The Facts COVID-19 is the disease associated with the 2019 novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The pandemic related to this virus has transformed life for billions of people across the globe. Using population based data from England, we recently showed a strong independent relation over time between our calculated R value for COVID-19 transmission and the number of cases identified as definitely positive in the population. We determined that 26.8% of the population of the United Kingdom (UK) possibly had been infected by late April 2020 approximating to 18.2 million people. Reflection Different modelling approaches give different answers to the question of how many people in the UK and elsewhere have actually been infected by COVID-19, which all would agree in epidemiological terms is behaving very differently from other Coronaviruses that we have seen in the past. We are learning more and more about this virus. National policy is changing rapidly and COIVD-19 antibody testing is increasingly being applied. This will facilitate better datasets from population based studies. The picture will become clearer as more data accrues over time.

Background The COVID-19 pandemic has led to radical political control of social behaviour. The purpose of this paper is to explore data trends from the pandemic regarding infection rates/policy impact, and draw learning points for informing the unlocking process. Methods The daily published cases in England in each of 149 Upper Tier Local Authority (UTLA) areas were converted to Average Daily Infection Rate(ADIR), an R-value - the number of further people infected by one infected person during their infectious phase with Rate of Change of Infection Rate(RCIR) also calculated. Stepwise regression was carried out to see what local factors could be linked to differences in local infection rates. Results By the 19th April 2020 the infection R has fallen from 2.8 on 23rd March before the lockdown and has stabilised at about 0.8 sufficient for suppression. However there remain significant variations between England regions. Regression analysis across UTLAs found that the only factor relating to reduction in ADIR was the historic number of confirmed number infection/000 population, There is however wide variation between Upper Tier Local Authorities (UTLA) areas. Extrapolation of these results showed that unreported community infection may be >200 times higher than reported cases, providing evidence that by the end of the second week in April, 29% of the population may already have had the disease and so have increased immunity. Conclusion Analysis of current case data using infectious ratio has provided novel insight into the current national state and can be used to make better-informed decisions about future management of restricted social behaviour and movement.