Dec. 22, 2021 -- A study conducted in the United Kingdom says there’s no evidence the Omicron variant causes less severe reactions than the Delta variant.
“The study finds 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,” says a blog post by researchers from the U.K.’s Imperial College London. “However, hospitalization data remains very limited at this time.”
Researchers looked at data gathered by the U.K. Health Security Agency and the U.K.’s health service for COVID cases confirmed by PCR tests between Nov. 29 and Dec. 11.
Researchers estimate the risk of reinfection by Omicron is 5.4 times greater than for the Delta.
“This implies that the protection against reinfection by Omicron afforded by past infection may be as low as 19%,” the blog said, adding that researchers estimated protection would be between 0-20% after two doses of vaccine and would be 55-80% after a booster shot.
“This study provides further evidence of the very substantial extent to which Omicron can evade prior immunity given by both infection or vaccination. This level of immune evasion means that Omicron poses a major, imminent threat to public health.” wrote Professor Neil Ferguson, the leader of the research team.
“Quantifying reinfection risk and vaccine effectiveness against Omicron is essential for modelling the likely future trajectory of the Omicron wave and the potential impact of vaccination and other public health interventions,” Professor Azra Ghani of the Imperial College London wrote in the blog post.
There were only 24 known cases of hospitalization caused by Omicron, the study said, meaning more research will be needed in that area.
Health authorities in the United Kingdom worry that Omicron cases will overwhelm hospitals because the variant is spreading so fast and Omicron cases are doubling every two days.
“Whatever the eventual percentage of people with Omicron who will need NHS care, the absolute number seeking care will also double every two days,” Christina Pagel, director of UCL’s Clinical Operational Research Unit, wrote in an opinion piece for TheGuardian.
“So the question is not whether it will be bad for the NHS, but whether it will be just dreadful or catastrophic.”