Fears about a 'mystery virus' spread through TikTok - among young people who say they're not testing positive for COVID, flu or other common bugs

Fear is rampant on social media platforms about a ‘mystery virus’ that has caused Covid-like symptoms, despite many having tested negative for the virus, as well as flu and RSV.

People have described being sick for weeks on end with high fevers, nausea, trouble breathing, loss of sense of smell, and fatigue.

But health experts say the virus is less mysterious than it is painted online. There are viruses circulating at all times of year, and this ‘mystery virus’ is likely one of the common seasonal illnesses that were suppressed during the Covid pandemic.

There is thought to be a two-pronged effect at play. People are hypersensitive to their own health after the pandemic, and our immune systems were weakened due to things like lockdowns and working from home, when we were not exposed to germs, making illnesses feel more brutal.

The current test positivity rate is about eight percent. While that rate has been on the decline, immunologists are still concerned about it circulating in the community, citing evidence in wastewater samples

While thousands called their illness a mystery virus, their reported symptoms do not necessarily overlap. Some have likened it to a respiratory infection similar to Covid, while others have described symptoms consistent with strep throat.

Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials, told The Hill: ‘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.’

A rise in other respiratory infections concurrent with Covid and the flu is to be expected with the season, and with more people socializing in person, the spread of an infectious disease becomes much more likely.

And because Covid has been a top health concern for years, it is also likely that people have, in a way, forgotten that there is an exhaustive list of other infections that could strike throughout the year.

Dr Georges Benjamin, a longtime physician and executive director of the American Public Health Association, said: ‘There’s a collective amnesia of what life was like five years ago.

‘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.’

He added: '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.'

One user on TikTok describing her illness said: ‘I was sick a few weeks ago for about two weeks. The first four days were absolutely terrible. I tested for Covid, I tested for both a and b flu, I tested for strep, and was negative for everything twice.

‘I had a fever, pretty much for four straight days, I was super congested, shortness of breath, loss of sense of smell. Everything you would think of whenever you have covid or the flu. I was also really dizzy and lightheaded a lot.’

Another one said: ‘Y’all have the virus that’s going around the United States right now? The one with a sore throat that hurts no matter what you drink, the constant mucus that suffocates you in the middle of the night, the severe ear pain, the migraines, the body aches that feel like you just played a basketball game and no subs were called in for you? Fever, the chills?

‘You know, basically, strep, the flu, a normal cold, and bronchitis all basically mixed together?’

Some experts have posited that, contrary to what many are saying, the fault could be Covid. Many are quick to remind people on social media that the virus is still circulating in the US, albeit at far lower levels than in previous years.

MAP: Sea of red engulfs US as tripledemic hits America 

Across America, 38 states are now reporting 'high' or 'very high' levels of flu-like illness, up 19 percent in a week and nearly three times the level a month ago. 

A new strain, JN.1, entered public health experts’ radar earlier this year, accounting for an estimated 83 percent to 88 percent of all circulating variants toward the end of January

Dr Zachary Rubin, an immunologist with expertise in allergies and asthma, said: ‘It’s probably not much of a mystery because people haven’t been talking about it lately, but Covid-19 is still circulating at high levels throughout the United States.

‘We see high levels in wastewater when people go to the bathroom. You shed that virus and we cansample that to see what’s going on in the general population, even if people aren’t testing for it.’

He added that many people use home diagnostic tests, which can give false negative results. It’s best to test several times over 24 to 48 hours or to get a PCR test in a doctor’s office.

‘So this is still something that is going around, making people not only sick but severely sick and having lingering symptoms.’

At the same time, Covid test positivity rates are the lowest they’ve been in weeks. According to data from the Centers for Disease Control and Prevention, about eight percent of Covid tests have come back positive in the past week, down from 9.7 percent two weeks ago and 10.2 percent three weeks ago.

The explosion in testimonials about the concerning so-called mystery virus is directly connected to pandemic-related anxiety and the spread of dubious health claims, according to Callum Hood, head of research at the Center for Countering Digital Hate.

He said: ‘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.’