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expert reaction to modelling of growth, population distribution and immune escape of Omicron in England by Imperial College London

Modelling by Imperial College London looks at growth, population distribution and immune escape of the Omicron variant of SARS-CoV-2.

This Roundup accompanied an SMC Briefing.


Prof Deborah Dunn-Walters, Chair of the British Society for Immunology COVID-19 Taskforce and Professor of Immunology at the University of Surrey, said:

“The message from this study is clear – don’t think that if you’ve caught COVID before, you can’t fall ill with it again.  This preprint backs up previous studies that indicate reinfections are much more common with the Omicron variant as it appears to be able to more easily evade any prior immunity gained.

“Vaccination provides you with a safe and effective way to boost your immunity levels to COVID-19, and in particular to the Omicron variant, without falling ill with the disease.  This booster dose is particularly vital to get now as this research shows that three doses provides much better protection against Omicron than two vaccine doses.  With high levels of coronavirus now circulating in our communities, it’s really important that everyone gets their booster dose as soon as possible to maximise the level of protection they have against COVID-19.  However, we also need to remember that the immune response takes time to build after receiving the booster dose.  Therefore, a cautious approach to the number of people that you come into contact with is needed to make sure we all play our part in minimising the spread of COVID-19 this Christmas.”


Prof Penny Ward, Independent Pharmaceutical Physician, and Visiting Professor in Pharmaceutical Medicine at King’s College London, said:

“This second report from Imperial College uses real world data on infection with delta vs omicron variants to assess the level of protection afforded by vaccines vs infection and illness with the omicron variant compared to that caused by the delta variant.  It is notable that the majority of confirmed omicron infections reported in the dataset are from young adults, many of African descent, primarily in the London region, which is a pattern very different to that observed with delta variant infections.  In particular, the current clustering of cases of omicron infection in younger age adults, who are inherently less likely to be hospitalised or to die from COVID, limits the extent to which differences in severity of illness following the infection caused by these two variants can be assessed.

“Protection conferred by vaccine boosters against infection ranged from 55-80%, dependent on the vaccine effectiveness estimates for delta variant infection incorporated into the analysis.

“Notwithstanding the uncertainties in the information set caused by the uneven distribution of the variant currently, the rapid doubling time combined with reduced vaccine protection suggest, as the authors state, that ‘omicron poses an immediate and substantial threat to public health in England and more widely’.  In the absence of significant quantities of antiviral medications to use as an adjunct to vaccination across the whole high risk population only reducing social contact decreases the potential for infecting those at greatest risk.  Indeed, the public have already started to do this: let us hope their actions are successful and that this wave, which has risen very sharply in recent days, starts to decline quickly as Professor Whitty suggests it may.”



‘Report 49 – Growth, population distribution and immune escape of Omicron in England’ by Neil Ferguson et al. was posted online on Friday 17 December 2021. This work is not peer reviewed.



All our previous output on this subject can be seen at this weblink:



Declared interests

Prof Deborah Dunn-Walters: “None.”

Prof Penny Ward: “I am semi-retired, but I am owner/Director of PWG Consulting (Biopharma) Ltd a consulting firm advising companies on drug and device development. Between December 2016 and July 2019 I served as Chief Medical Officer of Virion Biotherapeutics Ltd, a company developing antiviral treatments for respiratory viral diseases. Previous employee of Roche, makers of tocilizumab (anti IL6 antibody) and CMO of Novimmune, makers of empalumab (anti IFN gamma antibody).”

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