Quantifying the impact of physical distance measures on the transmission of COVID-19 in the UK

Christopher I Jarvis; Kevin Van Zandvoort; Amy Gimma; Kiesha Prem; Petra Klepac; G James Rubin; W John Edmunds

We assumed that contact patterns prior to physical distancing were similar to those observed in the POLYMOD data, and that the duration of infectiousness and the probability that a single contact leads to transmission did not change during the study period. Under these assumptions, the relative reduction in R0 is equivalent to the reduction in the dominant eigenvalue of the contact matrices. By multiplying the value of R0 prior to the interventions by the ratio of the dominant eigenvalues from the POLYMOD and CoMix contact matrices, we were able to calculate R0 under the physical distancing interventions. Prior to interventions we assumed R0 followed a normal distribution with mean 2.6 and standard deviation of 0.54 based on a metaanalysis of the literature presented in the supplementary material.