South African study suggests Omicron has a lower risk of hospitalisation than Delta
pharmafile | December 22, 2021 | News story | Research and Development |
A new South African study suggests that there are reduced risks of hospitalisation and severe disease in people infected with the Omicron COVID-19 variant than with Delta, according to Reuters. Authors of the study say that this could in part be due to high population immunity.
The study, not yet peer reviewed, aimed to assess the severity of disease by comparing data about Omicron infections in October and November, with data about Delta infections between April and November, all in South Africa.
The research was undertaken by a group of scientists from the National Institute for Communicable Diseases (NICD), and universities such as The University of the Witwatersrand and University of KwaZulu-Natal.
The study authors found the risk of hospital admission was approximately 80% lower for those infected with Omicron, compared to those infected with Delta. For hospitalised patients, the risk of severe disease was roughly 30% lower. Despite these findings, experts have warned against dismissing the Omicron variant as mild, as there is not yet enough validated evidence to support this hypothesis.
The authors wrote: “It is difficult to disentangle the relative contribution of high levels of previous population immunity versus intrinsic lower virulence to the observed lower disease severity.”
Paul Hunter, a professor of medicine at the University of East Anglia, identified an issue with the study – it compared Omicron data from one period with Delta data from an earlier period. “So even though cases of Omicron were less likely to end up in hospital than cases of Delta, it is not possible to say whether this is due to inherent differences in virulence, or whether this is due to higher population immunity in November compared to earlier in the year,” Hunter said.
Tedros Adhanom, director-general of WHO, emphasised that the threat of omicron should not be taken lightly, saying that: “Even if omicron does cause less severe disease, the sheer number of cases could once again overwhelm unprepared health systems.”
Lina Adams
