Researchers: Hong Kong University
What they did: The researchers exposed lung tissue in a laboratory to the original Covid strain that was identified in Wuhan last year, along with the two variants, to compare how the viruses behave after infection.
What they found: Omicron multiplies 70 times faster than Delta in the bronchus — tubes connecting the windpipe and lungs — but 10 times slower in the lungs than predecessors. The finding may explain why the mutant virus is spreading at a ferocious pace, and also lends weight to the theory it is milder than the past variants.
What it means: Higher viral loads nearer the throat means people are more likely to breathe out viral particles. Delta was found to duplicate much quicker in the lungs, where more of the virus can lead to the most severe illness. The finding may be the biological clue behind why doctors insist people infected with the strain only suffer cold-like symptoms.
Researchers: Washington University
What they did: Researchers assessed different parts of the lungs for mice infected with the Omicron variant as well as other strains of the virus including Delta.
What they found: Those infected with Omicron had less lung damage, lost less weight and were less likely to die than those that had other variants. It found mice infected with Omicron had a tenth less of the virus in their lungs compared to those with other variants.
What it means: Scientists said it adds to the growing body of evidence that Omicron manifests itself in the upper respiratory system.
Researchers: South Africa’s National Institute for Communicable Diseases
What they did: The researchers examined 10,547 people infected with Omicron and 948 non-Omicron infections.
What they found: 2.5 per cent of those infected with Omicron were hospitalised, compared to 12.8 per cent of those infected with other strains. The team said this equated to Omicron being 80 per cent less likely to lead to hospitalisation than Delta.
What it means: The researchers said it still doesn’t answer whether Omicron is intrinsically weaker than Delta. Built-up immunity from three previous waves of the virus and vaccines are believed to be doing most of the heavy lifting in keeping patients out of hospital this time around.
Researchers: Imperial College London
What they did: Researchers analysed data on 56,000 Omicron cases and 269,000 Delta cases in the first to weeks of December.
What they found: Those who catch Omicron are 15 to 20 per cent less likely to be admitted to hospital and 40 to 45 per cent less likely to spend a night or more in hospital than those who catch Delta.
What it means: The team said the findings can help other countries plan for Omicron waves.
Researchers: University of Edinburgh
What they did: The team tracked more than 150,000 patients diagnosed with Covid, including 22,000 Omicron cases, most of whom were aged under 65.
What they found: The number of Omicron patients who needed to be hospitalised was 68 per cent lower than the expected number of admissions for Delta cases. If Omicron was as severe as Delta they would have seen 47 admissions but they only recorded 15.
What it means: The finding adds to research the variant is less severe, but researchers cautioned the high number of Omicron cases could mean the NHS is overwhelmed with more patients than last winter.