select search filters
briefings
roundups & rapid reactions
before the headlines
Fiona fox's blog
The number of people that have tested positive today for COVID-19 passed 60,000, and an ad hoc release from the Office for National Statistics (ONS) COVID-19 Infection Survey has estimated that around 2% of people in England currently has the virus (data from 27 December to 2 January).
Dr Amitava Banerjee, Associate Professor in Clinical Data Science and Honorary Consultant Cardiologist, Institute of Health Informatics, UCL, said:
“There is no question that the estimates of 2% of the population in England infected with SARS-CoV2 and over 60 000 daily cases are alarming figures because they signal that the pressure on hospitals and the NHS is still yet to peak. The strengths of the COVID-19 Infection Survey are that it is based on COVID-19 test-positive cases, and that it can detect changes over time. It may detect changes before other measures, such as hospital admissions, or mortality. However, there are some weaknesses and there is some uncertainty around these numbers. First, we do not know the accuracy of the PCR test and so it is difficult to estimate the true rate of COVID-19. Second, the true rate of infection is likely to be higher since not everybody with COVID-19 is getting tested. Third, although the survey is taken in a representative sample of the overall population, it may not be representative by region or different population subgroups, e.g. ethnicity or key workers.
“The increase in cases does tally with the period around Christmas and there is a definite trend of increasing infection rate and increasing daily cases since early December. People will be wondering why we did not lockdown earlier, given the data regarding the new strain but also given the experience and evidence from the last two lockdowns. We know that lockdowns work best and are shorter when they are early and stringent. While vaccination roll-out is crucial, we must also use this time to ensure that our Test and Trace infrastructure and delivery is far more robust, and that our borders are secure, so that we greatly reduce the risk of another peak in infections after this lockdown.”
Dr Julian Tang, Honorary Associate Professor/Clinical Virologist, University of Leicester, said:
“This upward trend of cases (and related hospitalisations and deaths) is likely to continue for another 2-3 weeks as the impact of social mixing during Christmas/New Year continues to be felt.
“But as the numbers of daily new cases start to fall towards the beginning of February, if we start to relax the restrictions then, this will give the virus a chance to surge again.
“So ideally we need to stay in lockdown beyond this, if we really want to suppress this virus sufficiently to allow the vaccination to reach the vulnerable and to avoid overwhelming the NHS.
“Understandably, this is a terrible time for businesses, but ideally, and purely from a virological viewpoint, if we can stick to the lockdown until 40-50% (for an R0=1.6-2.0) of the population have been vaccinated – which should include all the clinically vulnerable, their carers and frontline medical, teachers, delivery, postal, public transport staff and first-responders – then a relaxation of the restrictions may be safer and more sustainable.
“Of course, not everyone who is vaccinated will be fully protected after just one dose of vaccine – so we may need to vaccinate ~60% of the population with at least one dose of vaccine to achieve a true 40% level of population immunity (based on a true real-life overall vaccine effectiveness of 60-70%).
“So the timing of lockdown relaxations, from a purely virological viewpoint, will depend a lot on the vaccination rates and the real-life vaccine effectiveness.
“This also depends on the virus not mutating further to a more transmissible (with a much higher R0 requiring wider vaccine coverage) and/or a more severe form that will increase hospitalisation and death rates – either of which may prolong the lockdown to manage these new possible variants.
“So we really need everyone to stick to the lockdown restrictions, to reduce the spread of the virus, whilst these vaccinations are ongoing, and avoid overwhelming the NHS services.”
Prof Kevin McConway, Emeritus Professor of Applied Statistics, The Open University, said:
“These newly published numbers on the numbers of infections in the English community are alarming, though not surprising given the bad news we’ve all heard recently about rising rates of infection. The data come from the ONS Infection Survey, in which a reasonably representative sample of the English community population are tested for the virus, not because they have symptoms or are in a certain job or live in a place where mass testing is being done, but simply to monitor how infection levels are changing. Most of the information on the rapid rise in infection rates that we’ve seen in recent days comes from counts of confirmed cases, and those numbers can depend on which people are coming forward for testing. The pattern of who is being tested generally could well have changed over the Christmas period, when most aspects of life aren’t the same as usual. So it’s particularly important to check the changes in confirmed cases against survey results which, I’d expect, would be much less affected by changes in people’s behaviour in deciding to be tested.
“The ONS survey numbers, like the counts of confirmed cases, do show a rapid increase since the November lockdown ended at the start of December. The percentage of people who would test positive for the virus more than doubled in the four weeks between the week ending 5 December and the week ending 2 January. Very roughly speaking, the percentage was increasing, over that period, at a rate that corresponds to a doubling in infections every three weeks, ending up with an estimate that 1 in 50 people in the English community population were infected by 2 January. That number comes from a survey, and all survey data are subject to some statistical uncertainty, but it is a large survey, and ONS state that the interval representing the uncertainty is pretty narrow – from 1 in 45 to 1 in 50 (rounded to the nearest 5).
“Over about the same period, the number of daily confirmed cases in England rose even faster, ending up at the end of December at three and a half times the number at the beginning of the month. Now it’s not really meaningful to compare these two rates of increase, because the daily confirmed cases figure is essentially a count of new cases, while the numbers from the infection survey are for people who have an infection at the time they were tested, which will include some people who have just newly been infected together with others whose infection happened some days or even a couple of weeks earlier. Because of this difference, I’d expect the number of people who would test positive to increase more slowly than the number of new confirmed cases, as indeed seems to be happening – but I think the ONS data might be compatible with a slightly lower rate of increase in the pandemic than the new confirmed cases. There isn’t really enough data to be at all sure of that, though – and in any case, an increase this fast is alarming even if it does turn out to be slightly slower than the increase in confirmed cases might indicate. Some hospitals in certain parts of the country are already pretty full. The lockdown announced yesterday will reduce new infections, and vaccination might possibly start to reduce new infections. But those effects won’t show up in hospital admissions for another two or three weeks, because it generally takes time after they are infected for people to become ill enough to need hospital treatment. People going into hospital now could well have been infected two or three weeks ago, when the proportion of people infected was more like 1 in 80 than the current 1 in 50. The numbers needing hospital treatment are going to keep rising. If they do double in the next three weeks, as more people who are already infected need hospitalisation, things are going to get very difficult in hospitals across a lot of the country.
“The ONS data are less precise on the infection rates in different regions of England, because the number of people tested in each region is smaller than for the whole country. Given the inevitable statistical uncertainty, there’s really no clear evidence of a difference in infection rates between regions, except for two. The rate of positive tests in London is estimated at about 1 in 30, and London is a big region so that there isn’t much statistical uncertainty (from about 1 in 25 to 1 in 35). That is very high indeed. There are some weak indications that the rate in London may have levelled off in recent days, but that conclusion is very far from being statistically convincing – I can do no more than hope it’s true. The only region where the rate is lower is the South West, where around 1 person in every 135 would test positive (but with more uncertainty than in London – a range from 1 in 105 to 1 in 180). But you’ve got to remember that 1 in 135 is quite a high rate by the standards of just a couple of months ago. Indeed the rate in London was about 1 in 135 just about a month ago, at a time when the rate in the South West was only about 1 in 235. Infections have been increasing pretty fast in the South West, and there’s no place for complacency there or anywhere else.
“The new data also give information on the prevalence of the new variant of the virus, though there’s quite a lot of statistical uncertainty about many of those figures. The good news is that there’s some evidence that the prevalence of the new variant is levelling off in some of the regions where it has been dominant (London and the South East, but not really in the East). But that evidence is statistically pretty weak. The bad news is that the prevalence of the new variant is increasing everywhere else, may already have outstripped the older variants in the East Midlands, and isn’t far behind the older variants in some other regions.”
Dr Jonathan Pearson-Stuttard, Imperial Wellcome Trust Research Fellow, Imperial College London, and Head of Health Analytics at Lane, Clark & Peacock LLP (an actuarial and data analytics partnership), said:
“The ONS Covid-19 infection survey data provides the most robust estimates of virus prevalence in the community because it takes a random sample of the population, irrespective of whether an individual has Covid-19 symptoms. The ONS data therefore has consistently estimated higher prevalence than would be suggested by the daily PHE data. This data is very concerning given both the high number of people currently with Covid-19 and the pace of the increase in prevalence. This large increase will lead to a further increase in hospitalisations and sadly deaths from Covid-19 in coming weeks and add further pressures to the NHS that is already seeing record levels of Covid-19 patients in hospital. Not only is this of grave concern for the patients with Covid-19, but also the indirect impacts on healthcare services such as cancer surgery which will is likely to the morbidity and mortality of non-Covid patients too.
“We have developed a LCP Covid-19 tracker that combines the ONS Covid-19 survey data with the PHE daily testing data along with traditional actuarial techniques to provide estimates of daily Covid-19 cases for England and at local authority level. The LCP Covid-19 tracker estimates 1.2million had Covid-19 on the 27th December increasing further by 2nd January, a little higher than the ONS estimates but with very similar trends. Our estimates suggest that we have had 6 consecutive days of more than 80,000 new daily cases from 28th December to 2nd January. The Covid-19 tracker is at https://covid.lcp.uk.com.”
Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:
“The number of people currently with a COVID-19 infection is estimated by the ONS to be around 1 in 50, which is frighteningly high. For comparison, the ONS data shows that in June the numbers were around 1 in 4000. If we also highlight the huge numbers of confirmed daily cases, the fact that there’s more people in hospital now with COVID-19 than at any state of the pandemic, and that almost any graph you look at is on a steep upward trajectory, then the UK is clearly not in a good place right now.
“There is an optimistic future, with the rollout of the vaccine programme. The issue is that before we get to the point when we can all relax a little bit, there will be some grim times ahead for example with the inevitability that the UK will pass 100k COVID-19 deaths in the relatively near future.”
Prof Lawrence Young, Professor of Molecular Oncology, Warwick Medical School, said:
“As we face the biggest rise in the daily number of reported coronavirus cases, the Prime Minister has highlighted the progress being made in relation to the number of vaccinations and how these are being rolled out across GP practices and hospitals as well as the mass vaccination centres that will come on stream next week. The CMO presented data confirming the alarming increase in infections over the last few weeks and how the latest ONS data shows that 1 in 50 people are now infected. The new virus variant is fuelling this increase in the rate of infections across the whole country. This emphasises the need for national lockdown and for increasing the effort to roll out vaccination to vulnerable groups and healthcare workers as soon as possible as this will save the most lives in the shortest time. The PM stated that we are dealing with the virus ‘day by day and jab by jab’ but did not discuss the need for the second dose of the vaccine to provide the greatest level of protection for the longest time. There was no mention of how we can use this new period of lockdown to improve surveillance through testing, tracing and isolating or how such rapid testing can best be deployed to support students returning to schools and universities. We need to use this lockdown to stamp out the virus not only by vaccination but by breaking the chains of transmission (hands, face, space) and by using our testing capacity in a more determined and directed way.”
daily case number data:
https://coronavirus.data.gov.uk/details/cases
ONS data:
https://www.ons.gov.uk/news/statementsandletters/coronaviruscovid19infectionsurveyadhocrelease
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
Dr Amitava Banerjee: “I have no conflicts of interest.”
Prof Kevin McConway: “I am a Trustee of the SMC and a member of the Advisory Committee, but my quote above is in my capacity as a professional statistician.”
None others received.