Health officials say they are looking into whether the Washington Heights variant causes a higher risk of reinfection by other variants or is more resistant to vaccines, but they know it’s more contagious

More contagious variants are keeping the five boroughs’ daily COVID case counts at a “high plateau” even as the vaccination rollout accelerates, and city officials are looking into whether one that first emerged in Washington Heights last year is more likely to cause reinfection among people who previously had the virus, health officials say.

They’re also still looking into whether it is more likely than other variant types to infect people who have been fully vaccinated and whether that Washington Heights variant, known as B.1.526, contributes to more severe outcomes in terms of deaths, hospitalization and illness, a new health department analysis published Monday says.

The Washington Heights variant, along with the U.K. (B.1.1.7), Brazilian (P.1) and South African (B.1.351) strains have proven to all be more transmissible than earlier strains of COVID, which is why they are known as “variants of concern” or “variants of interest.”

The B.1.1.7 strain is described as a “variant of concern” because evidence shows it causes more severe infections than earlier strains. It may also be more lethal. The P.1 variant also is considered a variant of concern because evidence shows antibodies from previous infection or from vaccination may be less effective against it.

While research is ongoing to assess the potential threat level from B.1.526, health officials say it accounts for about 34 percent of all positive sample studied since January. The prevalence of all variants has increased dramatically since January.

At that point, variants of concern and variants of interest accounted for about 10 percent of all cases studied. By mid-March, they represented more than 70 percent of cases genetically sequenced in labs. The Brazilian variant accounts for only about 2 percent of samples studied since January, but city officials say its presence is growing.