As COVID-19 infections continue to escalate in the new year, some patients have been reporting a strange new symptom: night sweats.

Commonly associated with other conditions like the flu, anxiety, or even cancer, night sweats were less commonly associated with COVID before the Omicron variant began to rapidly spread worldwide. They are repeated episodes of extreme perspiration that can soak your clothes and sheets, according to the Mayo Clinic.

Night sweats are one of a few distinct symptoms that appear to separate Omicron from other COVID variants, along with a sore throat. And unlike Delta and the original COVID strain that first hit the U.S., Omicron does not seem to be associated with a loss of smell and taste. Dr John Torres, NBC News senior medical correspondent, said on the Today show that the night sweats are a “very strange symptom.” Dr. Amir Khan of the United Kingdom’s National Health Service also said to look out for night sweats as a sign to get tested for COVID-19.

In the past few weeks, many people have vented their frustration about COVID-induced night sweats on social media. Some Twitter users say that the new symptom just adds more confusion and anxiety about whether a person has COVID or not.

I love how now the new Omicron symptom is night sweats. What can cause night sweats, let's count the ways:

The Flu

Menopause

Anxiety

Panic Disorder

A fever from any number of diseases

A heart attack

The fear born continues!

— Eve (@bohun63) January 1, 2022

Others are trying to spread awareness about the new symptom that is becoming increasingly common.

Although it is now the dominant variant in the U.S., there are still many unknowns about Omicron. Even less is known about its long-term effects. Early research on the Omicron variant from South Africa suggests that the variant may lead to less severe disease. However, the World Health Organization said last week that it is still too early to tell whether the Omicron variant will cause less serious illness because there is not enough data to see how the virus affects the people who are most at risk.

The Omicron variant has now spread worldwide and has helped spur the world to 1.5 million new cases per day, which is double the amount recorded last week. The U.S. also doubled its daily COVID case rate to more than 400,000 cases as of Monday, according to the New York Times.