Two new preprint papers add to growing evidence that the Omicron coronavirus variant may be less likely to cause severe disease and hospitalization compared to the Delta variant.
Omicron is associated with a two-thirds reduction in the risk of Covid-19 hospitalization compared with Delta, suggests one study, released online Wednesday as a working paper by researchers at the University of Edinburgh in the United Kingdom. That research was based out of Scotland.
The other paper, posted Tuesday to the online server medrxiv.org, suggests that people with Omicron infections have had 80% lower odds of being admitted to the hospital compared with Delta infections. But once a patient was hospitalized, there was no difference in the risk of severe disease, according to that research, based out of South Africa.
Both studies include preliminary data and have not yet been published in a peer-reviewed journal.
The study out of Scotland included data on 23,840 Omicron cases and 126,511 Delta cases, from Nov. 1 to Dec. 19. The researchers – from the University of Edinburgh, University of Strathclyde and Public Health Scotland – took a close look at the health outcomes among those Omicron infections compared with Delta infections. There were 15 hospital admissions among those with Omicron infections and 856 hospital admissions among Delta.
“Although small in number, the study is good news. The two thirds reduction in hospitalisation of double vaccinated young people compared to Delta indicates that Omicron will be milder for more people,” James Naismith, director of the Rosalind Franklin Institute and professor of structural biology at the University of Oxford, who was not involved in either study, said in a written statement distributed by the UK-based Science Media Centre on Wednesday.
The researchers found that the proportion of Omicron cases that were likely reinfections in people who have had Covid-19 before was more than 10 times that of Delta. The data also showed that having received a third dose of vaccine, or booster shot, was associated with a 57% reduction in the risk of symptomatic Omicron infection when compared with being at least 25 weeks out from completing a second dose.
“These early national data suggest that Omicron is associated with a two-thirds reduction in the risk of COVID-19 hospitalisation when compared to Delta. Whilst offering the greatest protection against Delta, the third/booster dose of vaccination offers substantial additional protection against the risk of symptomatic COVID-19 for Omicron,” the researchers wrote in the paper.
Read the full story on the studies here.
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