According to a story in the Washington Post, the US plans to triple airport quarantine stations in hopes of keeping infectious diseases out of the country.
The plan is a response to rising fears about bioterrorism or a potential pandemic of respiratory illness. For example, experts fear that a highly lethal form of influenza now circulating among birds in Asia, if it undergoes certain genetic changes, could start spreading rapidly among humans, potentially killing millions. In an age of global air travel, such an illness could jump from foreign countries to the United States in hours.
This makes sense, but imagine a scenario in which thousands are trying to get out of east Asia into North America to escape a pandemic, only to find flights have been cancelled. An alternative tactic would be to fly to whatever country still accepts flights from Asia, and then to make their way to North America by whatever means possible. It could mean a bonanza for snakeheads, the human smugglers who now bring illegal immigrants into Canada and the US from Asia.