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expert reaction to UKHSA updated report on Omicron hospitalisation and vaccine effectiveness analysis

The UK Health Security Agency (UKHSA) has published the latest technical briefing looking at SARS-CoV-2 variants of concern and variants under investigation in England.


Prof Peter Openshaw, Professor of Experimental Medicine, Imperial College London, said:

“This is really important new data that again confirms the vital importance of getting third dose (booster) vaccines.  Omicron is a very highly infectious variant and even if you think you can keep yourself safe by reducing contacts with others, it’s now very unlikely that you can escape infection forever.  This study adds to the now overwhelming evidence that three doses of vaccine provides good protection against severe COVID-19 caused by Omicron.  It’s a bit early to be sure, but it seems possible that some additional boosters will be needed.  Remember that we need 4 doses of vaccine to be fully protected against whooping cough or polio.  The same may be true of coronavirus, but we need to wait and see.”


Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, Respiratory Sciences, University of Leicester, said:

“This latest update just reinforces what we have been seeing – that Omicron is more vaccine escape capable but causes fewer hospitalisations.

“There is significant under ascertainment because most PCR testing use different assays that do not target the S gene – but the overall findings with these other assays (mostly in hospital labs) are likely to be similar.

“The message is the same – that boosters help to overcome some of this vaccine escape and will reduce infection/reinfection rates, hospitalisations and onward transmission risks – but the more rapid spread of Omicron may lead to exacerbations of other chronic conditions that may still lead to increased hospitalisations – just like we see with other seasonal respiratory viruses, including flu.

“Yet, we are seeing a milder but more transmissible infection with Omicron – and, personally, I am still hopeful that the virus will eventually become more like the other common cold coronaviruses – perhaps over the next 1-2 years – making repeat vaccination, masking and social distancing necessary then for only the most vulnerable – similar to what we do for flu each year.”


Dr Raghib Ali, Senior Clinical Research Associate, MRC Epidemiology Unit, University of Cambridge, said:

“The latest UKHSA report provides an important update on Omicron severity and the first estimates of vaccine effectiveness against hospital admission.

“The analysis based on half a million cases shows that the risk of hospital admission is about one third of that of delta and that three doses reduces the risk of hospitalisation by 81% compared to the unvaccinated.  A second analysis on 200,000 cases showed vaccine effectiveness for 3 doses against hospitalisation was 88%.

“Given the very high uptake of the booster in the highest risk groups, these results are encouraging.

“It is also reassuring to see preliminary analyses showing a lower risk of hospital admission in school age children (less than half) for Omicron compared to Delta.

“However, given the very high and increasing number of cases, especially in the over 60s, it is essential for everyone to keep following the public health guidance to help reduce pressure on the NHS in the coming weeks.”


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

“Today sees an updated report on vaccine induced protection against symptomatic illness and hospitalisation following infection with the omicron variant using data available up to 29 December 2021.  Unsurprisingly, given the high level of vaccination in the UK population, at this point, 3/4 of the patients admitted to hospital have received at least one dose of vaccine.  However, the level of protection against both symptomatic illness and need for hospital care if infected varies according to the completion of and duration since completion of a primary course of vaccine.  As already reported, protection against symptomatic disease is lower following infection with the omicron than the delta variant, with protection against symptomatic illness after omicron variant infection being almost completely lost 6 months following completion of a primary course with any vaccine type, but restored to 60% or higher within 2 weeks of receipt of a booster shot.  Fortunately, despite reduced protection from symptomatic illness, completion of a primary vaccine course in the previous 6 months confers 72% protection from hospitalisation following omicron variant infection, rising to 88% within 2 weeks following receipt of a booster shot.

“As the main reason for vaccination is to protect against severe illness requiring hospitalisation, everyone not yet vaccinated or that has not completed their primary course would be well advised to come forward for vaccination, while those fully vaccinated should come forward for their booster shot.

“The current dataset does not permit an assessment of the severity of illness among those hospitalised following infection with the omicron variant and we will need to wait until later in the New Year for this additional data, which, alongside case hospitalisation rate, will be critical to healthcare service planning over the early months of 2022.”



‘SARS-CoV-2 variants of concern and variants under investigation in England; Technical briefing: Update on hospitalisation and vaccine effectiveness for Omicron VOC-21NOV-01 (B.1.1.529), 31 December 2021’ was published by the UKHSA on Friday 31 December 2021.



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



Declared interests

Prof Peter Openshaw: “Peter Openshaw has served on scientific advisory boards for Janssen/J&J, Oxford Immunotech, GSK, Nestle and Pfizer in relation to immunity to viruses (fees paid to Imperial College London).”

Dr Raghib Ali: “No CoI.”

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).”

None others received.

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