What are the implications of the global emergence of SARS-CoV-2 variants in terms of disease severity and vaccine and treatment efficacy?
As 2021 opens there are multiple variants of the SARS-CoV-2 virus circulating worldwide. Virus mutation is expected and scientists on every continent have been monitoring changes in the virus since its appearance in China late in 2019.
In the short slide show below, we address the ongoing questions about the transmissibility of the variants, their ability to induce more severe disease, whether they are detectable using current testing methods, and importantly, whether the current FDA-approved vaccines will protect against them. Included are statements from leading public health agencies and the vaccine manufacturers.
The UK Variant * B.1.1.7 lineage.
First reports of variant emerged in the UK during September 2020. Since December 20, 2020, 33 countries have reported cases of the B.1.1.7 lineage, including the US & Canada.
8 mutations affect the spike protein—the most important mutation (N501Y) affects the receptor binding domain of the spike protein; could allow virus to more strongly attach to cells.
The UK Variant * Spread.
72 cases of infection to date in the United States. Variant displays increased transmissibility of 50% to 70%.
There is no current evidence that B.1.1.7 causes more severe disease or that vaccine efficacy will be any less robust.
The South Africa Variant * B.1.351 lineage
First reported in South Africa during October, December 2020. As of this writing, variant ahs been identified in 7 countries, not including the US.
The South Africa Variant * The same & different
Like UK variant, has multiple mutations in spike protein, including N501Y. It does NOT contain the deletion at 69/70 that likely leads to a conformational change in the spike protein.
Early research suggests B.1.351 is associated with greater human viral load. Currently there is no evidence to suggest that this variant has any impact on disease severity or vaccine efficacy.
Potential Consequences of Variants * Rapid spread, severe disease
Ability to spread more quickly in people.
Ability to cause either milder or more severe disease in people.
Potential Consequences * Variants may evade detection, therapy
Ability to evade detection by specific diagnostic tests.
Decreased susceptibility to therapeutic agents such as monoclonal antibodies.
Potential Consequences * variants may evade immunity
Ability to evade natural or vaccine-induced immunity
Moderna Statement on Vaccine Efficacy against SARS-CoV-2 Variants, December 23, 2020
Pfizer Statement on Vaccine Efficacy against SARS-CoV-2 Variants, January 8, 2021
