11:31 a.m. ET, December 13, 2021
Overall risk from Omicron remains high as many questions remain, WHO says
From CNN's Naomi Thomas
This photograph taken on December 7, 2021 shows a sign of the World Health Organisation (WHO) at their headquarters in Geneva.
(Fabrice Coffrini/AFP/Getty Images)
The overall risk from the Omicron variant remains high, and more information is still needed about the variant, the World Health Organization said in a technical brief about the variant, published Friday.
“The overall risk related to the new variant of concern Omicron remains very high for a number of reasons,” the technical brief said. “First, the global risk of COVID-19 remains very high overall, and second, preliminary evidence suggests potential humoral immune escape against infection and high transmission rates, which could lead to further surges with severe consequences. Our understanding is still evolving, and the risk assessment will be updated as more information becomes available.”
The overall threat of Omicron is dependent on three key factors, WHO says:
- How transmissible the variant is
- How well vaccines and prior infection prevent against infection, transmission, clinical disease and death
- How virulent Omicron is compared to other variants
WHO says Omicron appears to have a growth advantage over Delta, adding that it is spreading faster than Delta in South Africa, where there was low Delta circulation. But, it also appears to spread faster in countries with high incidence of Delta, based on current limited evidence, the organizations says.
“Given the current available data, it is likely that Omicron will outpace the Delta variant where community transmission occurs,” WHO says.
There is limited data on the clinical severity and vaccine efficacy or effectiveness to Omicron, WHO says.
On clinical severity, WHO says that while preliminary findings suggest it may be less severe than Delta, and cases reported so far who have been mild or asymptomatic, but “it remains unclear to what extent Omicron may be inherently less virulent.”
More data is needed to understand the severity profile.
For vaccine efficacy and effectiveness, WHO says there are limited available data and no peer-reviewed evidence. Preliminary evidence and the altered antigenic profile of Omicron’s spike protein also suggests that there may be a reduction in vaccine efficacy against infection and transmission. There is also preliminary evidence which suggests that reinfection in South Africa has increased, which may be associated with humoral immune evasion.
The accuracy of PCR and antigen-based rapid diagnostic tests doesn’t appear to be influenced by Omicron, WHO says.
On treatments, WHO says that therapeutic interventions that target the host response – corticosteroids, for example — should still be effective. Monoclonal antibodies, however, will have to be tested individually.
WHO gives a number of priority actions for its member states. These include enhanced surveillance, laboratory testing for Omicron, vaccination, a risk-based approach in adjusting international travel measures, public health and social measures, health care system readiness and risk communication and community engagement.