Estimating the effectiveness of routine asymptomatic PCR testing at different frequencies for the detection of SARS-CoV-2 infections oleh Joel Hellewell, Timothy W. Russell, The SAFER Investigators and Field Study Team, The Crick COVID-19 Consortium, CMMID COVID-19 working group, Rupert Beale, Gavin Kelly, Catherine Houlihan, Eleni Nastouli, Adam J. Kucharski