The discussion about China's official #Covid_19 statistics is important, for political and epidemiological reasons. What can be said about it? @dhnexon @namalhotra @OttoKolbl @DrEricDing @yindavid @chenchenzh @XihongLin @cjw_phd @yangxifan @Dali_Yang Please add/correct/refine
It is crucial to combine all available information and data points on this issue, as claims about responsibility for spreading #Covid19 are moving into a higher gear every day: UK businessinsider.com/coronavirus-bo… France: europe1.fr/international/…
Beyond the international "blame game" heating up, epidemiologists, virologists and health studies researchers need proper data and/or plausible estimates on many aspects of the pandemic. Since China is weeks ahead of the curve, its data are critical to understand #Covid_19 better
What are official Chinese statistics likely getting wrong? a) number of deaths (especially in Wuhan). #Covid_19 deaths PLUS other fatalities due to lockdown and 4 weeks collapse of healthcare system in Wuhan could be anywhere between 3k and 40k rfa.org/english/news/c…
#Covid19 deaths in certain groups of infected persons were likely underreported in official numbers: 1) prisoners (exception in Shandong?). 2) infected persons in Xinjiang province. 3) military personal. So, an estimation of the potential range for whole China could be 3.3k-40k?
As no hospitals collapsed outside Hubei, most deaths are concentrated there. It's difficult to ascertain how many deaths in Wuhan were directly caused by the new #coronavirus and how many were "collateral damage". Hence, Covid-19 fatality is probably closer to lower band.
b) Overall number of #Covid_19 infected persons (today 82,424) is too low. Real number might be 1,5-3 times bigger. Main reason for this: at the beginning tests were not enough/contact tracing only got ramped up by end of January. Many early phase cases have remained undetected
Some modelling suggests that perhaps 430,000 people got infected and more than 19,000 died telegraph.co.uk/news/2020/03/2… Yet this kind of simulations uses a set of "informed" assumptions that are not validated by empirical observations.
Interestingly, the current naive case fatality rate for Wuhan is not much different from results of this simulation. In the above study it's 4,41%. According to the Wuhan raw data it is now 5,1% docs.google.com/spreadsheets/d…
SCMP reports instead that internal Chinese documents show "more than 43,000 people in China had tested positive for Covid-19 by the end of February but had no immediate symptoms" scmp.com/news/china/soc… These are not included into the official numbers.
43,000 seems a realistic number. What happened to these "excess" cases? Most simply healed. Some got symptomatic. Few died not to be included by official statistics. After Wuhan's lockdown Jan 23 and with the testing/isolation system in place, undetected cases went down fast.
c) China's official numbers of Covid-19 infections do not include asymptomatic cases. This is a well known fact. However, all cases are put under quarantine and once asymptomcatic cases become symptomatic, they'll be included into the statistic caixinglobal.com/2020-03-23/des…
The way Covid-19 infections are categorized and counted was changed several times for statistical, epidemiological and administrative reasons taiwannews.com.tw/en/news/3883982 and voanews.com/science-health… It's not simply a story of hiding. The history of this odd process needs to be written
The problem of "asymptomatic and mild cases" remains complicated and requires more research. Chinese officials/#WHO at some point stated that asymptomatic cases are between 1 and 3%. In Korea around 20% of Covid-19 patients have no shown symptoms
scmp.com/news/china/soc…
scmp.com/news/china/soc…
How big is the share of asymptomatic cases really? Perhaps between up to 1/5 as data from Heilongjiang province suggest caixinglobal.com/2020-03-01/chi… see also: taiwannews.com.tw/en/news/3883982 But we don't know for sure yet.
Estimates from other studies (cruiship case in Japan, Japanese citizens evacuated from Wuhan) indicate that the share of asymptomatic cases (at the time of testing) is between 18% to 30% of all cases eurosurveillance.org/content/10.280…
Other reports indicate that 1/3 of Chinese cases were (initially) asymptomatic bloomberg.com/news/articles/… Excluding asymptomatic cases from official numbers complicates epidemiolgical studies. Virological studies on transmission paths and clinical studies would also need these data
Diplomatic "encouragement" should make the Chinese Center for Disease Control and Prevention to include all Covid-19 cases in the official statistic, or at least fully share their internal numbers about "asymptomatic cases" with the international scientific community
Finally, it is important to note that new infections in China do not continue to go "under the radar" scmp.com/news/china/sci… as a SCMP headline claims. Due to mass testing, a contact tracing system and rigorous isolation measures, every single case will likely get detected.
Wu Zunyou, a researcher with the Chinese Center for Disease Control and Prevention, says that “asymptomatic people won’t cause the infection to spread because in China all close contacts are quarantined in isolated units” bloomberg.com/news/articles/…
Is it possible that China's current anti-covid-19 measures could fail eventually? Yes, for various reasons. The rapid response system put in place after SARS malfunctioned. Due to tampering, it did not operate adequately to suppress this new virus early on nytimes.com/2020/03/29/wor…
So, why trust China's containment approach for now? i) given the high R of Covid-19, the CCP can't simply hide another large-scale outbreak. The CCP is in fact afraid of a second wave of infections. ii) Known protocols how police handles all new cases-test/contact tracing/isolate
iii) China's system for contact tracing. Authorities use extended surveillence powers: digital and physical health control measures. This is an authoritarian overreach. But key elements are similar to #Singapore and #Southkorea--countries which credibly manage to contain Cov19
iv) China's massive health security measures, improved protocols for suspected cases (multiple times) and world class protective equipment for medical professionals and strict seperation of Covid-19 and other patients, which prevent a spread in hospitals.
As @chenchenzh points out, we should expext that individual cases & small clusters will continue to emerge in Mainland China,
as is the case in TW, Singapore and HK.
as is the case in TW, Singapore and HK.
It needs to be noted that Italy among other countries also does not include "asymptomatic cases" in its official Covid-19 statistic telegraph.co.uk/news/2020/03/2… and the #WTO does not consider "asymptomatic transmission a significant factor in the outbreak" nytimes.com/2020/02/27/wor…
Importantly, the debate about the CFR should not distract us from the fact that modelers and epidemiologists have already ALL the crucial data on #Covid_19 in China to run their models on outbreaks and consequences in other countries. Here is a data set docs.google.com/spreadsheets/d…
Update: from 1 April on, Chinese official stats include asymptomatic cases. Isolation procedures for all persons infected with Covid-19 and suspect cases will be stricter. Asymptomatic cases will be 14 days in special hospital quarantine PLUS 14 days in public quarantine facility
