Epidemiological characteristics and environmental risk factors of hemorrhagic fever with renal syndrome in Wei River basin, China, 2005-2015 / 中华流行病学杂志

Objective: To understand the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in Wei River Basin from 2005 to 2015, and analyze the environmental factors that cause the differences of spatial distribution. Methods: HFRS reported cases in Wei River Basin from 2005 to 2015 were collected form "National Disease Reporting Information System" , and the epidemiological features of HFRS were analyzed. Boosted regression trees (BRT) model was applied to evaluate the environment factors on the geographical distribution of HFRS in Wei River basin at 5 km×5 km gird scale. Results: The number of HFRS cases was 18 629, and the average annual incidence from 2005-2015 in Wei River basin was 7.24/100 000. The highest morbidity was 15.18/100 000 in 2012. The middle and lower reaches of Wei River basin had high incidence of HFRS, such as Xi'an, Weinan city. Patients' age was mainly between 16 to 60, and the largest morbidity occured in people over 60 years old. Boosted regression trees modle identified building land, farmland coverage percentage and altitude had higher contribution to the distribution of HFRS. Conclusions: The epidemiological characteristics of HFRS changed significantly. Patients older than 60 years old were having the highest incidence rates. Environmental factors such as buildup land, farmland and altitude played important roles in the geographical distribution of HFRS in the Wei River basin.

Analysis on the spatial-temporal characteristics of hand-foot-mouth disease in Shaanxi province, 2009-2013 / 中华流行病学杂志

Objective: To study the spatial-temporal dynamical features of hand-foot-mouth disease (HFMD) in Shaanxi Province, so as to provide evidence for the development of relative prevention and control programs on HFMD. Methods: Surveillance data of HFMD was collected from the China Information System for Diseases Control and Prevention from 2009 to 2013. Related data on population and gross domestic product (GDP) was obtained from Shaanxi Statistical Yearbook. Statistical tools as R3.4.1, ArcGIS 10.2 and SaTScan 9.2 software were used to describe the spatial-temporal distribution of the disease. Power-law method on spatial-temporal-multicomponent model was used to analyze the spatial-temporal evolution of the HFMD epidemics in Shaanxi Province. Results: A total of 229 904 cases of HFMD were reported in Shaanxi Province from 2009 to 2013, with an average annual incidence as 122.50 per 100 000. Obvious seasonal characteristics were noticed, with 71.71% of the total cases identified between April and July. Counties with high incidence were mainly distributed in the mid-and east parts of Guanzhong area. Through temporal and spatial scan statistics, we identified that ClassⅠ clustering area was fixed to the central and southeast regions of Shaanxi province which were around Xi'an City between 2009 and 2013, with the relative risk (RR) as 2.24, ranging from 2.18 to 3.08. Results from Power-law analysis showed that the continuous follow-up impact from the previous HFMD epidemics appeared strong in Tongguan, Pucheng districts of Weinan City and Weiyang district of Xi'an, with autoregressive components as 1.14, 0.97 and 0.89, respectively. The risk of HFMD seemed high in Huayin city, Changan and Yanta districts and with the endemic components as 5.08, 4.12 and 4.08, respectively. Impact of the epidemics on nearby districts was largely seen in Lianhu district of Xi'an, Wugong district of Xianyang and Gaoling district of Xi'an with epidemic components as 2.12, 2.08 and 1.77, respectively. The etiological constituents of HFMD were mainly Enterovirus 71 between 2009 and 2012, while HFMD was mainly caused by other entero-viruses, in 2013. Conclusion: Significant spatial-temporal heterogeneity of HFMD was seen in Shaanxi province, which called for specific strategies to be developed in the highly endemic areas.

Epidemiological features of hepatitis C and its related influencing factors in Shandong province, 2007-2016 / 中华流行病学杂志

Objective: To analyze the epidemiological characteristics, dynamic trend of development and related influencing factors of hepatitis C in Shandong, China, 2007-2016, also to provide epidemiological evidence for prevention and control of HCV. Methods: National surveillance data of hepatitis C from 2007 to 2016 in Shandong was used, with distribution and clustering map of hepatitis C drawn at the county level. Panel Poisson regression was used to explore the influencing factors of hepatitis C at the city level. Results: The incidence of hepatitis C in Shandong increased from 1.49/100 000 in 2007 to 4.72/100 000 in 2016, with the high incidence mainly clustered in the urban regions in Jinan, Zibo, Weihai et al. and surrounding vicinities. Majority of the cases were young adults, with 53.16% (14 711/27 671) of them being farmers. Results from the Multiple panel Poisson regression analysis indicated that factors as: population density (aIRR=1.07, 95%CI: 1.05-1.10), number of hospital per hundred thousand people shared (aIRR=1.16, 95%CI: 1.08-1.24), expenditure of medical fee in rural (aIRR=1.21, 95%CI: 1.08-1.37) and the proportion of the tertiary industry (aIRR=1.08, 95%CI: 1.07-1.09) were all correlated to the incidence of hepatitis C. Conclusions: The incidence of hepatitis C had been increasing rapidly in recent years, in Shandong. Prevention and control of HCV should focus on high risk population. In addition, rural, especially in areas with lower economics provision should be under more attentions, so as to find more concealed cases for early treatment.

Prevalence, awareness, treatment and control of hypertension in population older than 15 years of age in Beijing, 2013-2014 / 中华流行病学杂志

Objective: To investigate the rates on prevalence, awareness, treatment and control of hypertension in population older than 15 years of age in Beijing, 2013-2014. Methods: A cross-sectional survey was conducted in Beijing between 2013-2014. Stratified multistage random sampling method was used to select representative sample of 13 057 Chinese individuals aged over 15 years, from the general population. Blood pressure was measured for three readings at sitting position after resting for at least five minutes with an average reading recorded. A standardized structured questionnaire was developed to collect history of hypertension and antihypertensive treatment. Results: A total of 4 663 community residents aged over 15 years were hypertensive among the 13 057 individuals, with the standardized prevalence rate as 32.7%, in Beijing area. The age-standardized prevalence rates of hypertension appeared 34.6% in men and 30.8% in women. The age-and sexstandardized prevalence of hypertension rates were 33.3% in urban and 24.6% in rural areas. The prevalence of hypertension increased with age and appeared higher in men than in women, in urban than in rural residents. Among the hypertensive patients, rates of awareness, treatment and control were 66.8%, 64.6% and 31.6%, respectively. Conclusion: High prevalence of hypertension with low rates on awareness and treatment and control, appeared in the general population of Beijing. Related strategies should be developed regarding prevention, control and management of hypertension, to reduce the burden of this disease.

SARS-CoV-2 Shedding Dynamics Across the Respiratory Tract, Sex, and Disease Severity for Adult and Pediatric COVID-19

BackgroundSARS-CoV-2 shedding dynamics in the upper (URT) and lower respiratory tract (LRT) remain unclear. ObjectiveTo analyze SARS-CoV-2 shedding dynamics across COVID-19 severity, the respiratory tract, sex and age cohorts (aged 0 to 17 years, 18 to 59 years, and 60 years or older). DesignSystematic review and pooled analyses. SettingMEDLINE, EMBASE, CENTRAL, Web of Science Core Collection, medRxiv and bioRxiv were searched up to 20 November 2020. ParticipantsThe systematic dataset included 1,266 adults and 136 children with COVID-19. MeasurementsCase characteristics (COVID-19 severity, age and sex) and quantitative respiratory viral loads (rVLs). ResultsIn the URT, adults with severe COVID-19 had higher rVLs at 1 DFSO than adults (P = 0.005) or children (P = 0.017) with nonsevere illness. Between 1-10 DFSO, severe adults had comparable rates of SARS-CoV-2 clearance from the URT as nonsevere adults (P = 0.479) and nonsevere children (P = 0.863). In the LRT, severe adults showed higher post-symptom-onset rVLs than nonsevere adults (P = 0.006). In the analyzed period (4-10 DFSO), severely affected adults had no significant trend in SARS-CoV-2 clearance from LRT (P = 0.105), whereas nonsevere adults showed a clear trend (P < 0.001). After stratifying for disease severity, sex and age (including child vs. adult) were not predictive of the duration of respiratory shedding. LimitationLimited data on case comorbidities and few samples in some cohorts. ConclusionHigh, persistent LRT shedding of SARS-CoV-2 characterized severe COVID-19 in adults. After symptom onset, severe cases tended to have higher URT shedding than their nonsevere counterparts. Disease severity, rather than age or sex, predicted SARS-CoV-2 kinetics. LRT specimens should more accurately prognosticate COVID-19 severity than URT specimens. Primary Funding SourceNatural Sciences and Engineering Research Council.

Heterogeneity in transmissibility and shedding SARS-CoV-2 via droplets and aerosols

Which virological factors mediate overdispersion in the transmissibility of emerging viruses remains a longstanding question in infectious disease epidemiology. Here, we use systematic review to develop a comprehensive dataset of respiratory viral loads (rVLs) of SARS-CoV-2, SARS-CoV-1 and influenza A(H1N1)pdm09. We then comparatively meta-analyze the data and model individual infectiousness by shedding viable virus via respiratory droplets and aerosols. Our analyses indicate heterogeneity in rVL as an intrinsic virological factor facilitating greater overdispersion for SARS-CoV-2 in the COVID-19 pandemic than A(H1N1)pdm09 in the 2009 influenza pandemic. For COVID-19, case heterogeneity remains broad throughout the infectious period, including for pediatric and asymptomatic infections. Hence, many COVID-19 cases inherently present minimal transmission risk, whereas highly infectious individuals shed tens to thousands of SARS-CoV-2 virions/min via droplets and aerosols while breathing, talking and singing. Coughing increases the contagiousness, especially in close contact, of symptomatic cases relative to asymptomatic ones. Infectiousness tends to be elevated between 1-5 days post-symptom onset. Our findings show how individual case variations influence virus transmissibility and present considerations for disease control in the COVID-19 pandemic. Significance StatementFor some emerging infectious diseases, including COVID-19, few cases cause most secondary infections. Others, like influenza A(H1N1)pdm09, spread more homogenously. The virological factors that mediate such distinctions in transmissibility remain unelucidated, prohibiting the development of specific disease control measures. We find that intrinsic case variation in respiratory viral load (rVL) facilitates overdispersion, and superspreading, for COVID-19 but more homogeneous transmission for A(H1N1)pdm09. We interpret the influence of heterogeneity in rVL on individual infectiousness by modelling likelihoods of shedding viable virus via respiratory droplets and aerosols. We analyze the distribution and kinetics of SARS-CoV-2 rVL, including across age and symptomatology subgroups. Our findings compare individual infectiousness across COVID-19 and A(H1N1)pdm09 cases and present quantitative guidance on triaging COVID-19 contact tracing.

Transmission of aerosols through pristine and reprocessed N95 respirators

During the Covid-19 pandemic, pristine and reprocessed N95 respirators are crucial equipment towards limiting nosocomial infections. The NIOSH test certifying the N95 rating, however, poorly simulates aerosols in healthcare settings, limiting our understanding of the exposure risk for healthcare workers wearing these masks, especially reprocessed ones. We used experimental conditions that simulated the sizes, densities and airflow properties of infectious aerosols in healthcare settings. We analyzed the penetration and leakage of aerosols through pristine and reprocessed N95 respirators. Seven reprocessing methods were investigated. Our findings suggest that pristine and properly reprocessed N95 respirators effectively limit exposure to infectious aerosols, but that care must be taken to avoid the elucidated degradation mechanisms and limit noncompliant wear.