The Omicron variant would likely be capable of causing a new wave of coronavirus infections that could be even bigger than previous waves, Government scientists have warned.
The extraordinary meeting of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) subgroup on Sars-CoV-2 variant B.1.1.529 concluded that, if introduced into the UK, the variant would be able to initiate a new wave of infections.
A note of the meeting on November 25, was released by the Scientific Advisory Group for Emergencies (Sage) on Friday.
In it the scientists conclude: “We cannot exclude that this wave would be of a magnitude similar, or even larger, than previous waves.”
They continue: “Although data on disease severity associated with B.1.1.529 are not yet available, a large wave of infections will be accompanied by a wave of severe cases and the subgroup cannot rule out that this may be sufficient to overwhelm NHS capacity.”
According to the scientists, it is highly likely that omicron is a “fit” virus that is undergoing extensive community transmission in South Africa, and possibly elsewhere.
They say there is currently insufficient data to make any comments on disease severity associated with the variant.
And whilst the effect of the mutations on vaccine efficacy against severe disease is unknown, it is possible that efficacy against severe disease could be reduced, according to the scientists.
Minutes of a Sage meeting held on November 29 note that it is highly likely Omicron can escape immunity to some extent, but it is not yet clear how much.
The evidence comes from the number of reinfections already seen, and from the mutations in the variant that are either already known to be associated with immune escape, or which are found in areas that structural studies suggest will affect antibody binding.
Government scientists also note: “There is likely to be a greater reduction in protection conferred by previous infections or vaccines against infection than against severe disease (high confidence).”
But they add that it is not yet know to what extent protection from natural infection or vaccination will be affected, or how this may vary depending on the type of vaccine.
The Sage scientists warn: “Even if there continues to be good protection against severe disease for individuals from vaccination (including boosters), any significant reduction in protection against infection could still result in a very large wave of infections.
“This would in turn lead to potentially high numbers of hospitalisations even with protection against severe disease being less affected.
“The size of this wave remains highly uncertain but may be of a scale that requires very stringent response measures to avoid unsustainable pressure on the NHS.
“If vaccine efficacy is substantially reduced, then a wave of severe disease should be expected.”
They add: “It is important to be prepared for a potentially very significant wave of infections with associated hospitalisations now, ahead of data being available.”
Sage said its advice on measures to reduce transmission remains highly relevant, including but not limited to advice around ventilation, face coverings, hand hygiene, reducing contacts, vaccination certification, and the importance of effective testing, contact tracing and isolation.
They scientists say colder weather is likely to affect natural ventilation levels, as windows are less likely to be opened.
And they report, with low confidence, that there are some very preliminary indications Omicron might show more airborne transmission.
According to the minutes: “Even if measures are introduced immediately, there may not be time to fully ascertain whether they are sufficient before decisions are needed on further action.
“The situation could develop quickly over the coming weeks and decision-makers may need to act while there is still a high level of uncertainty including considering the potential need for stringent response measures.”
The scientists say evidence suggests measures could be reintroduced with expectation of a similar level of adherence as has been seen in the past if messaging has a clear rationale and there is coherence between messaging and policy.
“Early communication of risk and potential decisions would allow people to plan accordingly, and in turn increase levels of adherence,” the scientists say.