What is ‘Stratus’? Inside the cough that New Yorkers can’t seem to shake

From subway cars to office cubicles, New Yorkers are hoarse and hacking this fall — sidelined by stubborn symptoms that just won’t quit.

While official data indicates that overall respiratory illness activity remains low across the city, experts say the effects of a late-summer surge caused by one particular virus are still being felt.

“[It] may explain the ongoing upper respiratory symptoms,” Dr. Andrew Handel, a pediatric infectious diseases specialist at Stony Brook Children’s Hospital, told The Post.

Enter Stratus: a fast-spreading COVID-19 strain known for causing a persistent, dry cough.

Officially dubbed XFG, Stratus surged past its predecessor “Nimbus” (NB.1.8.1) in September to become the dominant variant in the US, fueling a wave of infections nationwide.

“COVID-19 wastewater viral activity levels are currently high, indicating ongoing community transmission,” Dr. Syra Madad, chief biopreparedness officer for NYC’s public hospitals, told The Post. 

There is a glimmer of good news.

“COVID-19 hospitalizations, while still elevated, have been declining since a peak in late September, and test positivity rates are also decreasing statewide,” said Madad, who also serves as an infectious disease epidemiologist at Harvard’s Belfer Center.

Still, studies show that even mild Covid cases can cause lingering symptoms that outlast the average flu or cold — meaning many New Yorkers infected during the Stratus surge may still be struggling weeks later.

There’s no evidence Stratus causes more severe illness than previous variants, especially if you’re vaccinated. But its stealthy mutations help it dodge immunity from past infections and vaccines, making it more transmissible.

Among its calling cards: a gravelly, hoarse voice, a “razor blade” sore throat and a relentless cough that many mistake for seasonal allergies.

Though, as Handel noted, “pollen levels are not particularly high, making allergies a less likely cause of those same symptoms this time of year.”

And Covid isn’t the only bug on the block.

“October often marks the start of ‘respiratory season,’ ” Handel said, when viruses like influenza, respiratory syncytial virus (RSV) and others begin to circulate.

“At Stony Brook University Hospital, we’re seeing many patients with rhinovirus/enterovirus,” he said, noting that these similar respiratory viruses cannot be distinguished by routine testing. 

“Rhinovirus is the most common cause of cold symptoms and may well explain recent runny noses, congestion and coughing,” Handel said.

How long can this cough chaos last?

Studies show that most viral coughs in healthy adults clear up within 10 to 14 days — but for 1 in 4 people, the hacking hangs on for weeks or even months, according to UCLA Health.

There are two main culprits: postnasal drip, when mucus drains down the throat and triggers irritation, and viral inflammation that leaves airways raw and hypersensitive.

“Hacking coughs that last for weeks are frustrating for patients, impacting sleep and general wellness,” Dr. Benjamin Abella, chair of emergency medicine at Mount Sinai Health System in New York, told The Post.

Over-the-counter cough medicines can help, along with running a humidifier at night, he said.

And don’t underestimate the basics.

“There’s no surefire way to stop the symptoms, but rest and exercise go a long way,” added Handel. “Patients who get outside and go for walks tend to improve more quickly than those who are sedentary.”

Consuming honey or mixing it into a warm drink has also been shown to help relieve cough frequency and severity, particularly for children, he noted.

To further speed recovery, make sure to drink lots of water to prevent dehydration and help loosen up mucus.

OTC saline nasal sprays can clear blocked nasal passages and reduce inflammation, as can nasal rinses like neti pots.

“If a persistent cough is also associated with fevers or an increase in phlegm — coughing up green or yellow mucus — it may be time to see a physician,” ​​Abella said. 

“Sometimes, such a cough can represent a secondary bacterial infection requiring antibiotics,” he explained.