ABSTRACT
The ongoing Coronavirus Disease 2019 (COVID-19) has posed a serious threat to human public health and global economy. Population mobility is an important factor that drives the spread of COVID-19. This study aimed to quantitatively evaluate the impact of population flow on the spread of COVID-19 from a spatiotemporal perspective. To this end, a case study was carried out in Hubei Province, which was once the most affected area of COVID-19 outbreak in Mainland China. The geographically and temporally weighted regression (GTWR) model was applied to model the spatiotemporal association between COVID-19 epidemic and population mobility. Two patterns of population flows, including the population inflow from Wuhan and intra-city population movement, were considered to construct explanatory variables. Results indicate that the GTWR model can reveal the spatial-temporal-varying relationships between COVID-19 and population mobility. Moreover, the association between COVID-19 case counts and population movements presented three stages of temporal variation characteristics due to the virus incubation period and implementation of strict lockdown measures. In the spatial dimension, evident geographical disparities were observed across Hubei Province. These findings can provide policymakers useful knowledge about the impact of population movement on the spatio-temporal transmission of COVID-19. Thus, targeted interventions, if necessary in certain time periods, can be implemented to restrict population flow in cities with high transmission risk.
ABSTRACT
In December 2019, a cluster of cases of acute respiratory illness, novel coronavirus-infected pneumonia, occurred in Wuhan, Hubei Province, China. The false-negative nasopharyngeal swabs for SARS-CoV-2 caused delayed diagnosis of COVID-19, which hindered the prevention and control of the pandemic. The transmission risk of SARS-CoV-2 in negative nasopharyngeal swabs cases has rarely been addressed previously. This study evaluated two clusters of COVID-19 in six patients, four of whom (66.7%) tested negative for RNA of SARS-CoV-2 on RT-PCR of nasopharyngeal swabs. All epidemiological, clinical, and laboratory data were collected. The first cluster was a nosocomial infection of four health care providers in early January. One case resulted in a sequential familial cluster of infection. All patients either self-quarantined at home or were admitted to hospital for isolated treatment. All recovered and were anti-SARS-CoV-2 IgG- and/or IgM-positive (100%) for serological detection of SARS-CoV-2 at the recovery stage. Our study provides a cautionary warning that negative results for nasopharyngeal swabs of suspected SARS-CoV-2 infection can increase the risk of nosocomial infection among health care providers. Serologic detection for anti-SARS-CoV-2 IgG and/or IgM is an important test in the diagnosis of COVID-19.