Covid-19 and social distancing, the effectiveness of the Wuhan model
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Interpersonal safety distances, as seen, represent the key to reducing the risks of Covid-19 transmission. And the 'Wuhan model' - that is, the strict measures of social distancing (social distance) applied in the great Chinese metropolis where the new coronavirus first manifested itself - it is unique in terms of effectiveness. As confirmed by the epidemiological data and the scientific studies set out below.
SARS-CoV-2. The first outbreak, from dawn to dusk
the 31.12.19 the Municipal Health Commission of Wuhan (China) reported al China Country Office by WHO (World Health Organization) 44 cases of pneumonia of unknown etiology in the capital of the Province of Hubei. (1)
the 7.1.20 the CDC (Center for Disease Control and Prevention) of the People's Republic of China told WHO the identification of the cause of pneumonia in a novel coronavirus (2019-nCoV).
the 9.1.20 Chinese authorities have made public the genomic sequence of the virus. In the days immediately following, news of positive cases for laboratory tests were received in Thailand, Japan, South Korea. As well as in other provinces of China. (1)
the 30.1.20 WHO has declared an international public health emergency (Public Health Emergency of International Concern). On 11.2.20 he gave the virus the name Covid-19. On 11.3.20 he declared the pandemic.
the 18.3.20 Chinese authorities have declared the absence of new cases of contagion in Wuhan. (2)
Wuhan. The miracle of a model
'Contain infections respiratory is particularly difficult when they are characterized by asymptomatic transmission or with mild symptoms, that is, before the onset of the disease. ' (3)
On 23.3.20 the magazine Science has published the study of an international group of researchers from the Universities of Oxford, Harvard, Boston, Southampton, London, Paris, Turin, Beijing. (3)
'The Chinese government has taken the most comprehensive, thorough and rigorous prevention and control measures as soon as possible, which have proven highly effective at this stage. ' (3)
Always on 25.3.20 The Lancet has published a research - elaborated by Center for the Mathematical Modeling of Infectious Diseases COVID-19 Working Group - which in turn examines the Wuhan model and confirms its extraordinary effectiveness in protecting public health. (4)
The Great Wall against the virus
The Chinese government dealt with the outbreak by immediately erecting a great wall around its epicenter - a metropolis with 11 million inhabitants - which was literally bombarded with medical supplies and health personnel:
- the #StayAtHome order, #RestiamoaCasa, has drastically reduced every move. Identity checks at the entrance to residential buildings, closure of schools and workplaces, suspension of internal public transport and to / from the rest of the PRC (People's Republic of China),
- 154 medical teams with 1.700 operators, arriving from different provinces, they were already operating in the hospitals of the capital of Hubei. The level 1 state of emergency (maximum alert), on 29.1.20, in 31 provinces and 44 prefectures of the country. (4)
Mathematical models
Further studies waiting for peer-review (i.e. peer-reviewed, by experts in the same scientific field) evaluated the Wuhan model using mathematical models. With the aim of evaluating its effectiveness with respect to the alternatives (only hypothetical and abstract) of different approaches. (5, 6)
Researchers they calculated the different scenarios that could have been achieved if the Chinese government had decided on a progressive or non-intervention intervention. Considering the initial scenario, the metropolitan context and its demographic, the transmissibility of Covid-19 from person to person and by contact.
The mathematical models have in turn confirmed how non-pharmaceutical interventions based on prolonged social distancing have been able to significantly reduce the curve and the epidemic peak of COVID-19. With the result of easing the already acute pressure on the health system and saving thousands of lives.
The case of Singapore
The effectiveness of the interventions based on a drastic and prolonged social distancing - in the initial contrast to the spread of both the SARS and COVID-19 viruses - was then demonstrated in a study conducted in Singapore. (7) This study, published in The Lancet Infectious Diseases, it is also noteworthy in consideration of two aspects:
- population density extraordinary. 7.953 inhabitants / km2 in Singapore, compared to 205 inhabitants / km2 in Italy (World Bank. See note 8),
- success of Singapore in effectively mitigating the spread of both viruses in the community.
The complexity of the system adopted, in this study as in the previous ones on Wuhan, does not allow to evaluate the isolated impact of each of the individual containment measures. Nonetheless, the conclusions appear solid. The combination of quarantine, school and workplace closures was effective in a potentially high risk environment.
This system, according to the researchers, it allowed for an average number of infections in the measure of 99,3% compared to the hypothetical basic alternative scenario (no intervention). The transmission of symptomatic and asymptomatic cases was thus prevented, compressing the epidemic and removing the so-called peak.
Provisional conclusions
COVID-19 it is a serious respiratory disease still lacking effective therapies and vaccines. Its impact on health systems is exceptionally severe, as the current situation of the pandemic is demonstrating. The application of severe social control measures (social distancing and safety distances) seems to be the only strategy actually suitable for containing the spread of the disease.
It is also necessary set up an early detection, reporting and rapid reaction system to prevent the spread of new infectious diseases in the future. In fact, in the initial stages, the number of individuals who have contracted the virus can be dangerously underestimated due to asymptomatic transmissions, insufficient sensitization and delays in diagnosis. (9)
The strategy adopted by China, which proved capable of flattening the curve of rapid rise in cases of new infections, should be considered by the international community. Big data has played and will continue to play an important role in public health management. (6)
Systemic approach
The interventions more drastic and therefore effective non-pharmacologicals have an inevitably dramatic impact, in terms of income reduction and job losses, which require immediate liquidity support to defend productive capacities and economies otherwise forced into deep recessions. Where there is a lack of support from a superior economy (as is the case in China) or from international solidarity systems, enormous expansionary financial policies are indispensable to avoid the collapse of the company.
An example of a Causal Loop Diagram illustrates some of the components that interact in society in response to the threat of COVID-19. (See note 10)
A systemic approach it can help policymakers look beyond the chain of infection. To better understand the multiple implications of decisions and (in) actions, in the face of extremely complex situations that involve many interconnected factors. The causal circuit diagrams (Causal Loop Diagram, CLD, v. image) are useful tools to identify the causal connections between the various elements of a system and to predict how changes in one element overlap with changes in others and return to itself, through circuits of feedback which potentially affect the state of the entire system. (10)
Dario Dongo and Martina Novelli
Note
(1) WHO. Novel Coronavirus (2019-nCoV) - Situation Report 1, 21.1.20, https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200121-sitrep-1-2019-ncov.pdf?sfvrsn=20a99c10_4
(2) Huxia. China's Wuhan reports zero increase in novel coronavirus infections. Xinhua, 19.3.20/XNUMX/XNUMX, http://www.xinhuanet.com/english/2020-03/19/c_138894828.htm
(3) Moritz UG Kraemer, Chia-Hung Yang, et al. (2020). The effect of human mobility and control measures on the COVID-19 epidemic in China. doi: 10.1126 / science.abb4218
(4) Prem K, Liu Y, Russell TW, et al. (2020). The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modeling study. Lancet Public Health. https://doi.org/10.1016/S2468-2667(20)30073-6
(5) Guopeng Zhou, Chunhua Chi. A model simulation study on effects of intervention measures in Wuhan COVID-19 epidemic. MedRxiv (pre-publication pending peer-review), Feb. 2020 https://doi.org/10.1101/2020.02.14.20023168
(6) Yuan Zheming, Chen Yuan. A simple model to assess Wuhan lock-down effect and regional efforts during COVID-19 epidemic in China Mainland. MedRxiv, Mar 2020 (pre-publication pending peer-review), https://doi.org/10.1101/2020.02.29.20029561
(7) Koo JR, Cook AR, Park M, et al. Interventions to mitigate early spread of COVID-19 in Singapore: a modeling study. Lancet Infect Dis, 23.3.2020. https://doi.org/10.1016/S1473-3099(20)30162-6. Quoted in: Joseph A Lewnard, Nathan C Lo, Scientific and ethical basis for social distancing interventions against COVID-19. Lancet Infect Dis, 23.3.2020 https://doi.org/10.1016/S1473-3099(20)30190-0
(8) World Bank. Population density (people per sq. Km of land area), 2018. https://data.worldbank.org/indicator/en.pop.dnst
(9) Yan Niu Fujie Xu, Deciphering the power of isolation in controlling COVID-19 Outbreaks. The Lancet Mar 2020, https://doi.org/10.1016/S2214-109X(20)30085-1
(10) Bradley, Declan Terence et al. (2020). A systems approach to preventing and responding to COVID-19. EClinicalMedicine, Volume 0, Issue 0, 100325. https://doi.org/10.1016/j.eclinm.2020.100325
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
