The omicron variant of SARS-CoV-2 (PANGO B.1.1.529) spread rapidly around the world, surpassing previous variants shortly after it was first detected in November 2021. According to the Our database World in Data COVID-19, in Europe, the number of confirmed cases reported between December 2021 and March 2022 (omicron period) has exceeded all previously reported cases.
Omicron appears to cause less severe acute illness than previous variants, at least in vaccinated populations. However, the possibility of large numbers of people experiencing long-term symptoms is a major concern, and health and workforce planners urgently need information to appropriately scale resource allocation.
Overall, we found in this study a reduction in the odds of long COVID with the Omicron variant versus the delta variant of 0·24–0·50 depending on age and time since vaccination. However, the absolute number of people experiencing long COVID at any given time depends on the shape and width of the pandemic curve.
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What was described as the first peer-reviewed report to investigate Omicron and patients’ risk of persistent symptoms found that 4.4% of Omicron cases resulted in long COVID .
That’s well below the nearly 11% associated with the Delta variant, which was the dominant strain of SARS-CoV-2 early in the pandemic, the researchers said.
But because the Omicron variant is much more contagious than Delta, more people become infected with Omicron and therefore more experience long-term COVID, they added.
"We still need to continue to support people with long COVID as we try to understand why it happens and how we can treat it," said lead researcher Claire Steves, a senior clinical lecturer at Kings College London.
Long COVID can include a variety of symptoms and last weeks, months, or possibly years, affecting a person’s quality of life, according to the U.S. Centers for Disease Control and Prevention. Sometimes, Symptoms may disappear or come back.
They may include fatigue, fever, malaise, shortness of breath, cough, chest pain, palpitations, and dizziness. People may also have confused thinking, depression, anxiety, headaches and problems sleeping, as well as loss of smell and taste. Diarrhea, stomach pain, muscle pain, rash, and changes in the menstrual cycle are also possible.
For the study, Steves and his colleagues used the UK-based ZOE COVID Symptom study app to collect data on 56,000 people infected with the Omicron strain. They were compared to more than 41,000 people infected with the Delta strain.
The result: The odds of having long COVID were 20% to 50% lower with Omicron than with Delta. The probabilities depended on the patient’s age and the time since vaccination.
Infectious disease expert Dr. Marc Siegel, a clinical professor of medicine at NYU Langone Medical Center in New York City, said long COVID is probably more common than you think.
"[Omicron] doesn’t cause as many deep lung infections, but it’s also true that there is immune protection from the vaccine and from previous infections to some extent," he said.
It follows that if the cases are less severe, there won’t be COVID for as long, said Siegel, who reviewed the findings.
"That’s my personal experience," he said. "In my practice, I never see anyone with loss of smell and taste again."
Still, Siegel predicts that COVID may become a permanent part of the landscape, like the flu.
"We’re still seeing illnesses and hospitalizations, but now we’re seeing a lot more illnesses than hospitalizations," he said. "I think that’s where we’re headed with this. I can’t be sure, but I think we’re headed toward a semi-permanent phase of persistent disease, but with less severe outcomes."
He stressed that having had COVID doesn’t mean you won’t get it again, because immunity from the infection appears to be short-lived. And breakthrough cases are possible even if you are vaccinated, although they are likely to be less severe than if you were not, Siegel said.
“Don’t count on prior infection to fully protect you and don’t count on a vaccine to fully protect you, but get as much immunity as you can,” he said.
It’s reassuring to know that Omicron appears to cause fewer symptoms in the long term, Siegel said.
"Note that Omicron causes fewer, but not zero, symptoms in the long term," he emphasized. “We need to continue to be aware of this virus and be cautious about it.”
The new findings were published in The Lancet .
