only one in 200 samples.
“In March, however, it accounted for about 50% of the samples in Lima and is now 80%. This would suggest that its transmission speed is higher than other variants,” he said.
According to the WHO, Lambda accounted for 82% of new cases of Covid-19 in May and June in Peru, the highest coronavirus mortality rate in the world. In neighboring Chile, it accounts for almost a third of new cases.
However, scientists still do not know if Lambda mutations make it more transmissible.
“At the moment there is no evidence to suggest that it is more aggressive than other variants,” said Jairo Méndez Rico, an advisor for emerging viral diseases at the Pan American Health Organization. “You may have a higher infection rate, but you need to work harder on it.”
In June, the WHO named Lambda as the seventh “variant of interest” to date. The global health agency believes these strains are less of a threat than its four “variants of concern” (Alpha, Beta, Gamma and Delta originally detected in the UK, South Africa, Brazil and India respectively), but says which have yet to be controlled. up close.
One week later, on 23 June, PHE in the UK designated Lambda as a variant investigated “due to international expansion and several notable mutations”. PHE stressed that there is currently no evidence that Lambda caused more serious illnesses or that vaccines were less effective.
“One of the reasons it’s hard to make sense of the Lambda threat, using computer and lab data, is that it has an unusual set of mutations, compared to other variants,” said Jeff Barrett, director of the Covid-19 Genomics Initiative at the Wellcome Sanger Institute in the UK.
Barrett added that the lack of genetic sequencing facilities in Latin America had made it difficult to know to what extent Lambda was driving Covid-19 outbreaks in the region.
Lambda has a unique pattern of seven mutations in the spike protein that the virus uses to infect human cells. Researchers are particularly fascinated by a mutation called L452Q, which is similar to the L452R mutation that is believed to contribute to the high infectivity of the Delta variant.
Monica Acevedo and colleagues at the University of Chile, Santiago, studied the effect of Lambda on viral infectivity using blood samples from local health workers who had received two doses of China’s CoronaVac vaccine.
Their results, published in prepress paper on Thursday, you suggest that Lambda is more infectious than Gamma and Alpha and is better able to escape the antibodies produced by vaccination. “Our data show for the first time that mutations present in the Lambda variant spike protein confer leaks to neutralizing antibodies and increase infectivity,” they wrote.
In Brazil, where the Gamma variant has caused infections so far, a team of researchers at a hospital in the southern city of Porto Alegre analyzed a patient infected with Lambda. “Given that this variant has spread rapidly to Peru, Ecuador, Chile and Argentina, we believe that Lambda has considerable potential to become a variant of concern,” they concluded in a prepress paper, which has not been peer reviewed.
Latin America has been the region of the world most affected by the pandemic. With only 8% of the world’s population, it accounts for 20% of coronavirus cases. In recent weeks, Colombia, Paraguay and Uruguay have seen an increase in the number of cases.
“While we see some recovery from the virus in northern hemisphere countries, for most countries in our region the end is still a distant future,” PAHO Director Carissa Etienne said this week.
Cases continue to rise in countries such as Colombia, Brazil, Bolivia and Uruguay, said Etienne, who added that hospitals were struggling to expand intensive care units.
“Despite this worrying picture, only one in ten people in Latin America and the Caribbean has been completely vaccinated against Covid-19, an unacceptable situation,” he said.
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