Omicron could have a less damaging effect on the lungs than the Delta variant of Covid-19, but even if that is the case, the extremely high transmissibility of the virus will still present a “major public health challenge”, a UK study has found.
Several experts say that even a less severe variant of Covid-19 could overwhelm hospitals, with disastrous consequences.
The new research by the Cambridge Institute of Therapeutic Immunology and Infectious Disease contradicts a study by Imperial College London, released on Friday, which said there was little evidence that Omicron caused less severe illness than Delta, which is globally dominant but expected to be overtaken by the new strain as the leading cause of illness.
The Cambridge Institute study said the distinct mutations in the Omicron variant’s spike protein, which make it able to avoid antibodies, may also reduce how it replicates in the lungs and causes severe disease.
“These observations highlight that Omicron has gained immune evasion properties while compromising on properties associated with replication and pathogenicity,” the study’s abstract stated.
Pathogenicity is defined as the ability of a virus to cause harm to the human body.
Study leader Ravi Gupta, a member of the Scientific Advisory Group for Emergencies (Sage) and professor of clinical microbiology at Cambridge, said there are still challenges ahead despite the seemingly positive findings.
He wrote on Twitter: “What does this all mean? Efficient infection of lung cells could correlate with severity of lung disease. Syncitia or fused cells are often seen in respiratory tissues taken following severe disease. Delta was very good at both, in contrast to Omicron. Further work is needed.
“In summary this work suggests that Omicron does appear to have become more immune evasive, but that properties associated with disease progression *may* be attenuated to some extent. The significant growth of Omicron nevertheless represents a major public health challenge.”
The study comes after Sage’s “situation update” said it is “almost certain that there are now hundreds of thousands of new Omicron infections per day” in England, prompting reports that tighter pandemic restrictions could be introduced after Christmas.