Isolation of cases and contact tracing is used to control outbreaks of infectious diseases, and has been used for coronavirus disease 2019 (COVID-19). Whether this strategy will achieve control ...depends on characteristics of both the pathogen and the response. Here we use a mathematical model to assess if isolation and contact tracing are able to control onwards transmission from imported cases of COVID-19.
We developed a stochastic transmission model, parameterised to the COVID-19 outbreak. We used the model to quantify the potential effectiveness of contact tracing and isolation of cases at controlling a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-like pathogen. We considered scenarios that varied in the number of initial cases, the basic reproduction number (R0), the delay from symptom onset to isolation, the probability that contacts were traced, the proportion of transmission that occurred before symptom onset, and the proportion of subclinical infections. We assumed isolation prevented all further transmission in the model. Outbreaks were deemed controlled if transmission ended within 12 weeks or before 5000 cases in total. We measured the success of controlling outbreaks using isolation and contact tracing, and quantified the weekly maximum number of cases traced to measure feasibility of public health effort.
Simulated outbreaks starting with five initial cases, an R0 of 1·5, and 0% transmission before symptom onset could be controlled even with low contact tracing probability; however, the probability of controlling an outbreak decreased with the number of initial cases, when R0 was 2·5 or 3·5 and with more transmission before symptom onset. Across different initial numbers of cases, the majority of scenarios with an R0 of 1·5 were controllable with less than 50% of contacts successfully traced. To control the majority of outbreaks, for R0 of 2·5 more than 70% of contacts had to be traced, and for an R0 of 3·5 more than 90% of contacts had to be traced. The delay between symptom onset and isolation had the largest role in determining whether an outbreak was controllable when R0 was 1·5. For R0 values of 2·5 or 3·5, if there were 40 initial cases, contact tracing and isolation were only potentially feasible when less than 1% of transmission occurred before symptom onset.
In most scenarios, highly effective contact tracing and case isolation is enough to control a new outbreak of COVID-19 within 3 months. The probability of control decreases with long delays from symptom onset to isolation, fewer cases ascertained by contact tracing, and increasing transmission before symptoms. This model can be modified to reflect updated transmission characteristics and more specific definitions of outbreak control to assess the potential success of local response efforts.
Wellcome Trust, Global Challenges Research Fund, and Health Data Research UK.
To develop the Chinese version of quality of life scale for dry eye patients based on the Impact of Dry Eye on Everyday Life (IDEEL) questionnaire and to assess the reliability and validity of the ...developed scale.
The original IDEEL was adapted cross-culturally to Chinese language and further developed following standard procedures. A total of 100 Chinese patients diagnosed with dry eye syndrome were included to investigate the psychometric properties of the Chinese version of scale. Psychometric tests included internal consistency (Cronbach's ɑ coefficients), construct validity (exploratory factor analysis), and known-groups validity (the analysis of variance).
The Chinese version of Dry Eye Related Quality of Life (CDERQOL) Scale contains 45 items classified into 5 domains. Good to excellent internal consistency reliability was demonstrated for all 5 domains (Cronbach's ɑ coefficients range from 0.716 to 0.913). Construct validity assessment indicated a consistent factorial structure of the CDERQOL scale with hypothesized construct, with the exception of "Dry Eye Symptom-Bother" domain. All domain scores were detected with significant difference across three severity groups of dry eye patients (P < 0.05) except for "Satisfaction with Treatment" domain, indicating good known-groups validity.
The results indicated that the CDERQOL scale is a reliable and valid instrument for patients with dry eye syndrome among Chinese population, and could be used as a supplementary diagnostic and treatment-effectiveness measure.
In most countries, contacts of confirmed COVID-19 cases are asked to quarantine for 14 days after exposure to limit asymptomatic onward transmission. While theoretically effective, this policy places ...a substantial social and economic burden on both the individual and wider society, which might result in low adherence and reduced policy effectiveness. We aimed to assess the merit of testing contacts to avert onward transmission and to replace or reduce the length of quarantine for uninfected contacts.
We used an agent-based model to simulate the viral load dynamics of exposed contacts, and their potential for onward transmission in different quarantine and testing strategies. We compared the performance of quarantines of differing durations, testing with either PCR or lateral flow antigen (LFA) tests at the end of quarantine, and daily LFA testing without quarantine, against the current 14-day quarantine strategy. We also investigated the effect of contact tracing delays and adherence to both quarantine and self-isolation on the effectiveness of each strategy.
Assuming moderate levels of adherence to quarantine and self-isolation, self-isolation on symptom onset alone can prevent 35% (95% uncertainty interval UI 10–59) of onward transmission potential from secondary cases. 14 days of post-exposure quarantine reduces transmission by 48% (95% UI 18–79). Quarantine with release after a negative PCR test 7 days after exposure might avert a similar proportion (50%, 95% UI 23–80; risk ratio RR 1·02, 95% UI 0·88–1·41) to that of the 14-day quarantine period, as would quarantine with a negative LFA test 7 days after exposure (49%, 95% UI 20–78; RR 1·00, 0·82–1·28) or daily LFA testing without quarantine for 5 days after tracing (50%, 95% UI 24–79; RR 1·04, 0·69–1·79) if all tests are returned negative. A stronger effect might be possible if individuals isolate more strictly after a positive test and if contacts can be notified faster.
Testing might allow for a substantial reduction in the length of, or replacement of, quarantine in the control of onwards transmission from contacts of SARS-CoV-2-infected individuals. Decreasing test and trace delays and increasing adherence will further increase the effectiveness of these strategies. Further research is required to empirically evaluate the potential costs (increased transmission risk, false reassurance) and benefits (reduction in the burden of quarantine, increased adherence) of such strategies before adoption as policy.
National Institute for Health Research, UK Research and Innovation, Wellcome Trust, EU Horizon 2021, and the Bill & Melinda Gates Foundation.
To strengthen rural health workforce, the Chinese government has launched a series of policies to promote the job satisfaction of village doctors since the health sector reform. The purpose of this ...mixed-method study is to describe village doctors' job satisfaction under the context of health sector reform and investigate the associated factors.
Data was obtained from a survey of village doctors across three Chinese provinces in 2014. Using a multistage sampling process, quantitative data was collected from village doctors through the self-administered questionnaire and analyzed by multilevel logistic regression models. Qualitative data was collected through face-to-face semi-structured interviews on both village doctors and health managers. Theoretical coding was then conducted to analyze qualitative data.
Among the 1221 respondents, 48.6% felt satisfied with their job. Older village doctors with less of a workload and under high-level integrated management were more likely to feel satisfied with their job. Village doctors who earned the top level of monthly income felt more satisfied, while on the county level, those who lived in counties with the highest GDP felt less satisfied. However, enrollment in a pension plan showed no significant difference in regards to village doctors' job satisfaction. Among 34 participants of qualitative interviews, most believed that age, income, and integrated management had a positive influence on the job satisfaction, while pension plan and basic public health care policies exhibited negative effects. Also, the increasing in availability of healthcare and health resources along with local economic development had negative effects on village doctors' job satisfaction.
Village doctors' job satisfaction was quite low in regards to several determinants including age, income, workload, enrollment in a pension plan, integrated management, and county economic and medical availability development.
Vaccine hesitancy is cited as one of the top threats to global health. The Changchun Changsheng Biotechnology Company was found to have violated good manufacturing practices in July 2018, leading to ...widespread distribution of sub-potent vaccines in China. We estimated the prevalence and determinants of vaccine hesitancy following the Changchun Changsheng vaccine incident (CCVI).
We conducted a cross-sectional survey in China in January 2019, and 2,124 caregivers of children < 6 years old completed self-administered questionnaires. Multinomial logistic regression was used to assess the determinants of vaccine hesitancy; the potential determinants included demographics, socioeconomic status, vaccine confidence, and knowledge of the CCVI. Adjusted Odds Ratios (AORs) and 95% confidence intervals (CI) are reported.
Around 89% of caregivers had heard of the CCVI. Although 83% and 88% of caregivers agreed that vaccines are safe and effective, respectively, 60% expressed some hesitancy about vaccination. Of those hesitant, 26% vaccinated their children at times with doubts, 31% delayed vaccination and 3% refused specific vaccines. Multinomial regression analysis showed that confidence in vaccine safety was associated with a reduced odds of doubts on vaccination (AOR = 0.64; 95%CI = 0.44–0.94), whereas caregivers who had heard of the CCVI had a significantly higher odds of doubts on vaccination (AOR = 1.61; 95%CI = 1.05–2.45). Confidence in the vaccine delivery system and government were associated with a lower odds of vaccine hesitancy. Caregivers with higher education and Buddhism or other religions were significantly more hesitant to vaccinate their children.
Vaccine hesitancy was prevalent following the CCVI. Over half the caregivers either accepted childhood vaccination with doubts or delayed vaccines; only a small number were active refusers. Our findings highlight the importance of addressing vaccine hesitancy, especially following vaccine incidents. Tailored communications are needed to reduce vaccine hesitancy, especially among the highly educated and Buddhist caregivers.
Non-pharmaceutical interventions have been implemented to reduce transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the UK. Projecting the size of an unmitigated epidemic ...and the potential effect of different control measures has been crucial to support evidence-based policy making during the early stages of the epidemic. This study assesses the potential impact of different control measures for mitigating the burden of COVID-19 in the UK.
We used a stochastic age-structured transmission model to explore a range of intervention scenarios, tracking 66·4 million people aggregated to 186 county-level administrative units in England, Wales, Scotland, and Northern Ireland. The four base interventions modelled were school closures, physical distancing, shielding of people aged 70 years or older, and self-isolation of symptomatic cases. We also modelled the combination of these interventions, as well as a programme of intensive interventions with phased lockdown-type restrictions that substantially limited contacts outside of the home for repeated periods. We simulated different triggers for the introduction of interventions, and estimated the impact of varying adherence to interventions across counties. For each scenario, we projected estimated new cases over time, patients requiring inpatient and critical care (ie, admission to the intensive care units ICU) treatment, and deaths, and compared the effect of each intervention on the basic reproduction number, R0.
We projected a median unmitigated burden of 23 million (95% prediction interval 13–30) clinical cases and 350 000 deaths (170 000–480 000) due to COVID-19 in the UK by December, 2021. We found that the four base interventions were each likely to decrease R0, but not sufficiently to prevent ICU demand from exceeding health service capacity. The combined intervention was more effective at reducing R0, but only lockdown periods were sufficient to bring R0 near or below 1; the most stringent lockdown scenario resulted in a projected 120 000 cases (46 000–700 000) and 50 000 deaths (9300–160 000). Intensive interventions with lockdown periods would need to be in place for a large proportion of the coming year to prevent health-care demand exceeding availability.
The characteristics of SARS-CoV-2 mean that extreme measures are probably required to bring the epidemic under control and to prevent very large numbers of deaths and an excess of demand on hospital beds, especially those in ICUs.
Medical Research Council.
The National Health Service (NHS) Pathways triage system collates data on enquiries to 111 and 999 services in England. Since the 18th of March 2020, these data have been made publically available ...for potential COVID-19 symptoms self-reported by members of the public. Trends in such reports over time are likely to reflect behaviour of the ongoing epidemic within the wider community, potentially capturing valuable information across a broader severity profile of cases than hospital admission data. We present a fully reproducible analysis of temporal trends in NHS Pathways reports until 14th May 2020, nationally and regionally, and demonstrate that rates of growth/decline and effective reproduction number estimated from these data may be useful in monitoring transmission. This is a particularly pressing issue as lockdown restrictions begin to be lifted and evidence of disease resurgence must be constantly reassessed. We further assess the correlation between NHS Pathways reports and a publicly available NHS dataset of COVID-19-associated deaths in England, finding that enquiries to 111/999 were strongly associated with daily deaths reported 16 days later. Our results highlight the potential of NHS Pathways as the basis of an early warning system. However, this dataset relies on self-reported symptoms, which are at risk of being severely biased. Further detailed work is therefore necessary to investigate potential behavioural issues which might otherwise explain our conclusions.
China experiences large variations in influenza seasonal activity. We aim to update and improve the current understanding of regional-based within-year variations of influenza activity across ...mainland China to provide evidence for the planning and optimisation of healthcare strategies.
We conducted a systematic review and spatio-temporal meta-analysis to assess regional-based within-year variations of ILI outpatient consultation rates, influenza test positivity rates amongst both ILI outpatients and SARI inpatients, and influenza-associated excess mortality rates. We searched English and Chinese databases for articles reporting time-series data on the four influenza-related outcomes at the sub-national and sub-annual level. After synthesising the data, we reported on the mean monthly rate, epidemic onset, duration, peak and intensity.
We included 247 (7.7%) eligible studies in the analysis. We found within-year influenza patterns to vary across mainland China in relation to latitude and geographic location. High-latitude provinces were characterised by having short and intense annual winter epidemics, whilst most mid-latitude and low-latitude provinces experience semi-annual epidemics or year-round activity. Subtype activity varied across the country, with A/H1N1pdm09 and influenza B occurring predominantly in the winter, whereas A/H3N2 activity exhibited a latitudinal divide with high-latitude regions experiencing a winter peak, whilst mid and low-latitude regions experienced a summer epidemic. Epidemic onsets and peaks also varied, occurring first in the north and later in the southeast. We found positive associations between all influenza health outcomes. In addition, seasonal patterns at the prefecture and county-level broadly resembled their wider province.
This is the first systematic review to simultaneously examine the seasonal variation of multiple influenza-related health outcomes at multiple spatial scales across mainland China. The seasonality information provided here has important implications for the planning and optimisation of immunisation programmes and healthcare provision, supporting the need for regional-based approaches to address variations in local epidemiology.
China's immunization programme is relatively strong, with latest WHO-UNICEF monitoring rates for 2019 showing national vaccination coverage over 90%. However, vaccination coverage is heterogeneous, ...varying across geographic regions, rural-urban communities, and sub-populations. We conducted a qualitative study from a critical realist perspective, analyzing semi-structured interviews with 26 vaccination providers in three provinces, selected to represent regional socioeconomic disparities across Eastern, Central, and Western China. We analyzed data thematically, using deductive and inductive coding. Providers reported vaccination coverage in their areas had increased significantly, but remained lower among migrant and left-behind children. Main coverage determinants were child-related (i.e. gender, number, health status), caregiver-related (i.e. socioeconomic status, role, education level, ethnicity), institution-related (i.e. vaccinator numbers, information system, appointment process), and system-related (i.e. vaccine supply, intersectoral cooperation, vaccine 'hesitancy'). Potentially effective measures to promote vaccination coverage included using routine maternal and child health-care visits for catch-up vaccination, providing additional health education, conducting follow-up family visits by village doctors, and requiring vaccination verification at school enrollment. This is the first qualitative study to examine potential determinants of low vaccination coverage in these areas of China. Findings can inform policies to strengthen the role of schools, develop the national immunization information system, and promote appointment apps. More consideration is needed to improve service quality and eliminating inequities, such as strengthening health education and service provision for migrant and left-behind children.
Access to vaccination information could influence public attitudes towards vaccination. This study investigated the number and types of vaccination-related information sources, and estimated their ...associations with vaccine confidence and hesitancy in China. In January 2019, we conducted a cross-sectional survey in China, and 2122 caregivers with children <6 years completed self-administered questionnaires. Logistic regressions were used to assess associations between caregivers' primary information sources and vaccine confidence/hesitancy. A majority (72%) of caregivers had multiple sources of vaccination-related information. The proportions of caregivers reporting professional sources, media, and peers as primary information sources were 81%, 63%, and 26%. Internal migrants were less likely to get information from professional sources; more educated and wealthier caregivers reported more information sources and were more likely to get information from media and peers. Caregivers who reported professional information sources had significantly higher odds of being confident about the safety of vaccines and lower odds of being hesitant toward vaccination than those who did not. Caregivers who reported the media as a primary information source had significantly higher odds of being hesitant toward vaccination than those who did not. To address vaccine hesitancy, it is essential to promote universal access to professional vaccination-related information sources, and to use the media to disseminate evidence-based information and clarify misinformation. Health communication should target internal migrants, and more educated and wealthier caregivers.
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