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expert reaction to latest ONS COVID-19 Infection Survey, UK: 24 March 2023, which is the final weekly Infection Survey release

The Office for National Statistics (ONS) has released* the final COVID-19 Infection Survey data set.


Prof Sir David Spiegelhalter, Emeritus Professor of Statistics, University of Cambridge, said:

“The Covid Infection Survey has been an extraordinary achievement – since it was rapidly established in April 2020 it has provided vital evidence of great value both to national policy and international scientific understanding. I have been Chair of its Advisory Board, and so I would say that, wouldn’t I? But this is not just personal bias – there is a general consensus that the survey has been a world-leading demonstration of how health surveillance can best be done. A loyal cohort of participants have provided repeated swabs, blood tests and symptom data, giving unique information on infections, antibodies, long Covid, vaccine effectiveness, and so on – if we did not test people without symptoms, how else would be know how many were infected and yet symptom-free? All this data has not only generated evidence with immediate policy implications, but also numerous scientific papers for the international community. This has only been possible through intensive and generous collaboration between government agencies and academics – personally I have been amazed at the step-change to rapid analysis using the latest statistical methodology.

“It is expensive, and this has led to it being paused, but the participant group is not being disbanded and a survey should be able to ramp up when necessary. Meanwhile there are important lessons to be learned for future emergencies, both by us and every other country. The survey has been the envy of the world, and is a jewel in the crown of UK science.”


Prof Mark Woolhouse, Professor of Infectious Disease Epidemiology, University of Edinburgh, said:

“Data were always crucial for navigating the safest path through the Covid-19 pandemic. The ONS survey became one of the most trusted and reliable sources of surveillance data on levels of infection, providing key information that informed public health policy.

“The ONS performed active surveillance – making direct requests for individuals to participate – rather than the passive reporting that generated the daily case numbers shown on our TV screens during the height of the pandemic. Active surveillance is slower – the ONS survey was 1-2 weeks behind the daily numbers – but it is considered more representative of the true situation. An important observation was that ONS data consistently showed that the numbers of people infected were at least twice as high as was being reported at a national level.

“Despite its value to public health, active surveillance of this kind is expensive and is not routinely performed outside of a current health emergency. It is nevertheless vital that our capacity to perform this kind of survey is maintained and is available when needed.

“In 2020, the ONS survey was not launched until April 26th. By that date, the UK had been in lockdown for over a month and the first wave was already peaking. If the ONS survey had been rolled out much earlier – ideally in the first half of February – then we would have had more accurate information in those crucial early weeks and would likely have made better, and perhaps different, decisions about how to respond. We will need the capacity to ramp up active surveillance much more quickly when the next epidemic arrives. This must be a top priority for our pandemic preparedness planning.”




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


Declared interests

Prof Sir David Spiegelhalter: “I am Chair of the Advisory Board for Covid Infection Survey and a non-exec for the UK Statistics Authority, overseeing the work of ONS.”

Prof Mark Woolhouse: “No conflicts to declare.”

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