Lot of discussion of airport testing vs quarantine in UK. Think it's useful to separate into two related questions: 1) Could testing help reduce quarantine requirements? (Yes, if feasible.) 2) Would single test at arrival detect majority of incoming infections? (Probably not.) 1/
It's well known that screening for symptoms at arrival can miss infections, because people may be too early in their infection to detect, especially if epidemic growing in origin country (because people more likely to have been infected recently). E.g. elifesciences.org/articles/05564 2/
Similarly, people tested early in their infection may get negative result, and even people tested while symptomatic may not always have positive result (e.g. eurosurveillance.org/content/10.280… & academic.oup.com/cid/advance-ar…) 3/
Work by my colleagues @samclifford @BQuilty and others estimated that repeat testing & short period of quarantine could give similar reduction in risk as longer quarantine without test medrxiv.org/content/10.110… 4/ 
Also worth considering international examples, e.g. French Polynesia, which requires negative test pre-arrival and self-test four days after arrival (tahititourisme.com/en-us/covid-19/), but has seen local outbreaks after reopening to travellers in mid-July (rnz.co.nz/international/…) 5/
Need to look at ways to reduce quarantine burden (both for travellers and domestic contacts of cases), but also need to consider the relative benefits/logistics of the available options. 6/6
