US researchers flag more deadly mutation in Gamma Covid variant

A mutation in the Gamma variant (P1) of coronavirus disease is linked to increased mortality, a Harvard T.H. Chan School of Public Health and MIT researchers said on Wednesday.

The mutation also carries greater transmissibility, higher infection rates, and increased pathogenicity, showed the study detailed in the journal Genetic Epidemiology.

The findings were based on genome-wide association studies (GWAS) methodology which analysed whole-genome sequencing data of SARS-CoV-2 mutations and Covid-19 mortality data. In September 2020, the team looked for links between each mutation of the SARS-CoV-2 virus's single-stranded RNA and mortality in 7,548 Covid-19 patients in Brazil.

The researchers found one mutation -- at locus 25,088bp in the virus's genome -- that alters the spike protein and was linked to a significant increase in mortality in Covid-19 patients. The team flagged the variant with this mutation, which was later identified as part of P1.

"Based on our experience, GWAS methodology might provide suitable tools that could be used to analyse potential links between mutations at specific locations in viral genomes and disease outcome," said Christoph Lange, Professor of biostatistics at Harvard Chan School.

"This could enable better real-time detection of novel, deleterious variants/new viral strains in pandemics," Lange added.

The first patients in Brazil with the P1 variant were documented in January 2021 and within a few weeks the variant caused a spike in cases in Manaus, Brazil. The city had already been hard hit by the pandemic in May 2020, and researchers thought that the city's residents had achieved population immunity because so many people in the area had developed antibodies for the virus during that initial wave.

Instead, P1, which has several mutations in the spike protein the virus uses to attach to and invade a host cell, caused a second wave of infections and seemed to have higher transmissibility and be more likely to cause death than the earlier variants seen in the area.

Brazil has recently surpassed half a million Covid-19 deaths. With the national death toll reaching 5,00,800, Brazil has become the second country in the world to record more than half a million pandemic deaths, after the US.