No evidence Omicron cases less severe than Delta: Study

A previous Covid-19 recovery provides little shield against infection with the omicron variant, a research team from Imperial College London showed in a large study that underlines the importance of booster shots.

Having had Covid probably only offers 19% protection against omicron, the study showed on Friday. That was roughly in line with two doses of vaccine, which the team estimated were as much as 20% effective against omicron. Adding a booster dose helped dramatically, blocking an estimated 55% to 80% of symptomatic cases.

The Imperial College London team analyzed all the PCR test-confirmed Covid cases in England between November 29 and December 11, making it one of the most expansive examinations yet at omicron's potential to evade the body's defenses. The results were in line with the picture emerging of the variant's capacity to elude protection from previous infection or inoculation and spread faster than previous iterations of the virus.


There was no evidence of omicron cases being less severe than delta, based on the proportion of people testing positive who had symptoms or went to the hospital, the team said.

Just how severe omicron cases will be remains unclear. It's too soon to say how hospitalizations will play out in the U.K. Bloomberg