Tracking the COVID-19 Variants

7/30/21 The section on the Delta variant was expanded.

6/09/21 A section on the new naming convention was added. 

4/14/21 The section on B.1.17 was updated to reflect new severity data 

3/22/21 A section on the B.1.526 "New York" variant was added.


Given the nature of viruses and how they mutate over time, variants of the COVID-19 virus were expected. Within the last several months, multiple variants of the COVID-19 virus have been identified. Three variants have been identified to date and are circulating worldwide.1

B.1.1.7 / Alpha

Originating from the United Kingdom, this variant was first recognized in September 2020 and has several mutations, including:

  1. N501Y: A mutation in the receptor-binding domain of the spike protein at position 501, where asparagine is replaced with tyrosine2
  2. 69/70 deletion: Occurs frequently and leads to conformational change in the spike protein2
  3. P681H: Existing near the S1/S2 furin cleavage site, which has high variability amongst coronaviruses2
  4. Q27stop: a mutation in the ORF8 stop codon in which the functional change is unknown2


The variant spreads quickly and is now highly prevalent throughout southeast England and London.1 Despite how rapidly the variant spreads, it does not appear to cause a more severe illness or increased risk of death.1 The B.1.1.7 variant has been circulating the United States and Canada, as well as multiple other countries.1

A briefing paper published on January 22, 2021 detailed data from two preliminary analyses that suggested a potential increase in disease severity in patients who contract the variant. However, they noted that further analysis is needed due to the small sample size.6

A report from Moderna on January 25, 2021 stated that their vaccine remains effective against the B.1.1.7 variant.8

Two studies, both published on April 12, 2021, have demonstrated that the B.1.1.7 variant does not increase the severity of COVID-19 infection compared to other variant strains.11,12 Additionally, the variant was not reported to cause worse symptoms or a greater risk of developing long COVID.11,12 The studies did find that, similar to previously conducted studies, the B.1.1.7 variant is associated with increased rates of transmission.11,12 While it was previously thought that the B.1.1.7 variant may increase the risk of reinfection, that proven false as there was no increase in the reinfection rate and vaccines are thought to remain effective against this variant.12

1.351 / Beta

This variant was first detected in South Africa in October 2020 and is distinct from the B.1.1.7 variant. However, they do share several mutations, including N501Y.1,2 One of the mutations in the spike protein, E484K, may change the ability of polyclonal and monoclonal antibodies to neutralize the virus.3,4

A report from Moderna on January 25, 2021 stated that their vaccine remains effective against the 1.351 variant.8 However, the company reported a 6-fold decrease in the level of highly-potent neutralizing antibodies against the 1.351 variant, leading them to add a second booster to the vaccine regiment, for 3 vaccinations in total. It will also begin preclinical studies of a booster specifically for the 1.251 variant.

A report from Novavax showed that while its vaccine was 89% effective against the B.1.1.7 variant, it was only 49% effective against the 1.351 variant. This report was released on the same day that the first cases of 1.351 were identified in the US, in South Carolina.9

P.1 / Gamma

The P.1 variant was first recorded in 4 travelers from Brazil during routine testing in Japan.1 Like the 1.351 variant, the P.1 variant has the E484K mutation, which may affect its ability to be detected by antibodies.2 The P.1 variant has 17 unique mutations, 3 of which affect the receptor-binding domain of the spike protein.2 To date, there is no record of this variant in the United States.1

All 3 variants demonstrate the ability to spread more rapidly, but do not appear to cause a more severe course of illness.1 While the risk of death or illness severity may not increase with these variants, the virulence will put an additional strain on the already-spread-thin health care system.1 Scientists are working to better understand the variants, including how far the variants have spread, how the disease caused by the new variants differs from the current COVID-19 strain, and how these variants may affect developing treatment and vaccines.1 

The Centers for Disease Control and Prevention will continue to conduct SARS-CoV-2 strain surveillance to support public health response.2 As variants continue to emerge, health care providers need to be aware of the potential consequences of variants, including:

  • Ability to spread more quickly. The D614G mutation spreads more quickly than the wild-type SARS-CoV-2 virus.2
  • Ability to cause milder or more severe illness. To date, there is no evidence showing that any identified variant effects the severity of the disease.2
  • Ability to evade diagnostic test detection. Polymerase chain reaction (PCR) tests utilize targets on the virus to detect its presence. Most PCR tests utilize multiple targets so that, if mutation occurs at one target, the PCR test will still detect the virus at its other targets.2
  • Decreases susceptibility to treatment. Specifically, monoclonal antibodies.2
  • Ability to evade immunity, natural or vaccine-induced. Vaccines and natural infection create a polyclonal response to portions of the spike protein. If a variant has multiple spike protein mutations, it may be able to evade vaccine- or natural-infection-induced immunity.2

One of the most concerning consequences of variants is the ability to evade vaccine immunity. For a study conducted in 20 volunteers who received either the Moderna (n = 14) or Pfizer-BioNTech (n = 6) vaccine, researchers analyzed the ability of vaccine-elicited monoclonal antibodies to neutralize the SARS-CoV-2 virus with different variants.5 The researchers found that variants with the K417N/T, E484K, and N501Y mutations can reduce the neutralization ability of vaccines.5 The researchers recommend that COVID-19 vaccines may need to be updated and immunity should be monitored to track and account for viral evolution.5 

Health care providers and the public should not distrust the current vaccines. Despite the presence of genetic variants, the current COVID-19 vaccines are not outdated. The COVID-19 vaccine may need to be treated like the influenza vaccine, where it may need to be periodically updated or updated yearly to prevent potential loss of efficacy.5


This strain was first identified in November 2020 in California, and is now present in 12 counties. Notably, the strain saw a drastic increase in presence over a very short time, jumping from roughly 3.8% of sequenced samples to 25% in less than a month, according to Virologist Charles Chiu.7

It carries 3 mutations in the spike protein, the area of the virus targeted by current vaccines, which could hinder the effectiveness of the vaccine, leading researchers to prioritize this strain in their studies.

B.1.526 / Iota

The new strain was first identified in New York City in November 2020. As of February 2021, the variant accounted for 27% of sequences in the GISAID database.10

B.1.617.2 / Delta

On June 18, 2021, WHO announced that the Delta variant, first identified in India, was becoming the dominant variant worldwide. They cited the variant's “significantly increased transmissibility,” as the reason for its domination.14

On July 30, 2021, a WHO document stated the the Delta variant was nearly as transmissable as chickenpox, with each infected person infecting 8 to 9 others, compared with the original strain of SARS-CoV-2 which was as transmissable as the common cold (~2 infected by each person). Further, it showed that fully vaccinated individuals infected with the variant, whether or not they show symptoms, can still pass the virus on to others as much as an unvaccinated person can.15

Naming Convention

On May 31, 2021, the World Health Organization announced a new naming system for the COVID-19 variants. Instead of identifying the variants based on where they were first detected, the new naming convention will use the Greek alphabet.13 The initiative is in effort to reduce stigma associated with the first detection of a new variant, as well as increase accuracy as some variants have independently emerged in several places.13 This new naming convention will not replace the scientific names of each variant.13 

Scientific NameFirst IdentifiedWHO Label
B.1.1.7United Kingdom, Sept 2020Alpha
B.1.351South Africa, May 2020Beta
P.1Brazil, Nov 2020Gamma
B.1.617.2India, Oct 2020Delta
B.1.427/B.1.429United States, Mar 2020Epsilon
P.2Brazil, April 2020Zeta
B.1.525Multiple countries, Dec 2020Eta
P.3Philippines, Jan 2021Theta
B.1.526United States, Nov 2020Iota
B.1.617.1India, Oct 2020Kappa


—Audrey Amos, PharmD


  1. New COVID-19 variants. Centers for Disease Control and Prevention. Updated January 15, 2021. Accessed January 22, 2021.
  2. Emerging SARS-CoV-2 variants. Centers for Disease Control and Prevention. Updated January 15, 2021. Accessed January 22, 2021.
  3. Greaney AJ, Loes AN, Crawford KHD, et al. Comprehensive mapping of mutations to the SARS-CoV-2 receptor-binding domain that affect recognition by polyclonal human serum antibodies. BioRxiv. Published online: December 31, 2020. doi:10.1101/2020.12.31.425021
  4. Weisblum Y, Schmidt F, Zhang F, et al. Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants. Elife. 2020;9:e61312. doi:10.7554/eLife.61312
  5. Wang Z, Schmidt F, Weisblum Y, et al. mRNA vaccine-elicited antibodies to SARS-CoV-2 and circulating variants. BioRxiv. Published online: January 19, 2021. doi:10.1101/2021.01.15.426911
  6. Iacobucci G, COVID-19: New UK variant may be linked to increased death rate, early data indicate. BMJ.
  7. Another coronavirus variant found more frequently in California, including in L.A., Orange, Riverside counties. KTLA5. Published January 17, 2021. Accessed January 26, 2021.
  8. Ahmed I. Moderna says COVID vaccine effective against UK, S. Africa variants. News release. Moderna. January 25, 2021. Accessed January 26, 2021.
  9. Johnson CY, Achenbach J. Coronavirus variant first seen in South Africa identified in South Carolina. Washington Post. Published online: January 28, 2021.
  10. Mandavilli A. A New Coronavirus Variant Is Spreading in New York, Researchers Report. Published February 24, 2021. Updated March 17, 2021.
  11. Ong SWX, Young BE, Lye DC. Lack of detail in population-level data impedes analysis of SARS-CoV-2 variants of concern and clinical outcomes. Lancet Infect Dis. Published online April 12, 2021. doi:10.1016/S1473-3099(21)00201-2
  12. Graham MS, Sudre CH, May MA, et al. Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study. Lancet Public Health. Published online April 12, 2021. doi:10.1016/S2468-266(21)-00055-4
  13. WHO announces simple, easy-to-say labels for SARS-CoV-2 variants of interest and concern. News release. World Health Organization; May 31, 2021. Accessed June 9, 2021. 
  14. Lovelace Jr B. WHO says delta is becoming the dominant Covid variant globally. NBC News. Published June 18, 2021.
  15. LeBlanc P, Fox M, Cohen E. CDC document warns Delta variant appears to spread as easily as chickenpox and cause more severe infection. CNN. Published July 30, 2021.