Where are we REALLY along those curves (Part 2 - China)

Understanding China’s experience in the pandemic is important because they were the first to confront the disease. I have heard concerns expressed that the data coming out of China may not be 100% reliable because of government controls on what gets reported, but regardless of the details, clearly there has been success at controlling disease spread. Reports last week (<—use google translate for this & several of the other links) indicated several days without local transmission in China, and that more cases were being imported than transmitted locally. The focus has turned to better understanding the role of asymptomatic infections in contributing to any further viral spread. Data coming out of the Chinese literature indicates “as of February 11, the Chinese Center for Disease Control and Prevention had received a total of 72314 domestic reported cases, including 889 cases of asymptomatic infection, accounting for about 1.2%.” This is lower than some other estimates I’ve seen, but certainly enough to seed new outbreaks. Other new work indicates that nearly 60% of cases in Wuhan were “unascertained” or not formally tested or included in the official numbers, and that non-pharmaceutical interventions, once implemented, were estimated to have prevented 95% of infections.

As with the 1918 influenza pandemic, data shows how these non-pharmaceutical interventions worked in China. This model shows how the curve WOULD have progressed as cases started to climb without further interventions:

Figure 4. Four-period susceptible-exposed-infectious-recovered modeling of the Covid-19 epidemics in Wuhan.

As the curve started to level off, further modeling shows that even as the curve starts to peak, non-phamaceutical measures must be maintained to start actually moving DOWN the curve. This model shows what would have been expected to happen if transmission had continued without further measures even as the curve started to level off:

Figure 4. Four-period susceptible-exposed-infectious-recovered modeling of the Covid-19 epidemics in Wuhan.

So…CLEARLY all these efforts we’re putting in at social distancing and other measures to limit spread do work, but must be maintained even after the numbers of new cases start to level off. As Hubei province starts opening up to the world again — outbound travel restrictions were lifted March 25th outside the city of Wuhan — the outstanding question for China and the rest of the world is how to maintain this success.