Two coronavirus variants—the ones first identified in New York City and the United Kingdom—have spread across all five boroughs, according to a new report from the city Health Department released Monday. The pair of mutants have taken over the bulk of cases that undergo genomic sequencing analysis, now accounting for nearly three of every four. But officials don’t have evidence yet that the variants are causing reinfections or breaking through vaccine protection.

The report details how the landscape of variants in New York City has rapidly shifted since January, as the city’s surveillance programs ramped up. The New York City variant, called B.1.526, makes up the majority of those sequenced cases. The U.K. variant (B.1.1.7) has also risen sharply, as it has done across the nation to become the dominant form of the virus in the U.S. NYC officials are reporting a small increase of the variant from Brazil (P.1), but it so far makes up few of the cases sequenced.

The proportion of the U.K. and New York City variants among cases sequenced is rising in the five boroughs.

The city’s Public Health Lab as well as the public-private partnership at the Pandemic Response Lab are now sequencing more than 5% COVID-positive nose swabs per week. The duo has found that variant cases are scattered around the five boroughs but are concentrated in some sections. Data in ZIP codes with fewer than three sequenced cases were omitted.

The New York City variant is slightly more common in the Bronx and in Queens.

The New York City variant (B.1.526) is slightly more common in the Bronx and in Queens.

The one from the U.K. is elevated in southern Brooklyn, eastern Queens, and Staten Island—but overall has fewer cases around the city compared to the New York City strain.

The U.K. variant (B.1.1.7) is slightly elevated in southern Brooklyn, eastern Queens, and Staten Island.

Genetically sequenced COVID-19 cases are reported to a global database called GISAID, and variants accounted for 10% of NYC-based submissions in January. They now make up 70% as of mid-March. New variants are setting the stage for what the pandemic will look like this year, and health experts have worried the mutants are in a race against local vaccine campaigns.

The city report said the variants explain the recent high plateau of COVID-19 cases in the city. Since mid-February, daily COVID-19 cases have mostly remained between 3,000 and 4,000, though city data from the first week of April suggests cases are sliding downward, again. That’s the lowest since early December, but for comparison, new positives hovered between 300 and 600 from July to September when the city was safely in a lull. The infection rates across four of the five boroughs—Manhattan, The Bronx, Brooklyn and Queens—are slightly below 1.0, meaning the outbreaks are shrinking at a slow pace there. Staten Island has a larger infection rate and the highest case rate of the five boroughs. The infection rate across the metro area (which includes counties in New Jersey and Pennsylvania) is overall less than one.

Research shows that the U.K. variant is 50% more transmissible and can also make people sicker. Scientists don’t yet fully understand the infectiousness of the NYC variant—but city health officials acknowledge it is likely to be more transmissible.

The report also emphasized “there is no evidence to date” that shows either variant reduces the effectiveness of COVID-19 vaccines. Infectious disease experts still remain concerned about the New York City variant, however, because it can have a specific mutation known to help the virus evade our bodies’ defense systems. That mutation is known as E484K, which scientists refer to as “Eek.”

The city says it is closely searching for any potential cases that would indicate an alarming shift—like hospitalizations or deaths among variant cases or patients who’ve recovered from infections with the original strain and now been reinfected by a variant.

The health department noted, “It is too early to know if either of these variants are more likely to cause reinfection or vaccine breakthrough compared to other previously circulating variants.” It emphasized key precautions New Yorkers should take: mask wearing, distancing, staying home if sick, and washing your hands.