Short-term effects of ambient particulate matter (PM1, PM2.5 and PM10) on influenza-like illness in Guangzhou, China.

BACKGROUND: Particulate matter (PM) has been linked to respiratory infections in a growing body of evidence. Studies on the relationship between ILI (influenza-like illness) and PM1 (particulate matter with aerodynamic diameter ≤1 µm) are, however, scarce. The purpose of this study was to investigate the effects of PM on ILI in Guangzhou, China. METHODS: Daily ILI cases, air pollution records (PM1, PM2.5, PM10 and gaseous pollutants), and metrological data between 2014 and 2019 were gathered from Guangzhou, China. To estimate the risk of ILI linked with exposure to PM pollutants, a quasi-Poisson regression was used. Additionally, subgroup analyses stratified by gender, age and season were carried out. RESULTS: For each 10 µg/m3 increase of PM1 and PM2.5 over the past two days (lag01), and PM10 over the past three days (lag02), the relative risks (RR) of ILI were 1.079 (95% confidence interval [CI]: 1.050, 1.109), 1.044 (95% CI: 1.027, 1.062) and 1.046 (95% CI: 1.032, 1.059), respectively. The estimated risks for men and women were substantially similar. The effects of PM pollutants between male and female were basically equivalent. People aged 15-24 years old were more susceptive to PM pollutants. CONCLUSIONS: It implies that PM1, PM2.5 and PM10 are all risk factors for ILI, the health impacts of PM pollutants vary by particle size. Reducing the concentration of PM1 needs to be considered when generating a strategy to prevent ILI.

Effects of different levels of non-pharmaceutical interventions on hand, foot and mouth disease in Guangzhou, China.

BACKGROUND: Non-pharmaceutical interventions (NPIs) against coronavirus disease 2019 (COVID-19) may have suppressed the transmission of other infectious diseases. This study aimed to evaluate the impact of different degrees of NPIs during the COVID-19 pandemic on hand, foot and mouth disease (HFMD) in Guangzhou, China. METHODS: Weekly reported HFMD cases and pathogens information during 2015-2021 in Guangzhou were collected from the China National Notifiable Disease Reporting System. The observed number of HFMD cases in 2020 and 2021 was compared to the average level in the same period during 2015-2019. Then, an interrupted time-series segmented regression analysis was applied to estimate the impact of NPIs on HFMD, such as social distancing, suspension of schools, community management and mask wearing. The effects across different subgroups stratified by gender, children groups and enterovirus subtype of HFMD were also examined. RESULTS: A total of 13,224 and 36,353 HFMD cases were reported in 2020 and 2021, which decreased by 80.80% and 15.06% respectively compared with the average number of cases in the same period during 2015-2019. A significant drop in the number of HFMD cases during time when strict NPIs were applied (relative change: 69.07% [95% confidence interval (CI): 68.84%-69.30%]). The HFMD incidence rebounded to historical levels in 2021 as the lockdown eased. The slightest reduction of HFMD cases was found among children at kindergartens or childcare centres among the three children groups (children at kindergartens or childcare centres: 55.50% [95% CI: 54.96%-56.03%]; children living at home: 72.64% [95% CI: 72.38%-72.89%]; others: 74.06% [95% CI: 73.19%-74.91%]). CONCLUSIONS: The strong NPIs during the COVID-19 epidemic may have a significant beneficial effect on mitigating HFMD. However, the incidence of HFMD rebounded as the NPIs became less stringent. Authorities should consider applying these NPIs during HFMD outbreaks and strengthening personal hygiene in routine prevention.

Recent advances in PCR-free nucleic acid detection for SARS-COV-2.

As the outbreak of Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory disease coronavirus 2 (SARS-COV-2), fast, accurate, and economic detection of viral infection has become crucial for stopping the spread. Polymerase chain reaction (PCR) of viral nucleic acids has been the gold standard method for SARS-COV-2 detection, which, however, generally requires sophisticated facilities and laboratory space, and is time consuming. This review presents recent advances in PCR-free nucleic acid detection methods for SARS-CoV-2, including emerging methods of isothermal amplification, nucleic acid enzymes, electrochemistry and CRISPR.

How to enhance supply chain resilience: a logistics approach

Purpose>Logistics capability is an important enabler of supply chain resilience (SCR). However, few studies have analyzed the underlying influence mechanism of logistics capability on SCR in extreme conditions, such as those of the COVID-19 pandemic. The purpose of this study is to increase understanding of the role of logistics capabilities in constituting a resilient supply chain.Design/methodology/approach>Drawing upon the dynamic capability perspective and contingency theory, the proposed conceptual framework aims to demonstrate the relationship between a firm's logistics capabilities and SCR. Furthermore, the conceptual framework is illustrated by empirical evidence from a case study of a Chinese manufacturing company, which focuses on extracting practical lessons from the COVID-19 pandemic.Findings>The findings suggest that digitalization, innovativeness, and modularization comprise potential mediating pathways for firm logistics capability to affect SCR and government policies, risk management culture, trust and cooperation moderate the effect positively. The potential associations are identified and elucidated by detecting the corresponding strategies and practices of a Chinese manufacturer that performed well amid the COVID-19 pandemic.Practical implications>This study provides specific guidelines for logistics managers to enhance SCR during the COVID-19 pandemic. Seeing SCR as a dynamic capability, the framework is also instructive for manufacturers, supply chain members, and policymakers to achieve the sustained competitive advantage of supply chains.Originality/value>The findings expand the understanding of enhancing SCR in a logistics approach. The empirical validation of propositions in the case study reveals a new vista for research on SCR.

Contact tracing period and epidemiological characteristics of an outbreak of the SARS-CoV-2 Delta variant in Guangzhou.

OBJECTIVES: An outbreak of the SARS-CoV-2 Delta variant occurred in Guangzhou in 2021. This study aimed to identify the transmission dynamics and epidemiological characteristics of the Delta variant outbreak to formulate an effective prevention strategy. METHODS: A total of 13102 close contacts and 69 index cases were collected. The incubation period, serial interval, and time interval from the exposure of close contacts to the symptom onset of cases were estimated. Transmission risks based on the exposure time and various characteristics were also assessed. RESULTS: The mean time from exposure to symptom onset among non-household presymptomatic transmission was 3.83 ± 2.29 days, the incubation period was 5 days, and the serial interval was 3 days. The secondary attack rate was high within 4 days before onset and 4-10 days after symptom onset. Compared with other contact types, household contact had a higher transmission risk. The transmission risk increased with the number and frequency of contact with index cases. Cycle threshold (Ct) values were associated with lower transmission risk (adjusted odds ratio [OR] 0.93 [95% CI 0.88-0.99] for ORF 1ab gene; adjusted OR 0.91 [95% CI 0.86-0.97] for N gene). CONCLUSION: The contact tracing period may need to be extended to 4 days before symptom onset. The low Ct value of index cases, the high number and frequency of contact with index cases, and household contacts were associated with a higher transmission risk of SARS-CoV-2 Delta.

Duration of SARS-CoV-2 positive in quarantine room environments: A perspective analysis.

OBJECTIVE: To determine the duration of SARS-CoV-2 persistence in quarantine hotel environments. METHODS: 39 Patients confirmed by RT-PCR were included. We collected clinical features, laboratory test results, smear sample information, and quarantine room information. Genome sequencing and phylogenetic analysis were conducted. We analyzed the factors associated with environmental contamination. RESULT: Among 39 COVID-19 cases, 10 were asymptomatic and 37 were imported from aboard. We collected 271 swab samples from environmental surfaces related to observational patients. Eighteen swab samples from seven patients were positive. The highest contamination rates occurred on cups (100%), followed by hand sink (12.82%), toilet seat and flush (7.89%), telephone (5.56%), bedside table (5.56%), and floor drain (5.41%). The results showed that environmental surface contamination was associated with the clinical cycle threshold values for patients (P = 0.01) and the sampling interval time after the cases left their rooms (P = 0.03). The duration of environmental surface contamination was associated with the wet status of the sampling site (P = 0.01). CONCLUSION: Our findings showed that environmental contamination might be attributed to the viral load in the respiratory tracts of patients and the sampling interval time after the cases left their rooms. Moist surfaces were more vulnerable to remaining SARS-CoV-2 RNA-positive. Our study highlights the importance of implementing strict chemical disinfection strategies in quarantine rooms.