A senior scientist warned that people should not assume that Covid will become a milder disease, as the threat of the Omicron coronaviruses variant will not be clear until the end of December.
Prof Neil Ferguson, head of the disease outbreak analysis and modelling group at Imperial College London, told MPs on Wednesday that evolution would drive Covid to spread more easily, but that it might not become less dangerous.
Ferguson told the Commons science and technology committee that most of the transmission had already happened. The virus wants to get out into the environment quickly. The virus doesn't care if that happens to kill someone 10 days later.
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How dangerous is the Omicron variant?
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Minutes from the New and Emerging Respiratory Virus Threats Advisory Group revealed that the experts urged UK ministers last week to take "early and robust actions" to limit the transmission of the Omicron variant.
The scientists noted that early analysis of the variant gave them enough worrying signals to recommend early and robust actions to prevent introduction and onward transmission.
The B. 1.1.529 variant was first detected in South Africa and has prompted the government to increase the pace of the booster vaccine programme.
South Africa and a number of other countries have been placed on the travel red list because of their proximity to positive Omicron cases.
The minutes of the meeting said that it was not certain how serious the health outcomes of the variant could be, but that a large wave of infections could overwhelm the health service. The group wants to make sure that vaccines and treatments are up to date.
The subgroup cannot rule out that a wave of severe cases may be enough to overwhelm the capacity of the health service.
The minutes of a meeting of the Scientific Advisory Group for Emergencies (Sage) were leaked and it was suggested that experts had called on the government to introduce pre-departure testing for travellers returning to the UK. The minutes of a meeting held on Monday show scientists saying such testing could be valuable.
Ferguson told the MPs that some viruses were not always as dangerous as they first appeared. He said that the Alpha and Delta variant caused more severe disease than their predecessors.
It is too early to say if Omicron will be more severe than previous strains, but Alpha has been more severe than the previous strain, a little in terms of severe outcomes counterbalanced by the fact that we
The trend we have seen so far is toward greater severity, not lesser severity, and fortunately countered by better treatments, that means people have a better chance of surviving severe Covid today than they did at the beginning of the epidemic.
Viruses can change as they replicate in bodies. Some of the mutations can improve the ability of the virus to spread. This could happen if a variant causes people to be infectious for longer or if it causes human cells to bind better.
The UK is a highly immune population and a variant can gain the upper hand if it makes it harder for the immune system to attack.
The Omicron variant is expected to be more transmissible and harder to recognise. The global effort to understand how well vaccines and immunity protect against the variant has been sparked by the concerns. Ferguson said it would take longer to understand the threat posed by Omicron because the first results are expected in the next week or two.
It took several weeks for epidemiologists to gather enough data to figure out how much more transmissible Alpha and Delta were.
It would take three to four weeks to get an indication of the vaccine's effectiveness. We have to be patient. It is likely to be at the end of this month.
