Some experts are warning against writing off the omicron variant as milder than other variants, and preliminary findings from the U.K. suggest it appears no less severe than delta.
An Imperial College London study assessed data from the U.K. Health Security Agency and U.K. health service for all PCR-confirmed COVID-19 infections in the area from Nov. 29-Dec. 11. The data included only 24 hospitalizations of patients suspected of having the omicron variant and has not been peer reviewed.
The study found hospitalization and asymptomatic infection indicators were not significantly associated with omicron, suggesting limited changes in severity compared with delta. The study authors also estimate the risk of COVID-19 reinfection with the omicron variant is 5.4 times higher than that of delta, suggesting low remaining levels of immunity from previous infection.
"This study provides further evidence of the very substantial extent to which omicron can evade prior immunity given by both infection or vaccination," Dr. Neil Ferguson, a professor and epidemiologist at Imperial College London, said in a Dec. 17 statement. "This level of immune evasion means that omicron poses a major, imminent threat to public health."
Recently, many health officials — including Soumya Swaminathan, MD, chief scientist for WHO, and former FDA Commissioner Scott Gottlieb, MD, — have said it's still too early to tell if the omicron variant is milder than other strains, The Hill reported Dec. 20.