In this part, I will talk about national and international-level measures to control and mitigate epidemics. The objectives of this part are: to define entry screening; to define exit screening; and to discuss the potential benefits and limitations of travel restrictions and entry screening for pandemic influenza. When infectious diseases emerge or re-emerge, considerable efforts may be made to contain the new pathogen geographically, and stop it from traveling across national or international borders. For example, during the SARS epidemic in 2003, the World Health Organization advised people not to travel to affected areas including Hong Kong, Toronto, Beijing, and some other areas. Some countries established entry screening, for example in Hong Kong all arriving travelers were required to complete a health declaration form, and have their body temperature checked. This is known as entry screening. For busy airports such as the one in Hong Kong, millions of passengers arrive every month, and so entry screening can be labour-intensive and very costly. In Singapore, 400,000 passengers were screened in a few months in 2003, and while no SARS cases were identified, it was suggested that the expense was justified in light of the major political, social and economic impact if even a single case arrived in the country. Later in the SARS epidemic, in Hong Kong health declaration forms were also required for outbound passengers, as a form of exit screening. In the years following 2003, a series of simulation studies considered the potential application of travel restrictions and border screening in controlling the next influenza pandemic. Those studies consistently found that travel restrictions would need to be extreme, with more than a 99% drop in travelers, in order to delay importation of pandemic influenza for just a few weeks. Meanwhile, the economic costs of travel restrictions could be considerable. One motivation for travel restrictions and entry screening would be to buy time while a vaccine is being developed and produced. However, Cooper and colleagues suggested that even very intensive measures could only delay epidemic spread for a few weeks, and that resources might be better directed to local control measures. Entry screening was unlikely to be useful because many persons infected with influenza have no symptoms or only very mild symptoms, and some travelers may be incubating disease, that is infected but not yet symptomatic, at the time they pass across national borders. Nevertheless, when swine flu emerged in North America in 2009, many countries implemented some form of entry screening, as much for political considerations as for public health. In China, Mexican travelers were rounded up and quarantined, while some countries cancelled direct flights from Mexico. We assessed the measures implemented by 35 selected locations and identified four broad approaches to entry screening used alone or in combination with other measures. First, temperature checks were performed onboard aircraft prior to disembarkation. Second, health declaration forms were collected from every traveller or all travellers from countries identified with confirmed H1N1 cases. Third, arriving travellers were observed by alert staff for influenza symptoms such as cough. Fourth, travellers were scanned for elevated body temperature by thermal scanners. Based on the idea that entry screening should delay the onset of local transmission, we determined the dates of the first confirmed imported cases, and the dates of the first local case – that is a case not epidemiologically linked with imported cases – and compared these dates for various locations. We found that locations which implemented some form of entry screening did tend to have longer delays, but only by around 1-2 weeks. The uncertainty bound of the delay estimates ranged from no delay up to 20-30 days delay. In general, a delay of 1-2 weeks might be useful if the additional time permitted more comprehensive planning and preparation for a local epidemic, or shortened the time required for other pandemic mitigation measures such as school closures to be sustained. However any benefits of local screening should be balanced against the considerable resources required to implement screening.