Real-time Nowcasting and Forecasting of COVID-19 Dynamics in England: the first wave?

Abstract

England has been heavily affected by the SARS-CoV-2 pandemic, with severe 'lock-down' mitigation measures now gradually being lifted. The real-time pandemic monitoring presented here has contributed to the evidence informing this pandemic management. Estimates on the 10th May showed lock-down had reduced transmission by 75%, the reproduction number falling from 2.6 to 0.61. This regionally-varying impact was largest in London of 81% (95% CrI: 77%-84%). Reproduction numbers have since slowly increased, and on 19th June the probability that the epidemic is growing was greater than 50% in two regions, South West and London. An estimated 8% of the population had been infected, with a higher proportion in London (17%). The infection-to-fatality ratio is 1.1% (0.9%-1.4%) overall but 17% (14%-22%) among the over-75s. This ongoing work will be key to quantifying any widespread resurgence should accrued immunity and effective contact tracing be insufficient to preclude a second wave.

Combined epidemiological and genomic analysis of nosocomial SARS-CoV-2 transmission identifies community social distancing as the dominant intervention reducing outbreaks

“…Figure 1 presents the predicted period of peak HCW infectectiousness based on a combination of ± 2 days from date of symptom onset (n=30) or seroconversion data where symptoms were not present (n=13). The rapid rise in HCW infection is predicted to have been between March 16th and 25th overlapping with similar rapid rises in community cases reported elsewhere (3), and both symptom reporting by our community-onset cases and incidence of nosocomial cases.…”

“…Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Wuhan, China in December 2019 (1), since when over 40 million infections and 1 million deaths have been reported worldwide (2). New cases in the UK peaked during the first wave after implementation of progressive community social distancing (CSD) (3), starting with an announcement on March 16th that, with few exceptions, the whole UK population must stay at home, later being made mandatory on March 23rd. COVID-19 hospital admission then peaked around 8 days later (4).…”

How vaccination and contact isolation might interact to suppress transmission of Covid-19: a DCM study

“…The final panel provides estimates of infection fatality ratios (IFR) based upon the cumulative deaths and estimated infections or symptomatic cases (i.e., a clinical COVID-19 case). These ratios (0.18% and 0.32%) are substantially less than usually reported (Birrell, Blake et al 2020, Russell, Hellewell et al 2020, Streeck, Schulte et al 2020, Verity, Okell et al 2020), which may speak to an underestimation of prevalence based on serology or PCR testing. However, they are quantitatively consistent with surveys of ‘sentinel’ populations; for example, “In Manaus, the IFRs were 0.17% and 0.28%, considering PCR confirmed COVID19 deaths and probable COVID-19 deaths based on syndromic identification.” (Buss, Prete et al 2020).…”

“…One can regard the seronegative state as an enduring state of immunity that does not entail seroconversion due to infection: i.e., an immune state due to pre-existing immunity (Le Bert, Tan et al 2020, Ng, Faulkner et al 2020), mediated by T-cells (Grifoni, Weiskopf et al 2020, Le Bert, Tan et al 2020, Seo, Giles et al 2020) or vaccination (Fontanet and Cauchemez 2020, Houlihan, Vora et al 2020, Saad-Roy, Wagner et al 2020). This construction allows for the loss of detectable IgG antibodies (seropositivity) over months, while modelling a slower loss of protective (seronegative) immunity over years.…”

Time use and social mixing during and around festive periods: Potential changes in the age distribution of COVID-19 cases from increased intergenerational interactions

“…During the initial national lockdown, residents in England reduced the number of contacts and time spent on activities with higher risk of infection by 48%-74% as compared to what was observed historically (Del Fava et al 2020; Jonathan Gershuny et al 2020; Jarvis et al 2020). Consequently, the lockdown was successful in reducing the estimated effective reprodcution number ( R eff ) in England by 75% from 2.6 to 0.61 (Birrell et al 2020). The effects of the second national lockdown and subsequent regional restrictions are not yet known; however, temporarily lifting some of the restrictions in late December 2020 has been discussed given the “desire to socialise over Christmas” (Williams et al 2020).…”