Did the Swine Flu Escape from a Lab?

National Public Radio notes that Professor John Oxford at St. Bart's and the Royal London Hospital says that the 1957 H1N1 pandemic probably started when it escaped from a lab:

"We reckon now, in retrospect, it was probably released accidentally from a laboratory, probably in northern China or just across the border in Russia, because everyone was experimenting with those viruses at the time in the lab." It was nothing malicious, Oxford believes, just some flu vaccine research that broke out of containment.

Similarly, Bloomberg notes:

Some scientists have speculated that the 1977 Russian flu, the most recent global outbreak, began when a virus escaped from a laboratory.

In 2005, scientists thawed out samples of the 1918 flu and tested it. A new study says that the current swine flu is very similar to the 1918 flu, and that people who lived through the 1918 epidemic have immunity to the current flu.

Leading flu expert Adrian Gibbs believes the current swine flu may have escaped from a lab.

It is also interesting that 2 of the 3 flu pandemics of the last century - the 1918 Spanish Flu and the 1976 swine flu scare - both started at military bases. Specifically, the 1918 flu started at Fort Riley, Kansas. The 1976 swine flu started - and never spread beyond - Fort Dix, New Jersey. It is unclear whether or not those bases conducted defensive biowarfare research.