Omicron less efficient at attacking lungs and causing severe disease, UK study suggests

19 December 2021, 10:53 | Updated: 7 June 2023, 08:56

UK research has suggested Omicron might be less efficient at attacking the lungs than earlier Covid-19 variants.

The research found the same mutations that might make it able to evade immunity may also reduce how well it can replicate in the lungs and cause severe disease.

The study by the Cambridge Institute of Therapeutic Immunology and Infectious Disease looked at Omicron's mutations on the virus's spike protein.

"These observations highlight that Omicron has gained immune evasion properties whilst compromising on properties associated with replication and pathogenicity," the study's abstract stated.

Read more: Omicron: Tougher restrictions needed to stop hospital admissions soaring, scientists warn

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However one of the study's leaders said Omicron could still represent a "major public health challenge" because of its rapid spread and its potential to avoid vaccine or natural immunity.

Ravi Gupta, a professor of clinical microbiology at Cambridge and also a Sage member, tweeted: "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 a thread summarising the study's results, he added: "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."

It comes after advisory group 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.

The rapid spread of the new variant resulted in a major incident being declared in London on Saturday, partially due to the 'incredibly worrying' number of frontline staff who were off work with the virus.

The declaration of a major incident will allow authorities to work together to reduce resultant disruption to these services, and allow more time to give out booster jabs, the mayor's office said.

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"The surge in cases of the Omicron variant across our capital is hugely concerning, so we are once again declaring a major incident because of the threat of Covid-19 to our city," said Sadiq Khan.

"The Omicron variant has quickly become dominant with cases increasing rapidly and the number of patients in our hospitals with Covid-19 on the rise again.

"We are already feeling the impact across the capital and while we are still learning about this variant, it's right that London's key agencies work closely together to minimise the impact on our city, including helping to protect the vital vaccination programme."

Major incident declared in London amid Omicron spread

Omicron has already caused restrictions to tighten across Europe, with the Netherlands entering a strict lockdown from Sunday.

Schools, universities, and all non-essential stores, bars and restaurants in the Netherlands will be closed, prime minister Mark Rutte said Saturday night.

Read more: Covid: Netherlands announces strict lockdown to curb spread of Omicron

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Residents will only be permitted two visitors except for Christmas and New Year's, when four will be allowed, he said.

France, Cyprus, Austria and Germany have all tightened travel restrictions in recent days, and Denmark closed theatres, concert halls, amusement parks and museums.