A new COVID variant is climbing the ranks in the U.S., becoming the third-most common strain of the summer.
Variant XFG, colloquially known as “Stratus,” was first detected in Southeast Asia in January but accounted for less than about 0% of cases in the United States until May. By late June, it was estimated to account for up to 14%, according to the Centers for Disease Control and Prevention (CDC).
The World Health Organization (WHO) added XFG to its watchlist but evaluated the additional public health risk posed by the variant as “low” at the global level in a late June report, in which it also advised that currently approved COVID-19 vaccines are “expected to remain effective to this variant against symptomatic and severe disease.”
Here’s what we know about XFG.
What is COVID variant XFG?
XFG is a combination of COVID-19 variants F.7 and LP.8.1.2, the latter of which is currently the second most prominent strain in the U.S.
The variant’s mutations may enhance XFG’s ability to evade immune responses, but its binding behavior shows that it is less likely to be highly contagious than other dominant variants, Subhash Verma, microbiology and immunology professor at the University of Nevada, Reno, told USA TODAY.
“There is currently no clear evidence that XFG causes more severe disease or significantly different symptoms than earlier Omicron variants,” said Verma. “Importantly, there are no immediate public health concerns associated with this variant.”
How common is XFG?
While XFG has been growing and spreading worldwide, it has yet to become the predominant source of infection in the United States.
The CDC has moved to using longer timeframes for COVID tracking due to low reporting from states. According to the latest data for the two-week period ending June 21, XFG accounted for 14% of U.S. cases, making it the third most-prevalent strain after NB.1.8.1 (43%) and LP.8.1 (31%).
The prominence of XFG in the United States significantly increased in the weeks leading up to the last report, accounting for 0% of cases through March before reaching 2% in April, 6% in late May, 11% in early June and 14% in late June.
WHO tracked an uptick in XFG worldwide in June as well, with the June report including data from 38 countries showing that XFG accounted for only 7.4% of positive tests in the first week of May but 22.7% by the last.
USA TODAY has reached out to the CDC for more information about the spread of COVID variants in July and August.
What are the symptoms of XFG?
There is no evidence that XFG causes any distinct symptoms from other variants, said Verma. However, hoarseness has been anecdotally associated with the strain, according to social media posts and news reports.
The CDC outlines the following as common COVID-19 symptoms:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Sore throat
- Congestion or a runny nose
- New loss of taste or smell
- Fatigue
- Muscle or body aches
- Headache
- Nausea or vomiting
The CDC advises seeking medical care if you experience any of the following symptoms:
- Trouble breathing
- Persistent pain or pressure in the chest
- New confusion
- Inability to wake or stay awake
- Depending on skin tone, lips, nail beds and skin may appear pale, gray, or blue
This article originally appeared on USA TODAY

News
New COVID variant ‘Stratus’ is spreading in the U.S. and worldwide
A new COVID variant is climbing the ranks in the U.S., becoming the third-most common strain of the summer. Variant XFG, colloquially known as "Stratus," was first detected in Southeast Asia in January but [...]
Fat Molecule May Control How You Feel Emotion
Key Questions Answered Q: What did researchers discover about the serotonin 5-HT1A receptor? A: They mapped how it activates different brain signaling pathways, offering insight into how mood and emotion are regulated at the [...]
Nanodevice uses sound to sculpt light, paving the way for better displays and imaging
Light can behave in very unexpected ways when you squeeze it into small spaces. In a paper in the journal Science, Mark Brongersma, a professor of materials science [...]
ChatGPT helps speed up patient screening for clinical trials
A new study in the academic journal Machine Learning: Health discovers that ChatGPT can accelerate patient screening for clinical trials, showing promise in reducing delays and improving trial success rates. Researchers at UT Southwestern Medical Centre used [...]
New Study Reveals This Popular Fruit Is Actually a “Superfood”
A new peer-reviewed article argues that grapes deserve a place among today’s top superfoods. A recent article published in the peer-reviewed Journal of Agriculture and Food Chemistry takes a closer look at the term [...]
Experimental Drug Reverses PTSD Symptoms in Mice – Already in Human Trials
Excessive levels of GABA released by astrocytes impair the brain’s ability to extinguish fear responses in PTSD, but a newly identified drug target offers promising hope for treatment. Many people with post-traumatic stress disorder (PTSD) [...]
New high-selectivity nanozyme enables rapid and visible disease diagnostics
To enable early diagnosis of acute illnesses and effective management of chronic conditions, point-of-care testing (POCT) technology—diagnostics conducted near the patient—is drawing global attention. The key to POCT lies in enzymes that recognize and [...]
Globally, over 2.5 million COVID deaths prevented worldwide thanks to vaccines
Thanks to vaccinations against SARS-CoV-2 in the period 2020–2024, 2.533 million deaths were prevented at the global level; one death was avoided for every 5,400 doses of vaccine administered. Some 82% of the lives [...]
RNA-seq outperforms DNA methods in detecting actionable cancer mutations
Hospital for Sick Children in Toronto researchers are reporting that targeted RNA sequencing can detect clinically actionable alterations in 87% of tumors and provide decisive findings where DNA-seq either fails, returns no variant, or [...]
Physicists discover new state of quantum matter
Researchers at the University of California, Irvine have discovered a new state of quantum matter. The state exists within a material that the team reports could lead to a new era of self-charging computers [...]
Researchers create safer nonstick surface, cutting use of ‘forever chemicals’
A new material developed by researchers from University of Toronto Engineering could offer a safer alternative to the nonstick chemicals commonly used in cookware and other applications. The new substance repels both water and [...]
New research identifies critical gene for treatment
Amyotrophic lateral sclerosis (ALS) - which you may know as the disease that affected Stephen Hawking - is a fatal neurodegenerative disease that causes progressive muscle weakness. A research team at Tohoku University and [...]
DNA Nanoflower Targets Breast Cancer Cells in Drug Delivery Breakthrough
Scientists have developed a DNA nanoflower that delivers chemotherapy and gene therapy directly to breast cancer cells, boosting effectiveness while reducing side effects in early tests. Breast cancer continues to be one of the most [...]
New method genetically blocks mosquitoes from transmitting malaria
Mosquitoes kill more people each year than any other animal. In 2023, the blood-sucking insects infected a reported 263 million people with malaria, leading to nearly 600,000 deaths, 80% of which were children. Recent [...]
How Covid led to an ‘acceleration’ in brain ageing (even if you didn’t have the virus)
The Covid pandemic 'significantly' accelerated brain ageing – even among those who were never infected, a study suggests. Scientists say the strain on people's lives, from isolation for weeks on end to the uncertainty surrounding [...]
Novel Sonication Method Creates Realistic Nanoplastics for Pollution Research
Scientists have developed a simple sonication method to create nanoplastics that closely mimic environmental particles, promising more realistic studies of their ecological impact. Plastics like polyethylene, PET, and polystyrene are used worldwide. Through wear [...]