As the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease (COVID-19), spreads globally, new emerging variants pose health threats to many counties.
The emergence of variants with specific mutations of key epitopes in the spike protein of SARS-CoV-2 raises concerns on vaccination efforts and the use of monoclonal antibodies.
Researchers at the University College London and the University College London Hospitals NHS Foundation Trust aimed to describe the emergence of the B.1.1.7 variant of concern (VOC), including viral characteristics and clinical severity.
The study, published in The Lancet, demonstrates that there is no evidence of a link between severe illness and death and lineage when comparing the B.1.1.7 lineage and other variants.
The B.1.1.7 lineage
Lineage B.1.1.7, also called 20I/501Y.V1, variant of concern 20DEC-01, or the British variant, was first reported in December 2020 in the United Kingdom.
The B.1.1.7 lineage carries a mutation in the S protein (N501Y) that affects the receptor-binding domain (RBD). The variant has 13 other lineage-defining mutations, many of which are found in the S protein. These include a deletion at positions 69 and 70, which evolved spontaneously in other SARS-CoV-2 variants.
The effect of the structural changes to the spike protein’s properties has sparked concern about transmissibility, pathogenicity, and the variant’s effect on vaccine efficacy. In London, physical distancing restrictions were re-imposed on December 21, 2020, to mitigate the spread of this new variant.
Genomic characteristics and clinical outcomes
To better understand how the B.1.1.7 variant spreads and its effects on the human population, the researchers investigated the genomic characteristics and clinical outcomes tied to the B.1.1.7 infection in patients admitted to the hospital.
They also assessed whether there was a difference in viral load, by proxy of PCR cycle threshold (Ct) values and whole-genome sequencing read depths, between patients with the B.1.1.7 infection and those infected with previous circulating lineages.
To arrive at the study findings, the researchers collected samples positive for SARS-CoV-2 on polymerase chain reaction (PCR) from November 9, 2020, from patients who were admitted to one of two hospitals on or before December 20, 2020, in London, the U.K. These samples were sequenced for the presence of the mutations.
The team investigated the link between the B.1.1.7 lineage and severe illness or death within 28 days of a positive test. Further genomic analyses were performed in a group of chronically shedding patients and a group of remdesivir-treated patients. The team then compared viral load by proxy, using PCR cycle threshold values, and by using sequencing read depths.
The study findings revealed that of the 341 patients with positive samples for SARS-CoV-2. Of these, 58 percent had a B.1.1.7 infection while 42 percent had a non-B.1.1.7 infection.
The team found no link between severe illness and death and the lineages when comparing the B.1.1.7 lineage and other circulating lineages. Further, they detected no B.1.1.7 VOC-defining mutations in 123 chronically shedding immunocompromised patients or 32 remdesivir-treated patients.
Meanwhile, they found higher viral load by proxy in B.1.1.7 samples than in non-B.1.1.7 samples. In terms of age, B.1.1.7 infection is more common in younger people, which gives a hint of more severe disease in patients with the variant are admitted to the hospital more often, compared with patients with other lineages.
The study investigators urged the rapid collection of food quality clinical data, alongside whole-genome sequencing of SARS-CoV-2. These are imperative in deciding whether variants are associated with altered clinical outcomes.
The data and the investigation of neutralization capacity of sera from people who had COVID-19 or those who received a vaccine are essential in the public health response and management of COVID-19.
“Our data, within the context and limitations of a real-world study, provide initial reassurance that severity in hospitalized patients with B.1.1.7 is not markedly different from severity in those without, and this study provides a model to answer the same question again as we move into an era of emerging variants,” the researchers concluded in the study.
To date, the United Kingdom has recorded over 4.39 million infections and over 127,000 deaths. Globally, more than 137 million people have been infected with SARS-CoV-2, while over 2.95 million have died.
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