Omicron is less likely to cause a long COVID, the study finds

People walk along a platform at Kings Cross station during the morning rush hour amid the COVID-19 outbreak in London, December 1, 2021. New study shows Omicron is less likely to cause long-term COVID compared to Delta variant. (Henry Nicholls, Reuters)

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LONDON – The Omicron variant of the coronavirus is less likely to cause a long COVID than previous variants, according to the first peer-reviewed study of its kind from the United Kingdom.

Researchers at King’s College London, using data from the ZOE-COVID symptom study app, found that the likelihood of developing long COVID after infection was 20% to 50% lower during the Omicron wave in the UK than at Delta. The number varied depending on the age of the patient and when they were last vaccinated.

Long COVID, which includes persistent symptoms ranging from fatigue to “brain fog,” can be debilitating and last for weeks or months. It is increasingly recognized as a public health concern, and researchers have struggled to determine whether omicron poses as great a risk of long-COVID as previously dominant variants.

The King’s College London study is believed to be the first academic research to show that Omicron does not pose as much of a risk for long-term COVID-19, but that does not mean that the number of patients with long-term COVID-19 is going down, said the team.

While the risk of long COVID was lower during omicron, more people were infected so the absolute number of sufferers is now higher.

“It’s good news, but please don’t shut down any of your long COVID services,” said lead researcher Dr. Claire Steves told Reuters and appealed to healthcare providers.

Britain’s Office for National Statistics said in May that 438,000 people in the country have long COVID after Omicron infection, accounting for 24% of all long COVID patients.


It’s good news, but please don’t shut down any of your long COVID services.

-DR. Claire Steves, Principal Investigator


It also said the risk of persistent symptoms after Omicron was lower than with Delta, but only for double-vaccinated people. It found no statistical difference for those who were triple-vaccinated.

In King’s Research, 4.5% of the 56,003 people screened during the peak of omicron, December 2021 to March 2022, reported long COVID. This compares to 10.8% of 41,361 people during the delta wave from June to November 2021. Vaccinated and unvaccinated people were not compared.

While the study, published Thursday in The Lancet magazine, compared Delta and Omicron, Steves said previous work had shown no significant difference in long-term COVID risk between other variants.

More work is needed to determine why Omicron may have a lower long-term risk of COVID, the team added.

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