From Chain Reaction to Grid Reaction: Mobilities & Restrictions during SARS & Coronavirus

From Chain Reaction to Grid Reaction: Mobilities & Restrictions during SARS & Coronavirus

Historically, epidemics have been closely related to population mobility. The COVID-19 outbreak is special in that, population mobility in China in the year 2020 is not only unprecedentedly prevalent and frequent, but has also become a prerequisite for the economy and many people’s livelihoods.

The circulation of goods and the movement of people are arguably more important than assembly lines in factories in sustaining economic growth. The COVID-19 epidemic and the subsequent responses are particularly impactful because they abruptly halt what we may call a “mobility economy”.

The meaning of mobility has changed

This specific context can be discerned through a comparison to the severe acute respiratory syndrome (SARS) outbreak in 2003. Striving to contain the SARS virus, the Chinese government singled out rural-urban migrants as the priority target. At least 8 urgent directives about migrants were issued by the central government and 16 by Beijing municipality government in April and May 2003. In 2020, however, migrant workers are hardly mentioned. Most measures fighting COVID-19 target the entire population. It is clear that mobility is no longer specific to migrants and has become a generalized feature across society. The meaning of mobility has changed, as has its relation to public health.

There were good reasons why the government targeted migrants in 2003. Rural-urban migrants contributed 14.81 percent of all SARS cases in the peak of the epidemic (Ministry of Health 2003). An estimated 12.6% of all migrants nationwide left cities in the wake of the outbreak (Agriculture Survey Team, National Bureau of Statistics, cited in Ma 2003) and they became the main source of rural infections. In Hebei province in north China for instance, 90 percent of SARS victims were returned migrants (Asahi Shimbun 2003). A Beijing Academy of Social Sciences researcher commented that “the spread of the epidemic caused by the fleeing of migrants from Beijing due to the outbreak, and the explosive growth of SARS cases inside of Beijing caused by the concentration of migrants, for the first time brings migrants’ health issue to public attention in an extremely extraordinarily way.” (Feng 2003: 10).

Chain reactions 

How exactly was the SARS epidemic related to population mobility? My fieldwork at that time suggests that, despite narratives in public media and policy documents, few migrants left the city because of health concerns. Migrants were much less sensitive to the epidemic threat than their urban middle-class counterparts. Migrants’ mobility was a result of a chain reaction. In late April 2003, after two months’ cover up, and under strong pressure from the international community and domestic urban residents, the Chinese government acknowledged the epidemic as a national emergency. Public entertainment venues and construction sites were considered high-risk areas and were shut down overnight. Beijing closed about 70 percent of all restaurants in May (Yang 2003), which put up to 237,300 migrants’ jobs in jeopardy (my estimate based on Xinhua News Agency 2003).  Jobless, migrants had to go home. They became the worst victims of the virus, of economic disruption, and of social stigma. Chain reaction means that the connection between epidemic and migration was mediated by social stratification (Xiang 2003).

Grid reactions

In comparison, the COVID-19 epidemic has triggered grid reactions. Residential communities, districts, cities and even entire provinces act as grids to impose blanket surveillance over all the residents, minimize mobilities, and isolate themselves. In the Chinese administrative system, a grid is a cluster of households, ranging from 50 in the countryside to 1000 in cities. Grid managers (normally volunteers) and grid heads (cadres who receive state salaries) make sure that rubbish is collected on time, cars are parked properly, and no political demonstration is possible. During the outbreak, grid managers visit door to door to check everyone’s temperature, hand out passes which allow one person per household to leave home twice a week and, in the case of collective quarantine, deliver food to the doorstep of all families three times a day.

A grid reaction, just like the COVID-19 virus itself, is highly contagious. Once the central government declared the war on the virus, localities across the nation adopted strict measures, even in remote places with no reported infection. In no time the entire nation put itself under gridlock. Grid reaction is not about community grids only; it refers to an all-out, undifferentiated, war-like strategy. Turning entire hospitals into COVID wards and building barricades around villages are part of the grid reaction too.


Total (im)mobilization is regarded necessary partly because of unprecedented mobility levels in China. Over 3.6 billion Chinese travelled by train and 660 million by air in 2019, compared to 0.95 billion and 87 million respectively in 2003; the number of private motor vehicles increased from 13 million in 2003 to 206 million (CEIC Data 2020). Mobility has increased also because job is casualized. Between 2008 and 2016, the informal sector generated 10 million jobs a year, while stable employment in state owned enterprises and foreign-owned enterprises increased much slower and in fact shrank by nearly 2 million between 2015 and 2016 (Qian 2020: 2). The labor dispatch service was legalized in 2008, which by 2011 accounted for 13.1% of all the jobs nationwide (National Federation of Trade Unions 2012: 35). Dispatch agencies move workers from one project site to another. Many others apart from rural-urban migrants are now moving between places and between jobs. This also means that government can no longer rely on employers as a mediator in monitoring employees. Feasible measures have to target the population in entirety.

Grid reaction can be deeply disruptive

Firstly, just like chain reaction, grid reaction induced unintended movements that may further spread the virus. The Wuhan lock down triggered flights from the city, which is said to have turned Wenzhou into an epicentre outside of Hubei (Yao 2020). Inside Hubei, the shortage of medical resources resulting from the lock down compelled patients to move from hospital to hospital seeking care, often on foot because of the suspension of transport. As grids are based on physical boundaries, grid reaction has also fuelled alarming place-based stigma. Persons originally from infected places, regardless how long they had been away, were locked in at home by neighbours, and were even attacked online. Reports also show rising conflicts between residents and officials due to forced quarantine.

Disruptions in economy are the most obvious. As China’s economy in 2020 is four times that of its 2003 size, and, more importantly, as it plays a central role in global supply chains, any glitch in circulation has far-reaching consequences. But it must be emphasized that those who rely on mobility for their livelihood may suffer the most. Taxi drivers, delivery workers, staff in the logistics and service sectors cannot work without moving, and will have no customers without others on the move. Many of them live on daily wages. Two months’ standing still could be devastating.

Thus a Catch-22 scenario: prevalent mobility leaves the government with few options other than grid reaction, but it at the same time renders such response unbearably disruptive. When Chinese society becomes more mobile, responses to risks appear more crude and clumsy. How can a mobility economy be organized in a more sustainable and equitable matter? This is a fundamental challenge for researchers and policy makers in coming decades.

An earlier version of this blog was published on the COVID-19 Forum on Somatosphere on 6 March 2020

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