Section 1.1: Evolution of N501Y

Researchers theorize that the N501Y strain likely emerged in a limited number of individuals, rather than evolving gradually through widespread infections. In cases where patients battled Covid-19 for extended periods, the virus might have mutated more rapidly to evade the host’s immune responses.

Genomic sequencing has shown that patients who did not recover quickly exhibited a higher mutation rate, particularly those treated with remdesivir and convalescent plasma. Experts from the U.K. have proposed a sequence of events, which still requires validation:

• The immune response in immunocompromised individuals may be weak or absent.
• Antibody treatments can exert strong selection pressure due to high concentrations of antibodies.
• Chronic infections may lead to a substantial and diverse viral population, creating conditions ripe for rapid genetic changes.

Section 1.2: Emergence of N501Y

Current evidence suggests that the N501Y strain evolved independently within the U.K. around September 2020, as reported by the British Medical Journal (BMJ). This strain is also referred to as VUI-202012/01, the first “Variant Under Investigation” identified in December 2020, and is classified as belonging to the B.1.1.7 lineage.

A parallel strain has been identified in South Africa, which is also spreading rapidly, as noted by virologist Tulio De Oliveira from the University of KwaZulu Natal. This South African variant is designated 501Y.V2.

The WHO has confirmed that the N501Y mutations found in the U.K. and South Africa have developed independently. Preliminary analyses shared by Assoc. Prof. Oliveira highlighted the differences between the two strains.

The South African variant features 15 mutations, including eight in the spike protein, while the U.K. variant has 14 mutations, with six in the spike protein. Initial reports from Spain suggested that this strain might increase Covid-19 mortality by 50%, but further investigation revealed that those findings were flawed.

As of January 1, 2021, the new strain had been detected in 20 countries, with some attributing its presence to imports from the U.K.

Section 1.3: Mutations and Their Significance

The designation N501Y refers to the mutation of the amino acid asparagine (N) at position 501 to tyrosine (Y). However, this strain is characterized by a total of 17 mutations, with N501Y being the most notable due to its location in the spike protein.

For further details on the distinction between strains and variants, see here:

Many SARS-CoV-2 Variants Are Present, but Only One Matters

Scientists have assessed over 100 distinct SARS-CoV-2 variants — how many strains were identified?

Section 2.1: Virulence and Transmissibility

Only a few studies have offered insights into the biological properties of the N501Y strain. Reports indicate that mutations transforming the amino acid at position 501 enhance the virus's ability to bind to the human ACE2 receptor.

One significant study published in the journal Science involved researchers who conducted an innovative experiment using mice to simulate natural evolution of SARS-CoV-2. They found that as the virus passed through generations of infected mice, it became increasingly virulent, exhibiting more severe symptoms and enhanced viral replication.

The identified N501Y mutation was linked to improved binding efficiency to the ACE2 receptor, indicating a potential increase in disease severity. However, it's crucial to note that this mouse-adapted virus may not directly correlate with the current strains circulating in humans.

Nevertheless, anecdotal evidence from South Africa points to a shift in the demographics of hospitalized Covid-19 patients, with more young individuals without underlying health conditions being affected.

As of January 1, 2021, preliminary data from Public Health England indicated no significant differences in mortality rates between those infected with the new strain and those with older variants.

Section 2.2: Prospects and Future Research

Health authorities have raised concerns about potential re-infections with the new SARS-CoV-2 strain. Documented cases of re-infection have occurred, typically involving distinct strains of SARS-CoV-2.

When a re-infection is suspected, sequencing the virus's genome is essential to check for the N501Y mutation or other variants. Monitoring re-infected individuals is crucial to identify any resistance to treatments or vaccines.

Future research must focus on the biological characteristics of newly emerged strains, as our understanding of their virulence, transmissibility, and vaccine susceptibility is still limited. Importantly, changes in the virus’s genome don’t always lead to significant alterations in its biological behavior.

Currently, experts assert that there is no evidence suggesting that the N501Y variant will evade vaccination or the human immune response. However, any instances of vaccine failure or re-infection should be prioritized for genetic sequencing.

The emergence of this variant underscores the importance of controlling viral mutations. Although SARS-CoV-2 has a lower mutation rate than other viruses, it can still evolve significantly over time. Effective strategies, including vaccination, social distancing, and hygiene practices, are essential in minimizing the risk of further mutations.