The Omicron coronavirus variant is less likely to cause long Covid than the Delta strain, new research suggests. The study found the odds of experiencing long Covid were between 20% and 50% lower during the Omicron period versus the Delta period, depending on age and time since vaccination.
The analysis was conducted by researchers from King’s College London using data from the Zoe Covid Symptom study.
Lead author Dr Claire Steves, from King’s College London, said: “The Omicron variant appears substantially less likely to cause long Covid than previous variants but still one in 23 people who catch Covid-19 go on to have symptoms for more than four weeks. Given the numbers of people affected it’s important that we continue to support them at work, at home and within the NHS.”
The analysis showed that 4.4% of Omicron cases were long Covid, compared to 10.8% of Delta cases. However, the absolute number of people who had long Covid was higher in the Omicron period because of the vast numbers infected with the variant from December 2021 to February 2022.
The Office for National Statistics estimates the number of people with long Covid actually increased from 1.3 million in January 2022 to two million as of May 1, 2022. Long Covid is defined by the National Institute for Health and Care Excellence (Nice) guidelines as having new or ongoing symptoms four weeks or more after the start of disease.
Symptoms can include fatigue, shortness of breath, loss of concentration and joint pain. As well as affecting day-to-day activities, for some people the condition can be severely limiting.
The study identified 56,003 UK adults who tested positive between December 20 last year and March 9 this year, when Omicron was the dominant strain. Researchers compared these to 41,361 cases first testing positive between June 1 and November 27 last year, when the Delta was the dominant variant. The analysis is published in a letter to The Lancet.