If for the world the most recent threat linked to Covid-19 is the delta variant, in South America the attention is turning to a much less known strain: the lambda.
First identified in August last year in Peru, lambda was classified in mid-June as a variant of interest, meaning it needs to be studied and monitored.
According to the WHO (World Health Organization), the strain was associated with high rates of community transmission in several countries, while there was also an increase in the incidence of Covid-19 in these places.
The same agency report says more than 1,730 lambda sequences from 31 countries, territories and areas have been sent to Gisaid, a platform that compiles genomic data.
Although it is not at the top of the strains considered to be the most dangerous, classified as variants of concern by the WHO (alpha, beta, gamma and delta cases), lambda is gaining ground in South America, where its incidence is important.
“To be a variant of the marigold, you have to have a significant community circulation, and at the moment [a lambda] they don’t have one, ”explains Jamal Suleiman, an infectious disease specialist at Emílio Ribas Hospital.
He also states that, to be a variant of concern, lambda would have to differ from other circulating mutations, such as a greater capacity for infection, which would increase its spread among people, greater severity of the disease, or even diseases. clinical features that compromise other areas of the person who is infected, such as skin or neurological presentations different from what has been observed in other strains.
The country with the greatest presence of lambda so far is, proportionally, Peru, with an incidence of 40% in the cumulation – that is to say since the first time that the strain was identified in the country. . From April to June, authorities said 81% of Covid-19 cases in the country were of this variant.
Chile (21%), Ecuador (11%) and El Salvador (3%) are next, according to data from Outbreak Info, an initiative that compiles genomic information from Gisaid, collected in 172 countries.
“In Argentina, at one point, the lambda reached a third [das infecções] in the Buenos Aires metropolitan area, ”explains Fernando Spilki, coordinator of Rede Corona-ômica BR-MCTI, a laboratory project that sequences the genomes of Sars-Cov-2 samples in Brazil.
The WHO report also showed that, since the third week of February 2021, the presence of lambda in Argentina has increased.
In a recent report from the Peruvian Ministry of Health, published last Wednesday (18), lambda represented more than half (54.7%) of the samples analyzed, followed by gamma (15.9%), initially identified in Brazil.
This combination could signify a difficult scenario, as the coordinator of the Laboratory of Microbial Genomics in Peru, Pablo Tsukayama, warned in an interview with BBC News Mundo. “Countries that had these two variants went from a bad situation to an uncontrolled situation, with second waves much more severe.”
But for Spilki, the peak of lambda transmission in countries like Peru and Argentina was from April to July of this year, and currently the rate of infection with this variant is declining and there is evidence of ‘an increase in the number of cases per delta.
Delta, originally identified in India, is only linked to 1.9% of cases in Peru. Despite this, the minister of the ministry, Hernando Cevallos, warned last week against the presence of this variant. “It is important that we realize this. We are facing a strong possibility of having triggered the third wave in our country ”, he declared, according to the newspaper El Comercio.
Falling until the end of July, the moving average of cases in Peru rose earlier this month, before falling back in recent days. As of Sunday (22), the rate was 1,191 new infections. The moving average of deaths is coming at the same rate, and the index reached 69 on the same day.
The figures are far from the peak of 874 deaths and nearly ten thousand cases recorded in April of this year, but the emergence of variants is a further obstacle to the progress of the pandemic.
In the case of lambda, the WHO has pointed out that the mutations present may mean greater transmissibility and increased resistance to neutralizing antibodies, an aspect related to the effectiveness of immunizing agents. The organization warned, however, that more studies were needed to understand these points.
A survey released earlier this month in turn confirmed WHO’s fears that lambda is more transmissible and resistant to vaccines. The study of Japanese researchers still depends on peer validation.
For biomedical scientist Mellanie Fontes-Dutra, coordinator of the Covid-19 analysis network, it is important to note that, despite this resistance, the vaccines tested so far have shown that they retain some protection, especially in severe cases. “It’s a variant that you have to watch out for,” he says. “But it doesn’t look like something like the Delta, so it’s unlikely to gain much space.”
Dutra also points out that the crux of the matter is transmission, as the variants compete against each other within the same environment, with the most appropriate becoming predominant.
“We know that it is because of the acceleration of the transmission that the risk of emergence of new variants increases. To get around this situation and out of the pandemic, we must consolidate our path, with mass vaccination and non-pharmacological control measures, such as mask use and physical distancing. “
In the Brazilian context, Fernando Spilki declares that the lambda has never equaled the situation of the delta or the gamma, another variant which continues to be of great importance in the country. “So far the gamma has been without a doubt the most important, now we have an escalation of the delta, but indeed the lambda that we haven’t found over time.”
According to data from the BR-MCTI Corona-Omic Network, as of August 18, 2021, there were 29,447 genomes sequenced in the country. Of these, only 6 were lambda, while delta had 79 and gamma 17,507.
“As there are few cases of lambda, we cannot yet draw any conclusions [sobre os efeitos das alterações nessa variante]», Explains Luiz Henrique Nali, doctor in tropical medicine with specialization in virology at USP and professor at the University of Santo Amaro.
He explains that Brazil has little capacity to track the variants circulating in the country and, without this data, it is difficult to understand the specific behavior of each of them.