Omicron infections appear no less severe than Delta
Omicron infections no less severe based on early UK data
Infections caused by the Omicron variant of the coronavirus do not appear to be less severe than infections from Delta, according to early data from the UK.
Researchers at Imperial College London compared 11,329 people with confirmed or likely Omicron infections with nearly 200,000 people infected with other variants. So far, according to a report issued ahead of peer review and updated on Monday, they see "no evidence of Omicron having lower severity than Delta, judged by either the proportion of people testing positive who report symptoms, or by the proportion of cases seeking hospital care after infection."
For vaccines available in the UK, effectiveness against symptomatic Omicron infection ranged from 0% to 20% after two doses. The report also estimated that after taking individual risk factors into account, the odds of reinfection with Omicron are 5.4 times greater than for reinfection with Delta. A study of healthcare workers in the pre-Omicron era estimated that a prior SARS-CoV-2 infection afforded 85% protection against a second infection over 6 months, the researchers said, while "the protection against reinfection by Omicron afforded by past infection may be as low as 19%."