Emerging Variants

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Emerging SARS-CoV-2 Variants

Overview

Viruses mutate over time, and as a result, new variants of viruses tend to emerge. Most mutations do not produce clinically relevant changes but occasionally mutations occur that may be beneficial for the virus.

Multiple variants of SARS-CoV-2, the virus that causes COVID-19, have emerged or spread throughout different parts of the world, including the United States. Variant viruses may carry mutations that could be associated with differences in diagnostic test performance, changes in disease epidemiology, clinical outcomes, and effectiveness of certain therapeutics or vaccines.

Download Table PDF 

Emerging SARS-CoV-2 Variants of Concern 

Selected CDC/World Health Organization Designees with Published Clinical Data 
Version 7/30/21

Variant (WHO label/ Pango lineage/origin) Treatment efficacy (in vitro)** mRNA vaccine clinical effectiveness Viral vector vaccine clinical effectiveness Nanoparticle/subunit vaccine clinical effectiveness
Alpha
B.1.1.7

U.K.
2020

Bamlanivimab + etesevimab: Retains neutralization efficacy (FDA EUA)

REGEN-COV (casirivimab + imdevimab): Retains neutralization efficacy (FDA EUA)

Sotrovimab: Retains neutralization efficacy (FDA EUA)

Convalescent sera: Retains neutralization efficacy (Planas, March 2021)

Pfizer-BioNTech vaccine: Preserved effectiveness against infection and severe COVID-19 in the U.K. (Hall, May 2021), Israel (Haas, May 2021), Qatar (Abu-Raddad, May 2021) and Canada (Nasreen, July 2021 -preprint)

Moderna vaccine: Preserved effectiveness against infection and severe COVID-19 in Canada (Nasreen, July 2021 - preprint)
Oxford-AstraZeneca vaccine: Slightly reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in the U.K. (Emary, April 2021) and Canada (Nasreen, July 2021 - preprint) Novavax vaccine: Preserved effectiveness against infection and severe COVID-19 in the U.K. (Heath, June 2021)

Beta
B.1.351

South Africa
2020

Bamlanivimab + etesevimab: Markedly reduced efficacy (FDA EUA; Chen, June 2021)

REGEN-COV (casirivimab + imdevimab): Retains neutralization efficacy (FDA EUA; Wang, March 2021)
Markedly reduced neutralization with casirivimab alone

Sotrovimab: Retains neutralization efficacy (FDA EUA)

Convalescent sera: Moderately reduced neutralization (Planas, March 2021)
Pfizer-BioNTech vaccine: Slightly reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in Qatar (Abu-Raddad, May 2021)

Moderna vaccine: Slightly reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in Canada (Nasreen, July 2021 - preprint)
Oxford-AstraZeneca vaccine: No effectiveness against infection in South Africa (Madhi, May 2021)Reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in Canada (Nasreen, July 2021 - preprint)

Johnson & Johnson vaccine: Reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in South Africa (Sadoff, May 2021)
Novavax vaccine: Reduced effectiveness against infection (Shinde, May 2021)

Gamma
P.1

Brazil 
2020

Bamlanivimab + etesevimab: Markedly reduced neutralization (FDA EUA)

REGEN-COV (casirivimab + imdevimab): Retains neutralization efficacy (FDA EUA)

Sotrovimab: Retains neutralization efficacy (FDA EUA)

Convalescent sera: Moderately reduced neutralization (Wang, June 2021)
No data

(Presumed to be similar to Beta variant based on relevant mutations)
No data

(Presumed to be similar to Beta variant based on relevant mutations)
No data

(Presumed to be similar to Beta variant based on relevant mutations)

Delta
B.1.617.2

India
2020

Bamlanivimab + etesevimab: Retains neutralization efficacy (FDA EUA
Bamlanivimab alone inefficacious 

REGEN-COV (casirivimab + imdevimab): Retains neutralization efficacy (FDA EUA; Planas, July 2021)

Sotrovimab: Retains neutralization efficacy (FDA EUA)

Convalescent sera: Potential moderately reduced neutralization (Planas, March 2021)
Pfizer-BioNTech vaccine: Slightly reduced effectiveness against infection but preserved effectiveness*** against severe COVID-19 after 2 doses in the U.K. (Bernal, May 2021 - preprint; Stowe May 2021 - preprint), Scotland (Sheikh, June 2021) and Canada (Nasreen, July 2021 -preprint)

Moderna vaccine: Slightly reduced effectiveness against infection but preserved effectiveness against severe COVID-19 in Canada (Nasreen, July 2021 - preprint)
Oxford-AstraZeneca vaccine: Slightly reduced effectiveness against infection but preserved effectiveness*** against severe COVID-19 after 2 doses in the U.K. (Bernal, July 2021), (Stowe, May 2021 - preprint), Scotland (Sheikh, June 2021) and Canada (Nasreen, July 2021 -preprint) No data

*As compared with vaccine efficacy/effectiveness against wildtype or D614G variant SARS-CoV-2.

**The susceptibility results refer, as a default, to in vitro testing of sotrovimab against both pseudotyped virus-like particles and authentic SARS-CoV-2 virus. Where results are discordant, both pseudotyped and authentic virus susceptibility is presented. Where only one type of virus was tested, it was in all cases pseudotyped virus. In the case of the Delta variant, binding of the monoclonal antibodies to variant strain was tested with the S-Fuse binding assay. The extent of correlation of neutralizing activity in in vitro cell culture experiments with clinical outcomes is as yet unknown.

*** As compared with vaccine efficacy/effectiveness against Alpha/B.1.1.7 variant.

For further timely information on emerging variants and vaccine efficacy, refer to our COVID-19 Vaccines FAQ.

 

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