Coronavirus disease 2019 (COVID-19) has caused more than five million deaths and has spread to almost every country in the world. The economic crisis was caused by the strict restrictions imposed by governments to stop the spread of the disease. These included social distancing and closing public spaces.
Mass vaccination programs have enabled several countries to be more open however, many countries in the developing world are still struggling and new variants are constantly appearing. These variants of concern (VOCs) that can be evaded both through vaccination and natural respiratory syndrome coronavirus 2 (SARS-2 CoV-2) have a number of troubling characteristics.
Now, researchers from Public Health Services Israel have been looking into a brand new variant called Lambda to determine whether it’s a variant of concern. Their findings were published in the journal EUROsurveillance.
A number of COVID-19 cases involving the Lambda variant (red), in Israel between April until June 2021 in Israel. One case was identified from April 1-15 4 between April 16-31 and 12 between May 1-15, 12 between May 1-15, and one between June 16 and 31. The Alpha variant (yellow) dropped to just 50 cases at the beginning of June, whereas the Delta variant (blue) rapidly grew to 1,655 cases by June’s end.
Like other variants of the Lambda variant, this one is identified by mutations in spike proteins. This includes 75V, T76I and F490S, L452Q, D246-252 and. The spike protein is essential to the pathogenesis of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is a trimeric surface protein that is composed of two subunits . It must be cleaved with an host protein (S1 or S2).
S1 contains a receptor-binding domain (RBD) that can bind to angiotensin-converting enzyme 2 (ACE2) among other receptors in order to permit viral cell entry. S2 is responsible for membrane fusion. Many mutations that create new forms alter homotrimers’ conformation – each monomer has the option of facing ‘up’ (or down) which can result in four possible conformations: up-up-up, down-down–down, up–up-down-down, and down-down–down.
The proteins that face down are less likely to trigger an immune response. This is the evolutionary method that wild-type SARS-CoV-2 attempted to use. The protein that faces up shows an increase in ACE2 binding and is much more infective – this is often observed in variants. Unfortunately these modifications in conformation also make many vaccines less efficient.
The researchers studied the neutralization of the Lambda variant in the sera of 36 people between the ages of 27 and the age of 66, and most were women. All had received two doses the Comirnaty vaccine, and the second dose was administered at least one month prior to testing.
The neutralizing titers of Lambda were compared to wild-type (WT), Alpha variant, and the Delta variant. Virus samples were characterized via whole-genome sequencing. Double-diluted sera inactivated were added to suspensions of virus containing an infective dose for each SARS/CoV-2 variant/WT. They were then placed on 96 well plates and incubated for 60 minutes at 33C. Vero-E6 cells were incubated for 5 days with the mixture of virus serum prior to Gentian violet staining was applied to the layer of cells.
The mean neutralizing titer against WT was 103.6 and against Lambda was 66.5 The titer against Alpha was 90.5, and against Delta was 57. To demonstrate significant differences between WT and all variants except Alpha, the researchers used Wilcoxon signed-rank tests.
While the Lambda variant is currently only classified as a variant under investigation (VOI) and is not a VOC, it has spread to over 30 countries and is particularly endemic in South America.
As the Comirnaty vaccine has been found to be 95% effective in preventing symptomatic COVID-19 caused by WT and Alpha variant of SARS-CoV-2. The increasing spread of the Lambda variant in Israel may be due to the high vaccination rate of 80 percent in June 2021. The massive vaccination might have enabled the Alpha variant to spread more easily than other variants, since it was the most common cause of new cases in the country.
The findings of the researchers are supported by several other studies that show significant reductions in of neutralizing titer and effectiveness against newly developed variants.
While the study was small, the authors draw attention to the risk of the Lambda variant to infect people who have been fully vaccinated and call for mass vaccination to be employed alongside other measures to reduce the spread of the disease, for example, social distancing measures and wearing masks.
Content Source: https://www.news-medical.net/news/20211116/How-effective-is-the-COMIRNATY-BNT162b2-vaccine-against-the-SARS-CoV-2-Lambda-variant.aspx