COVID-19 reinfection is over five times more likely with the Omicron variant than the Delta strain, according to a new study.
The highly contagious new variant evades immunity from past infection at a risk 5.4 times greater than Delta, according to a report that reviewed thousands of UK cases.
For the study, Imperial College London’s COVID-19 response team found that protection against the Omicron variant has fallen to a rate of 19 percent among people who have already had the virus.
By contrast, there was an 85 percent protection rate against the Delta variant over a six-month period, according to the study of more than 200,000 cases, which was published this week.
“This suggests relatively low remaining levels of immunity from prior infection,” the study concludes.
Researchers also reviewed hospital data and found the severity of the strain may be on a par with the Delta variant.
“Hospitalization and asymptomatic infection indicators were not significantly associated with Omicron infection, suggesting at most limited changes in severity compared with Delta,” the report notes, without elaborating.
That finding contradicted a study published by Hong Kong researchers this week that found Omicron likely leads to less severe infections than the Delta variant.
Overall, the study found that Omicron cases were rapidly spreading — doubling every two days in the weeks leading up to Dec. 11, when the study concluded.
Younger people, ages 18 to 29, along with people with “African ethnicity” in the London area, had significantly higher infection rates of Omicron relative to the Delta variant, the report states.
For the study, researchers reviewed genotype and viral load data associated with reinfections. They also looked at thousands of COVID-19 tests taken between Nov. 29 and Dec. 11 in England.