The omicron variant of COVID-19 shows no signs of being less severe than the delta variant, according to a new study in the United Kingdom.

Researchers with Imperial College London, who analyzed PCR test-confirmed COVID-19 cases in England between Nov. 29 and Dec. 11, said their endeavor found "no evidence of Omicron having lower severity than Delta," judged by looking at "either the proportion of people testing positive who report symptoms, or by the proportion of cases seeking hospital care after infection."

The omicron variant, first detected in South Africa last month, is quickly spreading across the planet and is being associated with case hot spots in crowded places such as New York City, prompting a new wave of restrictions.

Early research suggested that the omicron variant was more transmissible but less severe than delta, which became the dominant strain worldwide this summer. Delta is twice as contagious as the prior variants and some data suggest it can cause more severe illness than previous variants in unvaccinated people, according to the Centers for Diseases Control and Prevention.


The Imperial College London team also reported findings that show "the risk of reinfection with the Omicron variant is 5.4 times greater than that of the Delta variant. This implies that the protection against reinfection by Omicron afforded by past infection may be as low as 19%."

The work has not yet been peer-reviewed, but it was presented in the latest report from the World Health Organization's Collaborating Center for Infectious Disease Modeling within the MRC Center for Global Infectious Disease Analysis, Jameel Institute, Imperial College London, according to an online post on Friday.

More than 273 million cases of COVID-19 have been reported around the world since the start of the pandemic, and more than 5.3 million deaths have been associated with it, according to data posted by Johns Hopkins University. More than 200 million people have been fully vaccinated in the United States, and roughly 58 million have received a booster shot, according to the CDC.

The work of the Imperial College London's COVID-19 team has been the subject of scrutiny and controversy. Others have criticized its initial projections of the coronavirus's toll, which included 2,200,000 deaths in the U.S. without a coordinated policy response. Its leader, Neil Ferguson, quit his role advising the British government after it emerged that he had been visited by a woman at his home during a lockdown he advised.

A "pre-print" from Columbia University said the omicron variant of COVID-19 is proving to be "markedly resistant" to vaccines.

"A striking feature of this variant is the large number of spike mutations 31 that pose a threat to the efficacy of current COVID-19 vaccines and antibody therapies," according to an abstract from more than 20 scientists with Columbia University and the University of Hong Kong.

Even for booster shots, which health officials highly recommend for everyone 16 years and older in the United States, the study warned they "may not adequately protect against Omicron infection," though it still advises people to get one.


Dr. Anthony Fauci, President Joe Biden's chief medical adviser, this week advocated the importance of people not only getting vaccinated but boosted as well as a means to offer more protection against omicron.

"Our booster vaccine regimens work against omicron. At this point, there is no need for a variant-specific booster," Fauci said during a White House briefing on Wednesday.

Ferguson, a professor at Imperial College London who helped lead the new study, stressed that "it's very early days" in terms of examining omicron.

“We should have data within a week to make a more definitive judgment on relative severity," he added.