The recent report of a businesman who traveled to China and came back with a severe case of H7N9 has implications for the probability of a pandemic. The population of Taiwan is only about 23 million. I don’t know how many people from Taiwan traveled to China last month, but lets say it was 200,000. Of these, at least one developed a life-threatening infection. The population of the area in China with reported infections is at least 200,000,000. If we apply a 1 in 200,000 incidence to this group we would expect 1,000 severe infections, an order of magnitude higher than those reported. Given the Chinese government’s past history of covering up SARS and H5N1 cases, a underreport by a 1,000 cases is all too possible.
The reported cases of 100+ are already straining the boundaries of what can be explained without assuming a pandemic has begun. A 1,000 cases would go right past that barrier. And I think there is a good chance that is exactly what has happened.