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The fast spread of the Omicron variant has fueled fears about a wave of long COVID cases.
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  • The Omicron variant of the coronavirus seems to be causing similar symptoms as previous variants.
  • Although current evidence suggests Omicron is less likely to cause severe illness, scientists are warning that it should not be treated as mild and the long-term effects are still unknown.
  • Research shows that even mild cases of COVID-19 can trigger long COVID.
  • If you experience lingering symptoms and suspect you may have long COVID, experts recommend seeking a primary care physician or a specialist clinic to confirm.

As the Omicron variant of the coronavirus continues to sweep across the United States, another important question has emerged for scientists worldwide: Will more transmission equal more long COVID cases?

The rate of hospitalization has also been rising for the highly transmissible Omicron variant. But experts concur that more time is needed to know the long-term effects of these COVID-19 infections.

From what we have seen from previous variants, there is no evidence yet to claim that Omicron will not cause long COVID.

Here is what we know so far.

According to the Centers for Disease Control and Prevention (CDC), long COVID, also called chronic or long-haul COVID, is a range of more than 50 symptoms that may last for weeks or months after a person experiences a COVID-19 infection.

There has not been an apparent difference in symptoms between acute COVID-19 infections caused by Omicron versus those caused by other variants such as Delta.

The top symptoms with Omicron infections, according to a ZOE study, are:

  • runny nose
  • headache
  • fatigue
  • sneezing
  • sore throat

“Though there is some indication that the Omicron variant spreads more easily, fortunately, the early data seem to indicate that the variant may cause less severe disease within the population,” said Dr. Scott Lillibridge, physician, epidemiologist, and the director of emergency response for International Medical Corps.

Even though so far the majority of the population is experiencing more cold-like, milder symptoms with Omicron, this could be due to a higher level of immunity (via infection or vaccines) in the population, experts stress.

“[M]any Omicron infections in the U.S. are breakthrough infections [infections in vaccinated persons] as the majority of the population is fully vaccinated. One expects a less severe course in a vaccinated person,” said Dr. Marisa Montecalvo, professor of medicine and medical director for NYMC Health Services at New York Medical College.

A COVID symptom study in the United Kingdom found that vaccinated people were 49 percent less likely to develop long COVID after a COVID-19 infection.

However, Montecalvo noted that some people may still experience moderate-severe disease.

There will always be exceptions for any variant, especially for people with underlying health issues, said Lillibridge.

Tracking long COVID cases has been a challenge, as many health entities and countries have different practices and requirements for symptoms to be classified as such.

The United Kingdom, for example, says that for the symptoms to be considered long COVID, the patients must be experiencing them for at least 3 months. Whereas for the CDC, this time period is 4 weeks or more.

In addition, as Omicron only emerged in November 2021, not enough time has passed for patients or doctors to notice signs of long COVID.

All people who had COVID-19 infections, whether they were hospitalized or only had slight symptoms, can experience long COVID.

Studies have shown that even mild cases of COVID-19 can trigger persistent symptoms.

In a recent interview, U.S. infectious disease expert Dr. Anthony Fauci reiterated that long COVID was a possibility regardless of the variant.

“Long COVID can happen no matter what virus variant occurs. There’s no evidence that there’s any difference between Delta or Beta or now Omicron,” he said.

Previous research has estimated, on average, up to 30 percent of patients go on to develop long COVID.

Studies have also found that 1 in 7 children and young people may still have symptoms linked to COVID-19 15 weeks after initial infection.

Montecalvo underscored that long COVID could certainly be an outcome with Omicron infections but that for the time being, its incidence rate was unknown.

Some experts believe that the incidence of long COVID may be lower as Omicron does not seem to cause a high or persistent rise in inflammatory markers in the body during infection. Long COVID has often been more debilitating in severe cases with serious inflammation.

Andrew Catchpole, DPhil, virologist and chief scientific officer at hVIVO, which carries out human challenge studies for infectious diseases, said he does not expect a higher incidence of long COVID cases in proportion to infections with Omicron.

“While Omicron is more infectious, infectivity is not linked to an increased likelihood of long COVID. It is more linked to severity. [As] on average, Omicron infections are less severe than what was seen with other variants or the original strain, we would expect the proportion of long COVID cases to be lower with Omicron,” he told Healthline.

Catchpole said that diagnosing long COVID was dependent on both the symptom and its duration.

“In terms of the symptoms associated with the acute disease while the patient is infectious, we would expect them all to resolve within 10 to 14 days,” he told Healthline.

Such symptoms could be a runny nose, sore throat, breathlessness, fever, muscle aches, lethargy, and even on some occasions diarrhea and nausea, he said.

“If any of these [symptoms] persist for longer, that would be unusual. [A]nything still apparent 1 month after first symptom onset is worth further investigation by a doctor.”
– Dr. Andrew Catchpole

Lillibridge said persistent shortness of breath, fatigue, and trouble concentrating were the most troublesome symptoms that pointed to a need for deeper investigation.

If you are experiencing these symptoms or more after your infection and they persist beyond 2 to 3 weeks of recovery from your acute illness, follow up with your healthcare provider, he told Healthline.

Catchpole also warned that two symptoms, in particular, may not be a cause for concern when it comes to long COVID.

Catchpole said a loss of taste and/or smell can persist for weeks or months, with over 3 months being relatively common.

“I would suggest one speak with their physician at any point in which they are concerned about a symptom. One would not want to attribute a symptom to ‘long COVID’ that could be a manifestation of another problem,” Montecalvo said.

There also has been concern around reinfections reigniting long COVID symptoms in people who had COVID-19 infections previously.

One such case is a Spanish healthcare worker who contracted the original strain in February 2020, the Delta strain in July 2021, and Omicron in November 2021.

The reinfections have caused her to experience chronic pain, fatigue, and memory loss, among other symptoms.

It is too early to tell whether Omicron will lead to more long COVID cases and experts are divided.

One camp argues that the perceived reduction in disease severity and higher immunization will help protect against long COVID.

Meanwhile, others believe Omicron’s high transmissibility will multiply the number of long COVID cases, causing the condition to become a chronic public health concern.

Although getting vaccinated significantly lowers the risk of developing long COVID, reinfection may cause a flare-up in symptoms.

If you have persistent symptoms such as brain fog, muscle aches, fatigue, or similar after a COVID-19 infection, it may be best to contact your healthcare professional and get advice from a Post-COVID Care Center in the United States.

Patient advocacy groups for people with long COVID, such as Survivor Corps, are also good sources of information and emotional support.