Too soon to say if Omicron more transmissible than Delta: WHO

The World Health Organization (WHO) does not yet have enough data on the new Omicron variant of the coronavirus to say if it is more transmissible than the Delta variant, an official said on Wednesday, almost a month after South Africa first raised the alarm about its emergence.

“We have not seen this variant circulate for long enough in populations around the world, certainly in vulnerable populations,” said the WHO’s technical lead on COVID-19, Maria van Kerkhove, in a briefing with media.

She said the data on the new variant, first identified in southern Africa and Hong Kong in November, was still “messy” as countries reported its arrival and spread.

Questions about Omicron’s virulence are at the heart of scientific and political debate in many countries, as governments grapple with how to respond to the spread of the variant while researchers race to understand it.

A South African study also suggested reduced risks of hospitalisation and severe disease in people infected with the Omicron coronavirus variant versus the Delta one, though the authors say some of that is likely due to high population immunity.

The study, which has not been peer-reviewed, found that people diagnosed with Omicron in South Africa between Oct. 1 and Nov. 30 were 80% less likely to be admitted to hospital than those diagnosed with another variant in the same period.

Among patients admitted in that period, those with Omicron had a similar chance of developing severe disease as those with other variants.

However, the study found that people who were hospitalised with Omicron in October-November were 70% less likely to develop severe disease than those admitted with Delta between April and November.

Results of a major study by Imperial College London released last week showed there was no sign that Omicron was milder than Delta, although data on hospitalisations remains very limited. It has not been peer reviewed and published in a medical journal.