Summary of variant information for COVID-19 virus

Variant of COVID-19 virus WHO Label Risk for increasing transmission Risk for causing more severe disease or death Risk for causing reinfection Risk for impacting vaccine efficacy
UK Variant (VOC)
Alpha Medium Medium Low Low
South Africa Variant (VOC)
Beta Medium TBD Medium Medium
Brazil Variant (VOC)
Gamma High Medium Medium Low/Medium
B.1.617.2 / AY.1 / AY.2 / AY.3
India Variant (VOC)
Delta High Medium/High Medium Medium
B.1.429 / B.1.427
California Variant (VOC)
Epsilon Low TBD Low/Medium Likely Low
B.1.526 / B.1.525
New York Variant (VOI)
Iota / Eta TBD TBD Low/Medium Low/Medium
Brazil Variant (VOI)
Zeta TBD TBD Low/Medium Low/Medium

Note: The variant risk is estimated based on information from the CDC and literature review. This estimate is preliminary and subject to changes as more data and research results become available.


How has COVID-19 virus (SARS-CoV-2) mutated?

While there are thousands of COVID-19 virus mutations, resulting in many strains of the virus with slightly different genetic makeup (variants), only a handful account for the majority of cases of infections. Certain "significant variants" of coronavirus (VOC/VOI) are replacing the original strain as the dominant forms of the virus. This trend is seen in both New York City, and on the national level.

The graphs below show the estimated proportion of "significant variants" (VOC & VOI) among all common variants circulating in New York City (NYC) versus United States.

Note 1: Estimates for NYC are derived from a subset of specimens submitted to the New York City Pandemic Response Laboratory (PRL) for diagnostic testing and may not be completely representative of all NYC COVID cases. Source: NYC Health

Note 2: Estimates for United States are based on more than 175,000 sequences collected through CDC’s national genomic surveillance since Dec 20, 2020 and grouped in 2-week intervals. Data are subject to change over time and will be updated as more data become available. Source: CDC

Prevalence of significant variants of COVID-19 virus

The Delta variant has overtaken the Alpha (UK, B.1.1.7) variant and the local B.1.526 (Iota, NY) variant as the dominant strain in NYC. The Delta variant is also the most prevalent on a national level.

To understand the characteristics of different variants and potential risk, please see the Summary of Variant Information.

Definitions of VOC and VOI per CDC

  • Variant of Concern (VOC)
    A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g. increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.
  • Variant of Interest (VOI)
    A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity.