NEW YORK — It just won’t leave us alone.

As New York enters its third pandemic summer, the city has been caught in another COVID-19 wave, with an explosively contagious omicron strain pushing test positivity rates to steep heights.

On Wednesday, the weeklong positivity rate across the five boroughs had reached 14% and eclipsed 20% in parts of Staten Island, southern Brooklyn, Queens, upper Manhattan and the eastern Bronx, according to city data.

Death rates remain low, limited by widespread vaccination, but the latest heinous, hyper-mutated subvariant to vex the globe, BA.5, appears to have sent hospital admissions rates upward in other countries.

“It’s abundantly clear that this is another threat to all of us,” said Dr. Jay Varma, who served as a health adviser to former Mayor Bill de Blasio.

“The risk is lower in those who are fully up to date on their vaccines, but because the virus keeps finding ways to evade our immune systems, it represents a risk of more people getting infected,” Varma said. “We’re just on this roller coaster.”

New York State reported 15 COVID-19 deaths Tuesday; deaths lag behind hospital admissions and cases.

The BA.5 subvariant accounted for about 33% of cases in the city in mid-June, according to government data, a figure that was rising rapidly. The strain is now thought to be dominant in the U.S.

The subvariant has significant mutations from the original omicron strain, according to research, suggesting a winter infection might not ward off a summer coronavirus spell.

“A highly transmissible covid variant is on the rise in NYC, but testing is falling,” Mark Levine, Manhattan’s borough president, said Tuesday on Twitter, urging New Yorkers to use swabs.

The lack of testing — and ubiquity of at-home diagnostics — can distort official case rates, which have been incomplete throughout the 27-month-old pandemic.

Case counts and positivity rates in the city remain much lower than in January, according to state data, but are on the upswing. The city’s seven-day test positivity rate dropped under 1% at one point in March, after the initial omicron surge.

Authorities have mostly responded to recent rises by urging the use of booster shots and frequent testing.

The city scrapped its color-coded COVID-19 alert system last week, a tacit acknowledgment that New York has entered a different pandemic phase after Mayor Eric Adams declined to observe the system’s recommendations when the alert level rose in May.

Still, the mayor said Tuesday that he remains “focused very much on COVID.”

“These new variants are coming,” Adams said at a news conference. “We’re watching closely, looking at the numbers, looking at the indicators to make sure we can pivot and shift.”

He urged New Yorkers to wear masks in high-risk settings, get tested and, when infected, use antiviral treatments, which are now available at city testing sites.

In a statement on Tuesday, Gov. Kathy Hochul underscored the value of vaccines and booster doses, adding, “Parents and guardians, now is a great time to consult with your child’s pediatrician about getting them vaccinated.“

In New York City, 89% of adults have completed an initial vaccine series, according to government figures, but just 47% have received a booster shot.

The Centers for Disease Control and Prevention recommends all Americans age 5 and over get boosted when eligible, and all adults 50 and older get a second bonus jab.

“We do know that the more doses of vaccine you’ve gotten,” Varma said, “the better protected you are.”