COVID-19 and Mobility

                                                                                                        Kilkon Ko, 

                                                                                     Prof, Seoul National University

Why Human Mobility Matter?

COVID-19 has severely reduced the mobility of people. The reduction is to some extent because of a travel restriction, but people also voluntarily stay at home to avoid infection. As mobility is crucial for understanding the spread of COVID-19, economic impact, and resilience of social interaction, we should carefully analyze the mobility data.

Data Availability for Mobility Analysis

ARIC has accumulated the different mobility data such as Google Mobility data, Apple Mobility Data, Korea's Highway Traffic Data, Seoul Metropolitan Public Transportation Data, Incheon Airport Traffic Data, etc. Upon the request, ARIC will provide mobility data for academic research.  

Analysis results in the below are based on Google mobility data. Google provides datasets of the percentage change of visits to six places: grocery & pharmacy, parks, transit station, retail & recreation, residential, and workplace. Each place measured covers following areas. 

• Grocery & pharmacy

Mobility trends for places like grocery markets, food warehouses, farmers markets, specialty food shops, drug stores, and pharmacies. 

• Parks: local parks, national parks, public beaches, marinas, dog parks, plazas, and public gardens.

• Transit stations: public transport hubs such as subway, bus, and train stations.

• Retail & recreation: restaurants, cafes, shopping centers, theme parks, museums, libraries, and movie theaters.

• Residential: residence.

• Workplaces: work.

The percentage change is a change from the base mobility measured by the median mobility of the same weekday during five weeks (Jan 3 ~ Feb 6) of each country.  

Korea: Its Uniqueness

Most countries adopted both international and domestic travel bans. However, South Korea did not adopt the mandatory travel bans except city of Wuhan, China and couple of other cities. Within a country, while Daegu was heavily hit by COVID-19, Korean government did not restrict movement of people. Hence, Korea can be a case how COVID-19 can affect voluntarily restriction of mobility of people regardless of government intervention.  

As shown in Figure, the mobility for workplace, retail & recreation, and transit in Korea dropped significantly after Daegu outbreak (Feb 17). The significant drop of the mobility began to recover. In the worst situation, the mobility rate was dropped to 41% on March 1 in case of retail and recreation mobility. However, the mobility had recovered gradually since then. As of March 28, we can find that the level of the mobility for workplace, transit, and retail & recreation is almost the same to that of the base line weeks. 

Such a high resilience of mobility of Korea can play a positive role in the recovery of economic and social relations. 

Not all types of mobility has decreased. As shown in Figure, the mobility for places like the park is more active than the baseline periods. Considering that people suffer from the huge psychological stress due to the fear of pandemic, visiting park can contribute to alleviate the stress of people.   

ASEAN Countries

ASEAN countries show the different of percent change of mobility during the COVID-19 period. For instance, Singapore implemented a very strict travel restriction as a part of her 'circuit breaker" policy announced on April 3. As the result, we can find the very significant drop in the mobility for retail & recreation. The drop has not recovered yet by the end of May. Impressive pattern found in Singapore is that people immediately comply with the travel restrict policy of the government. In the worst situation, the mobility for retail & recreation place was dropped by 70% from the baseline period. 

Similar pattern is also found in Malaysia which implemented the nation-wide movement control order(MOC) since March 18.  

Unlike the Singapore and Malaysia, Vietnam, Cambodia, Laos, and Myanmar show the gradual recovery of mobility. These countries imposed strict travel restrictions and report relatively small infection cases of COVID-19. Despite the low level of infection, it is notable that they experience a significant drop of mobility. In addition, their recovery of mobility for retail & recreation is not as fast as Korea. Most countries still show the lower than 20 percent mobility compared to the baseline period (Jan 3. to Feb 6.). 

The trend of Indonesia is somewhat different from other ASEAN countries in that she does not enter into a recovery stage. The mobility is still staggering since the early April. Such trend is mainly because that the new confirmed cases is still high. 

The slow recovery of mobility is not only a problem to ASEAN countries. Even after five month later of COVID-19 outbreak in China, our world suffers from the severe contraction of mobility. Our mobility level is still 25% lower than the baseline period (Jan. 3 to Feb. 6). 

Risk Cognition and Change in Mobility

In the figure, the red line shows the increase rate of COVID-19 confirmed cases per day(JHU) and the remaining lines shows the amount of movement in workplaces and transit stations. Most ASEAM countries, the amount of movement is decreasing as the increase rate of Confirmed case surges. 

Mobility and Domestic movement restriction policy

Using the data from The Oxford COVID-19 Government Response Tracker (OxCGRT) and Google's mobility reports, we analyzed the status of movement decrease before and after government policy. Only the Mann-Whitney U test between t-2 and t-1 showed significant difference.

As a result of analyzing 10 days before and after the time when the 101 countries government's domestic movement restriction were implemented, it was found that the mobility in workplaces was significantly reduced two days before the government's movement restrictions were implemented.