On the subject of incoming flights we know from Taiwan that airports and planes are significant points of transmission.
So why did the UK government not suspend travel into the UK?
“Based on these factors and our experience, Chen is correct in asserting that this coronavirus can be found in the cabins of many airplanes, and therefore people should avoid flying. However, not enough emphasis is being placed on the roles of international airports in spreading COVID-19, due to the numerous passengers and many aircraft arriving for maintenance.From a statistical point of view, the probability of physically encountering the novel coronavirus or of being exposed to infected individuals in large international airports or in the cabins of airplanes is much higher than in homes, workplaces, schools or other public spaces.”
There is also this from the abstract of a study. It is a pre-print, the study is yet to be peer reviewed.
“Conclusion: International travel was directly associated with the mortality slope and thus potentially the spread of COVID-19. Stopping international travel, particularly from affected areas, may be the most effective strategy to control COVID outbreak and prevent related deaths.”
It isn’t as if there were no warnings about the dangers of transmission posed by travellers.
24 January: The WHO advises screening, interviews and contact tracing in “affected areas” – by this time most of Europe.
27 January: updated WHO guidance stresses the importance of screening international travellers.
11 February: The WHO emphasises again that ‘containment’ requires checking airport staff and strict quarantine measures.
26 February: Health Secretary Matt Hancock promises ‘extended measures’ at airports. They never materialise.
29 February: The WHO specifically criticises the lack of airport checks to contain COVID-19.
Professor Van-Tam rightly pointed out that, in the early weeks of February when the virus was seemingly confined to China, passengers from Hubei were quarantined on arrival in the UK. But, as the health tsunami spread and swept inexorably towards Britain, no action was taken to stem the flow of travellers from other badly infected countries or to check if they had symptoms.
Incredibly, as the global crisis worsened, Britain went it alone – as far as I can tell –among the nations of the world by keeping its borders completely open and imposing almost no compulsory (or even random) health checks on passengers arriving in the country.”