Vaccination

What if the H7N9 vaccination wasn't just a preventative measure against swine flu?

It seemed like the flu came out of nowhere and yet, in no time at all the government manufactured a vaccination. Were lab workers diligent, or could the virus itself have been man-made?

Chase McKinney works as a dispatcher at 9-1-1. Taking emergency calls, it becomes immediately obvious that the entire city is infected with the walking dead. His first goal is to reach and save his two children.

Could the walls built by the U.S.A. to keep out illegal aliens, and the fact the Mexican government could not afford to vaccinate their citizens against the flu, make the southern border the only plausible destination for safety?