New York’s top health official tested positive for COVID-19 on Monday as the omicron and delta variants continue their rapid spread.

Dr. Mary Bassett, the acting state health commissioner, immediately left the governor’s Manhattan office after receiving a positive result on a rapid test, Gov. Kathy Hochul said during a COVID-19 briefing at the same site. She said the tests are routinely administered to those who interact on a regular basis with the governor.

She said Bassett is feeling fine and is awaiting the results of a PCR test to confirm her positive status. Bassett became one of a slew of vaccinated elected or appointed officials to test positive on Monday. Maryland Gov. Larry Hogan as well as Senators Cory Booker (D-N.J.) and Elizabeth Warren (D-Mass.) made similar announcements.

All had been vaccinated and boosted, and they reported their symptoms as being mild. Preliminary evidence suggests the omicron variant is more likely to cause these breakthrough infections, but outcomes among people with immunity appear less severe, so far. The potential risks are far worse for unvaccinated New Yorkers, who are being diagnosed with five times more cases and 11 times more hospitalizations than those who have had their shots, according to state’s latest data.

“Of course, [Bassett] is vaccinated and boosted, so this would be a breakthrough case,” Hochul said. “But she’s feeling fine. We’re thinking of her and her family and all the New Yorkers who are having their family plans disrupted by this virus.”

Bassett’s diagnosis comes as New York has seen more than 20,000 people test positive for COVID in each of the last four days.

A total of 23,391 people tested positive across the state on Sunday, setting a new record that doesn’t account for the early days of the pandemic when testing was scarce. Statewide, 4,020 people remained hospitalized for COVID-related reasons, including 1,150 in New York City, according to Hochul.

Much of the rapid spread has been attributed to the omicron variant, which has proven to be easily transmissible. Dr. Mitchell Katz, CEO of New York City Health + Hospitals, said Monday that recently hospitalized people who gained this protection through vaccination or after recovering from a past infection are not getting as sick with omicron. He added that recently hospitalized patients are staying for shorter periods of time and needing less intense treatments relative to previous COVID waves.

“Part of that is that our own treatments are better,” Katz said at a press conference Monday with New York City Mayor Bill de Blasio. “Part of it is that more of the people who get hospitalized now have been vaccinated, and so they have immunity. Or they have prior exposure to the virus.”

Hochul used her Monday briefing to reassure parents that she intends to keep schools open, noting that children over the age of five now have access to a COVID vaccine. The social costs of closing schools, she said, are too high.

“We are keeping our schools open,” Hochul said. “Let me repeat that: We are keeping schools open.”

Instead, Hochul said the state will roll out resources for a “test to stay” program beginning in January for unvaccinated children who may have been exposed to COVID. New Jersey health commissioner Judy Persichilli said Monday that her state would be launching a similar pilot program.

Rather than forcing a full classroom to stay home after a positive test, the state will provide school districts with at-home testing kits to give to the kids in the class — if they test negative, they can return to school, Hochul said.

“We’re working on that supply chain right now,” she said. “Starting in January, we’ll be able to address that.”