Covid-19
Philip Thomas was interviewed, together with Prof. Barry McCormick, by Andrew Neil on Times Radio Drive Time, 27th October 2020. Listen here
Philip Thomas was interviewed by Nick Ferrari on LBC radio, 15th April 2020. Download
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Thomas, P., 2020, "The length and severity of the coronavirus recession estimated from the dynamics of relaxing lockdown", Nanotechnology Perceptions, 16, 100–129. Download here
The J-value is used to cast light on the policy of lockdown and its relaxation by linking findings from epidemiological and economic analysis. A new, two-cohort model is applied to the coronavirus epidemic to allow for different sections of the population exhibiting different responses to the same disease. Optimal parameter sets are generated by adjusting the model to fit the data on new daily cases in England up to 10 April 2020. While several sets of parameter values give an equally good match to the data, a common feature is that the disease transients for the controlled second wave of the disease are long-drawn out, with tails resulting from an easing of restrictions in May 2020 lasting to the end of 2021 or later. A further feature in common is the lack of population or herd immunity at the end of the second wave, which leaves the population of England, and the UK by extension, open to further significant waves of the infection.
While considerable uncertainties remain with the epidemiology, there is no doubt that the positive feedback nature of the Covid-19 epidemic will make controlling the present outbreak a very difficult task, especially if the main regulating tool selected is the coordinated behaviour of 67 million people. The likely economic effect is analysed of the years-long process to move out of lockdown sufficiently slowly so as not to cause excessive strain on the health services. In the Extended Base Case, annual GDP will fall by 23.5% in 2020 and is not likely to recover to pre-lockdown levels until 2024. Applying the J-value derived Bristol Curve of population-average life-expectancy versus GDP suggests that the strategy of restriction followed by gradual relaxation is likely to result in a net cost, in terms of average human lives lost, that will be comparable with the UK's sacrifice over the six years of World War Two. A policy of lockdown followed by gradual relaxation is likely to do much more harm to the nation's health than good.
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Thomas, P., 2020, "J-value assessment of how best to combat Covid-19", Nanotechnology Perceptions, 16, 16–40. doi: 10.4024/N02TH20A.ntp.16.01 (or Download here)
The new coronavirus infection will continue to pose a very severe challenge to the UK and to all countries around the world for the next 12 to 18 months. An epidemic model has been developed to explore the range of possible actions open to the UK and other nations to combat the virus. A "business as usual" policy would lead to the epidemic being over by September 2020, but such an approach would lead to a loss of life in the UK little less than that it suffered in the Second World War. Using the J-value without constraint suggests that exceptionally high spending would be justified for the three strategies that could reduce significantly the numbers of cases and deaths compared with the unmitigated epidemic. However such high spending is likely to come up against the J-value GDP constraint, whereby the measure should not so decrease GDP per head that the national population loses more life as a result of the countermeasure than it gains. The challenge for the UK Government (and other governments around the world) will be to manage its interventions so that the recession that is now inevitable is not significantly worse than that following the 2007 – 2009 financial crash.
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Thomas, P., 2020, "The options for the UK leaving the coronavirus lockdown of 2020", Nanotechnology Perceptions, Vol. 16, 130–150 Download here
A computer simulation of the Covid-19 epidemic has been updated with data that became available on 14 May 2020. The model parameters have been adjusted (i) to provide the best match to data from Public Health England on daily new lab-confirmed infections to 30 April 2020 and (ii) to ensure that the model reproduces the Office of National Statistics central estimate of the average number of recently infected people in England in the week before and the week after 3 May 2020. The new information allows outline guidance to be given for the first time on the approximate consequences of each of the four main options for the UK coming out of lockdown in the absence of an effective vaccine. The options may be ranked based on minimising the sum of deaths due to Covid-19 and those due to national impoverishment. The Government's currently declared aim of keeping the basic reproduction number below 1.0 emerges as the worst in terms of life preservation.
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Thomas, P., 2020, "Measuring and Controlling the Covid-19 pandemic", Nanotechnology Perceptions, IN PRESS Download here
A system has been devised to measure the social distancing index (SDI)—also known as the basic reproduction number—on a daily basis, as well as the R-rate and the number of active infections. The predictor–corrector measurement tool, which incorporates both a single cohort and a two-cohort model of the Covid-19 epidemic, has been applied to England. The measurements have been corroborated against spot figures calculated from data for England from the Office of National Statistics Coronavirus Infection Survey Pilot. They give comparable accuracy and are available 10 days earlier. Accurate measurement has required the development of a correction factor to be applied to the Cases by Date Reported based on the number of tests carried out. Proper comparability is now possible for the first time between daily numbers of cases on different dates. It has been necessary, in addition, to account for the level of prior immunity in the population due to T-cells. Recent research showing that roughly 1 in 8 people carries such immunity is confirmed by the validation of the predictor– corrector model against ONS survey data on active infections. The measurement system has shown that England’s R-rate was either approaching or below 1.0 at the time the country entered its second lockdown on 5 November 2020. The action of the government in imposing the lockdown suggests it might not have been aware of this situation. The capability of the new measurement system to provide timely feedback to decision-makers allows them the freedom for the first time to control the SDI to a setpoint of their choice. Policymakers need no longer see their choices of Covid-19 strategies as binary: either lock down or let the virus rip. The predictor–corrector measurement system allows a third way, whereby the SDI is controlled to a series of setpoints chosen to minimize the overall harm to the nation’s health and economy. The point is illustrated with two scenarios that consider the effects of mass vaccination of the English population from December 2020 to the end of the epidemic in late 2021.
The R-rate is kept below 1.0 at all times in the first scenario, whereas in Scenario 2 the SDI is set initially at the value, 1.5, it had just before England went into the first set of Tiers on 17 October 2020. However, the R-rate quickly falls below 1.0 because of the immunity from various sources: from T-cells, from Covid-19 recovery and from vaccination. The total number of deaths is predicted to be similar under both scenarios, but the second allows somewhat greater economic freedom at the start.
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Thomas, P., 2021, "Vaccine-mediated exit strategies from England's Covid-19 lockdown", Nanotechnology Perceptions, submitted February 2021. Download here
An assessment is made of vaccine-mediated exit strategies from England's Covid-19 lockdown. Two linked methods are considered. The first, termed the gradualist approach, assumes that the R-rate is controlled to a value close to 1 and that the Social Distancing Index (SDI), which measures the nation's level of interpersonal contact, is allowed to increase continuously to the point where it can increase no further and society and the economy are fully open. The second method, termed the two-step strategy, adopts the gradualist approach initially, but then, after a certain time, the SDI is stepped to its maximum value, which implies the immediate removal of all restrictions.
It is found that, while vaccination-generated immunity makes a very valuable contribution to overall immunity, the other components, prior T-cell immunity and immunity generated by infection, are at least as important. Infection generated immunity needs to be the largest component if all restrictions are to be removed under both strategies. Exiting the lockdown to the point where all restrictions can be eased fully requires a narrow path to be followed during the spring and early summer of 2021, keeping the R-rate in a central band around 1.0. Close control of the R-rate is needed and this will require the R-rate to be measured accurately, continuously and rapidly. The gradualist approach might allow all restrictions to be lifted by the end of the summer, while the two step strategy might offer the prospect of full derestriction by the end of May 2021.