According to a report by a team of researchers at King’s College London (KCL), the prevalent Omicron COVID-19 strain in winter 2021 was less likely to cause long-term symptoms, or ‘long COVID’.
The investigation has been published in The Lancet and included data gathered by the team from nearly 100,000 people who recorded their COVID-19 symptoms on an app.
It was noted that just over 4% of individuals infected in the Omicron wave had recorded long COVID symptoms versus the 10% of individuals infected in the earlier Delta wave of the pandemic. However, given that many more people were infected during the Omicron wave, the total was higher.
Although many who catch COVID-19 will not become severely ill, and may see their condition improve relatively quickly, others have experienced long-term problems post-recovery from the original infection, despite experiencing a less serious case of the illness initally.
As a condition, long COVID is unexplored territory and presently, there is no internationally-agreed definition, resulting in a lack of understanding surrounding estimates of how common it is, or what the main symptoms are.
For health professionals, guidance refers to symptoms that continue for over 12 weeks which cannot be explained by another cause, and The Lancet research included reported symptoms lasting for four weeks or more.
According to the NHS, symptoms can include extreme fatigue, a shortness of breath, chest pain or tightness, problems with memory and concentration, noticeable changes to taste and smell and joint pain.
A range of other symptoms may also be present, as suggested in patient surveys, including gut issues, insomnia and vision changes.
The researchers at KCL tried to account for other variables, which included when someone had been vaccinated against COVID-19, although it is impossible to be certain that the difference between variants caused the difference in long COVID numbers.
It has been estimated by officials that long COVID has impacted at least two million people in the UK, with the estimate prior to the Omicron surge being around 1.3 million.
Lead researcher Dr Claire Steves said: “The Omicron variant appears substantially less likely to cause long COVID than previous variants – but still, one out of every 23 people who catches COVID-19 goes 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.”