COVID-19: Data

New Variants/Strains

The data on this page show how variants of the virus that causes COVID-19 are spreading in NYC. Variants are versions of the virus with certain sets of mutations. Some variants may result in a COVID-19 infection that is easier to spread, more severe or able to avoid antibodies from vaccines or previous infections.

There are not enough data to draw firm conclusions yet about some of the properties of these variants. The Health Department will continue to investigate whether they are more likely to cause reinfections, increase disease severity or reduce the immunity from vaccine or previous infection.

Types of Variants

The CDC classifies some variants as:

  • Variants Being Monitored: There is evidence these were more likely to spread, cause reinfection or cause severe illness, but they are no longer circulating enough to pose a significant risk in the U.S.

  • Variants of Interest: These have genetic markers that have been associated with higher risks of transmission, reinfection or severe illness, as well as reduced vaccine effectiveness.

  • Variants of Concern: There is evidence these are more likely to spread, cause reinfection or cause severe illness, as well as reduce vaccine effectiveness.

  • Variants of High Consequence: There is clear evidence that existing prevention tactics, including vaccination, are less effective against these variants.

Read more about the CDC's classification of different variants.

The table below shows variants that have been observed in New York City and their classification. Currently, B.1.617.2 (delta) is the most widespread variant in the city. We will continue to closely monitor these variants and any new ones as they develop.

Note: To help with reference, the World Health Organization (WHO) has assigned Greek letters to variants, such as: alpha (B.1.1.7), iota (B.1.526), gamma (P.1) and delta (B.1.617.2).

Variant Testing

These charts show the percent of NYC's confirmed COVID-19 cases that have been tested for virus variants and reported to the Health Department, and the total number tested each week.

Spread of Variants in NYC

These charts show the percent and number of tested cases each week that have the four most common variants in New York City: B.1.1.7, B.1.526, P.1 and B.1.617.2.

About the Data

New York City’s Public Health Laboratory, Pandemic Response Laboratory, and hospital and private laboratories have been testing COVID-19 cases to identify emerging variants of the virus.

Cases are tested for variants only if they meet certain criteria, such as having enough virus in the sample. However, these findings are still reliable, as the tested cases generally reflect all cases in NYC.

Download these data on GitHub.