A recently published study conducted by the Imperial College in London has raised doubts surrounding the speculation that the Omicron variant of the coronavirus may be milder than its predecessor, Delta. According to researchers, there is no evidence (as of yet) that Omicron is less severe or lethal than Delta and that it is difficult to compare two strains of the same virus.
Two doses of AstraZeneca or Pfizer vaccines only afforded 20% protection against the highly mutated strain, the non-peer reviewed study concluded. This was in line with natural immunity; a third dose however increased protection up to 55-80% in symptomatic cases making booster doses of the vaccine an important factor in combating the virus.
"Risk of reinfection with the Omicron variant is 5.4 times greater than that of the Delta variant. This implies that the protection against reinfection by Omicron afforded by past infection may be as low as 19%," the Imperial College said in a statement. Such This level of immune evasion means that Omicron poses a major, imminent threat to public health, British epidemiologist Professor Neil Ferguson was quoted as saying.
The Imperial College London team analyzed all the PCR tests of confirmed Covid cases in England between November 29 and December 11, making it one of the most expansive examinations yet on Omicron's potential to evade the body's defences. The study looked at growth, population distribution and immune escape of the variant in England.
The results were based on the proportion of people testing positive who had symptoms or went to the hospital. Just how severe Omicron cases will be remains unclear, adding it is too soon to say how hospitalisations will play out in the UK.
The statement from the Imperial College quoted Professor Azra Ghani from Imperial College London, who said that more data was required to model the virus' trajectory to aid healthcare system.
"Quantifying reinfection risk and vaccine effectiveness against Omicron is essential for modelling the likely future trajectory of the Omicron wave and the potential impact of vaccination and other public health interventions," said Professor Ghani.