New, searchable ZIP code-level data gives an up-close look at how contagious variants are keeping New York's case levels at alarmingly high levels.

As variants continue to spread, the original form of the virus is becoming increasingly unusual across the city. Photo credit: Spencer Platt/Getty Images

Despite tens of thousands of people getting vaccinated every day, New York City's coronavirus case numbers have remained alarmingly high for weeks.

Public health officials say one possible reason is that a more contagious variant has replaced the original form of the virus, which accounts for more than 75% of new cases, according to a recent analysis.

The health department releases results from a sample of up to 1,500 sequenced cases each week, providing a citywide snapshot of which variants are increasing.

Until this week, the city had not revealed which variants were more common in which neighborhoods. But newly available postcode-level data provides some insight into the mix of variants prevalent in the region.

Interactive map: Spread of variants in New York City

During February and March, two Covid-19 variants — B.1.526 (first identified in New York City) and B.1.1.7 (first identified in the United Kingdom) — emerged as the dominant form of the virus in New York City. Since then, two other variants have established themselves in the city: P.1 (first identified in Brazil) and B.1.351 (first identified in South Africa).

NOTE: Dots are randomly placed within each zip code and do not correspond to exact addresses. The percentage shows the proportion of total cases sequenced by the epidemic response laboratory. Source: New York City Epidemic Response Laboratory

The messages are a vivid reminder that New York's epidemic dynamics have changed over the past few months, with the original form of the virus becoming increasingly unusual across the city.

"It makes something that is very abstract and maybe difficult to understand become more concrete for people," Dr. Dennis Nash, an epidemiologist at the CUNY Graduate School of Public Health and Health Policy, said of the data. The situation is changing rapidly."

Variants are spreading

The variant first identified in New York, B.1.526, has so far spread more widely in the city than any other variant. There has also been a significant increase in cases linked to the B.1.1.7 variant, which was first identified in the United Kingdom last year and now accounts for nearly 30% of new sequenced cases in New York City.

The B.1.1.7 variant is causing a new surge of disease from Poland to Michigan. It is estimated to be 60% more contagious and two-thirds more deadly than the original virus. This variant is now a leading source of new infections in the United States and Europe.

But that's not the case in New York City, where B.1.526 remains the most prevalent variant, accounting for about 45% of cases sequenced since the fourth week of March.