Originally Posted by
Time Traveller
... yet another clumsy and unpredictable quarantine by the UK government, instead of more logical arrival test and tracing.
Incubation is up to 7 days before symptoms, infectious 1-2 days before that. PCR swab test has very high false negative rate if used too early, even testing at 8 days after exposure has 20% false negative rate. For one week trips (mean exposure time around 4 days before arrival in uk) you will miss well over half of holiday-acquired cases, even if you test everyone. A one week quarantine (if -ve) with test at one week will catch maybe over 80%, and
may be a logical compromise, but test-on-arrival is far less logical than quarantine.
See e.g.
https://www.itnonline.com/content/co...used-too-early for the testing science.