The omicron variant of SARS-CoV-2 has spread rapidly across the world, out-competing former variants soon after it was first detected in November 2021. According to the Our World in Data COVID-19 database, in Europe, the number of confirmed cases reported between December 2021, and March 2022 has exceeded all previously reported cases.
Overall, the omicron variant appears to cause less severe acute illness than previous variants, at least in vaccinated populations.
Another concern regarding COVID-19 has been the development of long COVID, which includes symptoms such as chronic fatigue, loss of smell, hearing loss, muscle pain, brain fog, and memory loss.
Omicron Infection Less Likely to Cause Long COVID
In a recently published study, researchers from King’s College London compared the risk of developing long COVID from two different SARS-CoV-2 variants. Their results appear in the journal The Lancet.
For the study, the researchers identified 56,003 UK adults first testing positive between Dec 20, 2021, and March 9, 2022, who satisfied the inclusion criteria. These cases are hereafter referred to as omicron cases as more than 70% of UK cases were estimated to be attributable to the omicron variant during that time.
They also identified 41,361 UK adult cases testing positive between June 1, 2021, and November 27, 2021, referred to as delta cases as more than 70% of cases were attributable to the delta variant.
The team found that people who experienced SARS-CoV-2 infections with the Omicron variant were less likely to have long COVID symptoms compared to those who had the Delta variant. The researchers found that 4.4% of Omicron cases experienced long COVID symptoms, compared to 10.8% of Delta variant cases.
According to their results, those with Omicron infections were 20-50% less likely to develop long COVID symptoms than those with the Delta variant.
Michela Antonelli, et al. Risk of long COVID associated with delta versus omicron variants of SARS-CoV-2. 2022. The Lancet. DOI:https://doi.org/10.1016/S0140-6736(22)00941-2