So, the evolved corona virus has an expected incubation period of somewhat more than the flight time from A to B, by a week to two weeks. Screening will only detect that part of the population that is sick enough to be detectable, and not sick enough to have been incapacitated to the extent that boarding the flight would have been denied or not possible due to health of the patient.
Without immunisation, there is only one method to stop a spread of an aerosolised type virus, or one that is otherwise transmitted from contact, and that is to restrict contact for the period necessary to ensure symptoms can be identified.
FWIW, Elvis has already left the building, the screening is lipgloss, and is limited in efficacy. The preliminary R nought on this one is high enough to need prompt and substantial controls in order to stop spread in the population, being higher than the SARS or MERS rates, but this is early days. Movement interactions over the last few weeks will become key in attempting to put the genie back in the bottle, but screening itself is currently is not the panacea of defence.
The period of incubation to the point of being contagious will be a major factor in developing the strategy to limit the spread. So far the lethality of the latest outbreak is lower at present than MERS or SARS have been, but is still serious.
Masks and gloves, hand-washes, and minimising contact with others. go to cdc.gov for latest info.