Fear of a “mystery virus” is spreading through social media platforms such as TikTok, with young people saying they’re not testing positive for COVID-19, flu or RSV, but sharing symptoms of nausea, faintness and excess mucus.

Public health experts say these concerns are likely a sign of one post-pandemic condition: anxiety about getting sick.

“The symptoms that are being described are pretty consistent with, you know, a lot of viruses that are not ‘mystery viruses,’ that are things that are out there circulating all year. The common cold being one of them,” Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, told The Hill.

In the past few weeks, social media users have posted online about their experiences with COVID-like symptoms including difficulty breathing, extreme fatigue and fever. Many videos show people expressing their confusion as they say tests for viruses including COVID-19, the flu and RSV come back negative.

One user on TikTok shared her experience with the “mystery virus” last week, describing symptoms of lightheadedness, nausea and feeling as though she was going to faint. Another social media user described symptoms of congestion, shortness of breath, nausea and having a stye — but testing negative for COVID-19.

“Who else is sick, and what is this ‘unknown virus’ going around?” one user asks. The post had garnered nearly 8,000 comments as of Tuesday, mostly people sharing symptoms and speculating on the cause.

Public health officials who spoke with The Hill said there are currently no indications of a new, unknown virus tearing through the U.S.

According to Georges Benjamin, executive director of the American Public Health Association, a rise in other respiratory infections concurrent with COVID-19 and the flu is to be expected with the season. He noted that the 2023-24 cold and flu season followed several years of isolation due to the pandemic. More in-person socializing could be facilitating more widespread infections than in recent years.

Not only are we seeing each other in person more, people are hearing about others experiencing illness far more than they ever did in the past thanks to online platforms, Benjamin noted.

“This generation tends to tell you everything that’s going on in their lives on social media. In my view, they’re sharing way too much, but that’s them,” he said. “They like to hypothesize about what’s going on. And to some degree, it is self-generating both hysteria and false information. Because, you know, you’re now hearing about things from four or five different people — many of whom you don’t know.”

According to the most recent federal data, COVID-19 emergency hospital admissions have been declining since the start of January, with roughly 19.000 admissions reported for the week of Feb. 17. Flu cases also appear to have peaked, with the weekly surveillance report from the Centers for Disease Control and Prevention (CDC) noting a nearly 15 percent drop in positive tests.

Like many current issues relating to infectious disease, experts see a connection between online concerns about novel viruses and the pandemic.

“Social media failed to tackle repeated waves of health misinformation during the Covid pandemic, and it’s had a lasting effect in creating distrust of real medical experts while breeding a new generation of online quacks,” Callum Hood, head of research at the Center for Countering Digital Hate, said in a statement.

“In this environment, new health hoaxes can spread quickly and are not being tackled by social media platforms. Platforms need to step up and tackle harmful health misinformation instead of profiting from it.”

Lori Freeman, CEO of the National Association of County and City Health Officials, said these unverified online concerns of a “mystery virus” are another indication that trust in governmental and public health authorities is still lagging.

She encouraged people concerned about potential infectious diseases to stay up to date on what federal agencies such as the CDC and the Food and Drug Administration are reporting.

“I think we’re all a little on edge after the pandemic,” Freeman said. “People should rightfully be concerned when they’re not feeling well for extended periods of time, and they should seek out more information for themselves.”

Health experts noted that the pandemic has dominated concerns about pathogens for so long that some people may have forgotten about the plethora of other infections that can be contracted.

“There’s a collective amnesia of what life was like five years ago,” said Benjamin, a longtime physician. “RSV is getting a higher profile and higher billing in conversation because there is a vaccine for it. And we don’t have a vaccine for the common cold yet. And again, it’s almost 200 different viruses.”

Asked how he would advise someone in his own life who was concerned about a “mystery virus” right now, Benjamin said, “I would advise them that this is cold and flu season, and that this is consistent with what we see in cold and flu season. And that if it doesn’t go away in the next 48-72 hours — well, if it gets worse, let me know and I’ll help them get to a doctor.”