Market closure the key?

Is the closure of Shanghai's wet animal markets to thank for the precipitous drop in H7N9 cases from Shanghai from around mid-April? 

Back in 13.04.13 I mentioned we still had a few days to see if there was any impact based on the diagnostic testing lag of 10-12 days. Dr Kelso of the WHO influenza-A team thinks the drop and the market closures could be linked.