The omicron variant is less likely to cause long COVID-19 compared to the coronavirus's original strain, according to a Swiss study of 1,201 healthcare workers.
The research is awaiting peer review, but the healthcare workers infected with the original SARS-CoV-2 strain were 67 percent more likely to have persistent symptoms, or long COVID, than those who did not get COVID-19. Those infected with the omicron variant were no more likely to report long COVID than those not infected.
Another finding was that having omicron after an original infection did not carry a greater risk of long COVID or fatigue than one infection with the original strain.
"With the emergence of omicron, its ongoing global dominance and the accompanying explosion of infections, it is vital to find out more about who is at risk of long COVID and why," Carol Strahm, MD, who works at Cantonal Hospital St. Gallen in Switzerland, said in a March 8 news release from the American Association for the Advancement of Science.
"We can only speculate as to why this was," Dr. Strahm added. "It's probably due to a combination of the omicron variant being less likely to cause severe illness than the [original] virus — we know that long COVID is more common after severe illness — and immunity acquired through previous exposure to the virus through, for example, a sub-clinical infection without seroconversion."
The researchers will present the study's results at the European Congress of Clinical Microbiology & Infectious Diseases in mid-April.