Some people infected with the Omicron variant have already had COVID twice before, new data shows.
A technical briefing on COVID released by the U.K. Health Security Agency on Thursday stated that there were “69 identified cases with Omicron as a third episode of infection” out of over 116,000 individuals with Omicron infections between November 1 and December 18.
Omicron appears able to reinfect some people who have already had COVID before, the report suggested. It said that 9.5 percent of the confirmed Omicron infections occurred in people who had had COVID before, but this figure was likely to be a substantial underestimate of the proportion of reinfections.
In addition, the report highlighted 290 cases where people caught Omicron just 60 to 89 days after previously being infected with COVID a first time.
The U.S. Centers for Disease Control and Prevention (CDC) states that cases of reinfection with COVID remain rare, but a recent report from Imperial College London (ICL) noted that the Omicron variant was associated with a more than 5-fold higher risk of reinfection compared to the Delta variant.
“This suggests relatively low remaining levels of immunity from prior infection,” it added.
It should be noted that cases of people catching COVID three times have been documented prior to the emergence of Omicron. Citing health officials, Minnesota news outlet Twin Cities Pioneer Press reported in November this year that thousands of Minnesotans had caught COVID multiple times and some three or more times—though it noted doctors were working to determine if any were duplicates.
In August, the CDC highlighted a report from Kentucky that suggested unvaccinated people were more likely to get reinfected with COVID than the vaccinated.
The report looked at Kentucky residents infected with COVID in 2020 and who were re-infected around May and June this year. It found that the residents who were not vaccinated had 2.34 times the chances of reinfection compared with those who were fully vaccinated.
“These findings suggest that among persons with previous SARS-CoV-2 infection, full vaccination provides additional protection against reinfection,” the report stated.
However, the study was carried out at a time before the Omicron variant had been found and may not be relevant to Omicron. Data has suggested that Omicron is more able to resist vaccines than the Delta variant.
Meanwhile, the Omicron variant has now been detected in every U.S. state with more people expected to get infected in gatherings ahead of the holidays.
Thousands of people in the country are reported to have been affected by travel disruption this week with airlines canceling dozens of flights due to the recent spike in Omicron cases.
In a statement reported by various news outlets, a United spokesperson said the variant had had a “direct impact on our flight crews and the people who run our operation.”