As the coronavirus disease (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), wreaks havoc across the globe, the efficacy of available vaccines is being threatened by emerging variants.
Several new variants have been identified, which may cause severe illness in some people and are more transmissible. The World Health Organization (WHO) recently classified the lambda variant as a " Variant of Interest."
The WHO describes a Variant of Interest (VOI) as having genetic changes predicted or known to affect virus characteristics such as transmissibility, disease severity, immune escape, diagnostic or therapeutic escape.
In a report posted to the pre-print server medRxiv, researchers recently discussed the emergence of a novel lineage of SARS-CoV-2 in South America.
Transmission electron micrograph of SARS-CoV-2 virus particles. Image Credit: NIAID
Where did the lambda variant come from?
First detected in Lima, Peru, in December 2020, the variant accounted for 97% of all sequences in Peru by April 2021. The variant has spread to neighboring countries like Chile, Argentina, Colombia, Ecuador, Mexico, the United States, Israel, Germany, and even Australia.
The most concerning news about the lambda variant is it has dominated new infections in Peru, a country with the highest number of COVID-19 deaths per capita. For every 100,000 of the country's population, 596 have died of the infection. Overall, Peru has lost nearly 195,000 people to COVID-19 among its population of over 32 million, which is about three times the rate of U.S. deaths per capita.
With more than 2 million reported infections to date, Peru has been hit by the coronavirus pandemic. The country continues to fight the global health crisis despite a limited healthcare capacity, a slow vaccine rollout, and outdated intensive care units (ICUs).
Because of these factors, the lambda variant spread throughout the country and other regions—the WHO reported that the variant had been detected in 29 countries with increasing prevalence.
Like other variants, the lambda variant has mutations that increase transmissibility. In addition, evidence suggests that the variant affects how fast the infection spreads, the severity of the illness, and the ability to evade immunity to natural infection or vaccination.
Also called the C.37 variant, it presents with seven nonsynonymous mutations in the Spike (S) gene, including G75V, T76I, D614G, L452Q, F490S, T859N. In addition, the variant has a deletion in the ORF1a gene, Δ3675-3677, which is also found in other variants of concern (VOCs) Alpha, Beta, and Gamma.
The mutations L452Q and F490S map to the Spike protein's receptor-binding domain (RBD), the part of the coronavirus that binds to the human angiotensin-converting enzyme 2 (hACE 2) receptor to invade the cells. Though L452Q is almost exclusive to C.37, L452R is present in the currently dreaded B.1.617.2 or Delta variant, and the variants of interest Epsilon (B.1.427/B.1.429) and Kappa (B.1.617.1). The L452R is also linked to reduced in vitro susceptibility to antibody neutralization.
These mutations within the RBD may contribute to its increased transmissibility and could result in susceptibility to re-infection or a reduction in the protection provided by current vaccines.
Since the lambda variant is novel, there is limited data on how it can affect the current pandemic trends. A study that appeared in the pre-print server bioRxiv showed how the lambda spike protein contains novel mutations within the RBD that increase transmissibility.
When the researchers examined the infectivity and susceptibility of viruses with the lambda variant spike protein to neutralization by vaccine-induced antibodies or convalescent sera, they revealed that the lambda variant exhibited higher infectivity and was neutralized with a moderately minor 2.3 to 3.3-fold decrease in titer. This means that the current vaccines and convalescent sera are potentially effective in protecting against this VOC.
To date, there are over 188 million cases of COVID-19 since it first emerged in December 2020. Of these, more than 4 million people have already died. The United States reports the highest COVID-19 cases, topping 33.94 million cases, followed by India and Brazil, with 30.94 million and 19.2 million cases, respectively.
- Romero, P., Davila-Barclay, A., Salvatierra, G., et al. (2021). The Emergence of SARS-CoV-2 Variant Lambda (C.37) in South America. medRxiv. https://www.medrxiv.org/content/10.1101/2021.06.26.21259487v1
- Tada, T., Zhou, H., Dcosta, B., Samanovic, M., Mulligan, M., and Landau, N. (2021). SARS-CoV-2 Lambda Variant Remains Susceptible to Neutralization by mRNA Vaccine-elicited Antibodies and Convalescent Serum. bioRxiv. https://www.biorxiv.org/content/10.1101/2021.07.02.450959v1?rss=1%22
- Robertson, Sally. (2021, June 27). Lambda lineage of SARS-CoV-2 has potential to become variant of concern. News-Medical. Retrieved on July 15, 2021 from https://www.news-medical.net/news/20210627/Lambda-lineage-of-SARS-CoV-2-has-potential-to-become-variant-of-concern.aspx.
- Meštrović, Tomislav. (2021, July 08). Growing concern over SARS-CoV-2 Lambda variant. News-Medical. Retrieved on July 15, 2021 from https://www.news-medical.net/news/20210708/Growing-concern-over-SARS-CoV-2-Lambda-variant.aspx.
- Solis-Moreira, Jocelyn. (2021, July 07). SARS-CoV-2 Lambda variant spreading rapidly in South America, report reveals. News-Medical. Retrieved on July 15, 2021 from https://www.news-medical.net/news/20210707/SARS-CoV-2-Lambda-variant-spreading-rapidly-in-South-America-report-reveals.aspx.