Stratus variant becomes predominant in U.S. as nine states report rising COVID-19 cases

A strain of COVID-19 known as Stratus, or XFG, has become the predominant variant circulating in the United States, according to the Centers for Disease Control and Prevention. Wastewater monitoring across multiple jurisdictions shows Stratus leading the spread for the week of Sept. 15, with case numbers rising in nine states: New York, New Jersey, Delaware, Vermont, Michigan, Wisconsin, Minnesota, North Dakota and South Dakota. The World Health Organization first identified Stratus after it was detected in Southeast Asia in January, and it had spread to 38 countries by June, prompting its designation as a SATS-CoV-2 variant under monitoring.

Health officials say Stratus has mutated in a way that helps it evade parts of the immune system and attack it more effectively than the Nimbus strain, though the change is described as marginal and not a cause for widespread alarm. Stony Brook Medicine, the health system affiliated with Stony Brook University in New York, notes this immune-escape feature could make the strain harder to combat for those who are unvaccinated or have not been previously infected, even as it emphasizes that the overall risk to the general population remains low for most people. The department adds that wastewater data currently designate Stratus as the predominant variant in the United States.

The Stratus variant is associated with a symptom profile that overlaps with other COVID-19 infections. In vaccinated individuals, most infections appear mild, with fatigue, fever and a persistent, dry cough among the most common complaints. Officials caution that a broader range of symptoms may occur, including shortness of breath, chest tightness, sore or scratchy throat, headaches and body aches, upset stomach, nausea or loss of appetite, brain fog or trouble concentrating, and a diminished sense of taste or smell. The loss of smell, once a hallmark of COVID-19, is reported less frequently with newer strains, but consumers should monitor for any combination of these signs and seek medical advice as needed. An at-home rapid test remains a common first step for diagnosis.

Medical experts advise individuals to seek care if a high fever exceeds 103°F lasts more than three days, or if symptoms worsen after an initial improvement. Those at higher risk for severe illness — older adults, people with chronic conditions, and the immunocompromised — are urged to stay up to date with recommended vaccines and boosters as new data about Stratus emerge. In addition to vaccination, public health guidance continues to emphasize layered protections such as masking in crowded or indoor spaces, improving indoor ventilation by opening windows or using air filters, frequent handwashing, and avoiding close contact with others when feasible. Travelers are encouraged to check local COVID-19 numbers and guidance before departing.

Some researchers have reported that a simple nasal spray may significantly cut infection risk, according to a study cited by Fox News. Officials say this is not a substitute for vaccination or other preventive measures, but it could be a potential supplementary option as the virus evolves. The guidance to rely on vaccination, masking where appropriate, and good ventilation remains the primary defense for most people.

Public health authorities continue to monitor Stratus through genomic surveillance and wastewater analysis to assess its spread and how well vaccines protect against it. The evolving picture underscores the importance of staying informed about local transmission levels and maintaining up-to-date vaccination status, especially as winter months approach and respiratory illnesses typically increase.

As researchers and clinicians collect more data on Stratus, health officials stress that proactive steps—getting vaccinated, staying home when sick, testing when symptoms arise, and following local guidance—are essential to reducing the risk of severe illness and limiting spread across communities.