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1.
J Infect ; 2021 Apr 22.
Article in English | MEDLINE | ID: covidwho-1198894

ABSTRACT

OBJECTIVES: mask-wearing outside the home has been almost universal in Hong Kong since late January 2020 with very high compliance. Nevertheless, community spread of COVID-19 has still occurred. We aimed to assess the settings where COVID-19 transmission occurred and determine the fraction of transmission events that occurred in settings where masks are not usually worn. METHODS: we reviewed detailed information provided by the Hong Kong Department of Health on local COVID-19 cases diagnosed up to 30 September 2020 to determine the most likely settings in which transmission occurred. We classified them in probably mask-on or mask-of and compared the prevalence of asymptomatic infections in these settings. RESULTS: among the 2425 cases (65.3%, 2425/3711) with information on transmission setting, 77.6% of the transmission occurred in household and social settings where face masks are not usually worn. Infections that occurred in mask-on settings were more likely to be asymptomatic (adjusted odds ratio 1.33; 95% confidence interval: 1.04, 1.68). CONCLUSIONS: we conclude that universal mask-wearing can reduce transmission, but transmission can continue to occur in settings where face masks are not usually worn. The higher proportion of asymptomatic cases in mask-on settings could be related to a milder disease presentation or earlier case detection.

2.
J Infect Dis ; 2021 Apr 15.
Article in English | MEDLINE | ID: covidwho-1185676

ABSTRACT

BACKGROUND: Early in the COVID-19 pandemic, there was a concern over possible increase in antibiotic use due to co-infections among COVID-19 patients in the community. Here, we evaluate the changes in nationwide use of broad-spectrum antibiotics during the COVID-19 epidemic in South Korea. METHODS: We obtained national reimbursement data on the prescription of antibiotics, including penicillin with beta-lactamase inhibitors, cephalosporins, fluoroquinolones, and macrolides. We examined the number of antibiotic prescriptions compared with the previous three years in the same period from August to July. To quantify the impact of the COVID-19 epidemic on antibiotic use, we developed a regression model adjusting for changes of viral acute respiratory tract infections (ARTIs) which are an important factor driving antibiotic use. RESULTS: During the COVID-19 epidemic in South Korea, the broad-spectrum antibiotic use dropped by 15%-55% compared to the previous 3 years. Overall reduction in antibiotic use adjusting for ARTIs was estimated to be 14%-30%, with a larger impact in children. CONCLUSIONS: Our study found that broad-spectrum antibiotic use was substantially reduced during the COVID-19 epidemic in South Korea. This reduction can be in part due to reduced ARTIs as a result of stringent public health interventions including social distancing measures.

3.
Lancet Infect Dis ; 2020 Oct 06.
Article in English | MEDLINE | ID: covidwho-1162009

ABSTRACT

BACKGROUND: Middle East respiratory syndrome (MERS) remains of global public health concern. Dromedary camels are the source of zoonotic infection. Over 70% of MERS coronavirus (MERS-CoV)-infected dromedaries are found in Africa but no zoonotic disease has been reported in Africa. We aimed to understand whether individuals with exposure to dromedaries in Africa had been infected by MERS-CoV. METHODS: Workers slaughtering dromedaries in an abattoir in Kano, Nigeria, were compared with abattoir workers without direct dromedary contact, non-abattoir workers from Kano, and controls from Guangzhou, China. Exposure to dromedaries was ascertained using a questionnaire. Serum and peripheral blood mononuclear cells (PBMCs) were tested for MERS-CoV specific neutralising antibody and T-cell responses. FINDINGS: None of the participants from Nigeria or Guangdong were MERS-CoV seropositive. 18 (30%) of 61 abattoir workers with exposure to dromedaries, but none of 20 abattoir workers without exposure (p=0·0042), ten non-abattoir workers or 24 controls from Guangzhou (p=0·0002) had evidence of MERS-CoV-specific CD4+ or CD8+ T cells in PBMC. T-cell responses to other endemic human coronaviruses (229E, OC43, HKU-1, and NL-63) were observed in all groups with no association with dromedary exposure. Drinking both unpasteurised camel milk and camel urine was significantly and negatively associated with T-cell positivity (odds ratio 0·07, 95% CI 0·01-0·54). INTERPRETATION: Zoonotic infection of dromedary-exposed individuals is taking place in Nigeria and suggests that the extent of MERS-CoV infections in Africa is underestimated. MERS-CoV could therefore adapt to human transmission in Africa rather than the Arabian Peninsula, where attention is currently focused. FUNDING: The National Science and Technology Major Project, National Institutes of Health.

4.
Emerg Infect Dis ; 27(5): 1527-1529, 2021 05.
Article in English | MEDLINE | ID: covidwho-1148279

ABSTRACT

A fast-spreading severe acute respiratory syndrome coronavirus 2 variant identified in the United Kingdom in December 2020 has raised international alarm. We analyzed data from 15 countries and estimated that the chance that this variant was imported into these countries by travelers from the United Kingdom by December 7 is >50%.

5.
EClinicalMedicine ; : 100743, 2021 Feb 13.
Article in English | MEDLINE | ID: covidwho-1084574

ABSTRACT

Background: The timing of administration of agents and use of combination treatments in COVID-19 remain unclear. We assessed the effectiveness of therapeutics in cohorts in Hong Kong SAR and Anhui, China. Methods: We conducted propensity-score analysis of 4771 symptomatic patients from Hong Kong between 21st January and 6th December 2020, and 648 symptomatic patients from Anhui between 1st January and 27th February 2020. We censored all observations as at 13st December 2020. Time from hospital admission to discharge, and composite outcome of death, invasive mechanical ventilation or intensive care unit admission across 1) all therapeutic options including lopinavir-ritonavir, ribavirin, umifenovir, interferon-alpha-2b, interferon-beta-1b, corticosteroids, antibiotics, and Chinese medicines, and 2) four interferon-beta-1b combination treatment groups were investigated. Findings: Interferon-beta-1b was associated with an improved composite outcome (OR=0.55, 95%CI 0.38, 0.80) and earlier discharge (-8.8 days, 95%CI -9.7, -7.9) compared to those not administered interferon-beta-1b. Oral ribavirin initiated within 7 days from onset was associated with lower risk of the composite outcome in Hong Kong (OR=0.51, 95%CI 0.29, 0.90). Lopinavir-ritonavir, intravenous ribavirin, umifenovir, corticosteroids, interferon-alpha-2b, antibiotics or Chinese medicines failed to show consistent clinical benefit. Interferon-beta-1b co-administered with ribavirin was associated with improved composite outcome (OR=0.50, 95%CI 0.32, 0.78) and earlier discharge (-2.35 days, 95%CI -3.65, -1.06) compared to interferon-beta-1b monotherapy. Interpretation: Our findings support the early administration of interferon-beta-1b alone or in combination with oral ribavirin for COVID-19 patients. Funding: Hong Kong Health and Medical Research Fund; Hong Kong Innovation and Technology Commission; Chinese Fundamental Research Funds for the Central Universities.

6.
Clin Infect Dis ; 2020 Jun 18.
Article in English | MEDLINE | ID: covidwho-1044767

ABSTRACT

BACKGROUND: Knowledge on the epidemiological features and transmission patterns of COVID-19 is accumulating. Detailed line-list data with household settings can advance the understanding of COVID-19 transmission dynamics. METHODS: A unique database with detailed demographic characteristics, travel history, social relationships, and epidemiological timelines for 1,407 transmission pairs that formed 643 transmission clusters in mainland China was reconstructed from 9,120 COVID-19 confirmed cases reported during January 15 - February 29, 2020. Statistical model fittings were used to identify the super-spreaders and estimate serial interval distributions. Age and gender-stratified hazard of infection were estimated for household versus non-household transmissions. RESULTS: There were 34 primary cases identified as super-spreaders, with 5 super-spreading events occurred within households. Mean and standard deviation of serial intervals were estimated as 5.0 (95% CrI: 4.4, 5.5) and 5.2 (95% CrI: 4.9, 5.7) days for household transmissions and 5.2 (95% CrI: 4.6, 5.8) and 5.3 (95% CrI: 4.9, 5.7) days for non-household transmissions, respectively. Hazard of being infected outside of households is higher for age between 18 and 64 years, whereas hazard of being infected within households is higher for young and old people. CONCLUSIONS: Non-negligible frequency of super-spreading events, short serial intervals, and a higher risk of being infected outside of households for male people of working age indicate a significant barrier to the identification and management of COVID-19 cases, which requires enhanced non-pharmaceutical interventions to mitigate this pandemic.

7.
Preprint | SSRN | ID: ppcovidwho-4829

ABSTRACT

Background: Since the first case of pandemic COVID-19 in South Korea, identified on 19 January 2020, two epidemic waves have occurred We characterised the epidemiology, transmission dynamics and effectiveness of control measures in each epidemic wave of COVID-19 Methods: We analysed publicly available data on confirmed cases of COVID-19 outside of Daegu-Gyeongbuk Regions in South Korea during first (19 January–19 April 2020) and second (20 April–11 August 2020) epidemic waves Transmissibility of SARS-CoV-2 was measured by daily effective reproductive number, Rt Frequencies of cluster types, age-specific transmission probability matrices, proportion of asymptomatic and unlinked cases, and serial interval distribution were estimated for each wave Results: In early May, within 2-weeks of relaxation on strict social distancing measures, Rt increased rapidly from 0 2 to 2 3 within a week and was around 1 until early July The most frequent clusters type were the religious related activities in both waves, but noticed more workplace-related clusters in the second wave The proportion of asymptomatic cases at presentation increased from 22% during first wave to 27% during second wave The proportion of unlinked local cases were similar in both waves (22% and 24%) Transmissions among same age were more common, and children were rarely infectors or infectees The mean serial interval were similar (~3 days) in both waves Conclusions: Our study shows that relaxing social distancing measures was associated with increased SARS-CoV-2 transmission Enhanced contact tracing including asymptomatic cases could be more efficient with social distancing to control further waves of the pandemic

8.
Clin Infect Dis ; 2021 Jan 06.
Article in English | MEDLINE | ID: covidwho-1012825

ABSTRACT

BACKGROUND: Disparities were marked in previous pandemics, usually with higher attack rates reported for those in lower socioeconomic positions and for ethnic minorities. METHODS: We examined characteristics of laboratory-confirmed COVID-19 cases in Hong Kong, assessed associations between incidence and population-level characteristics at the level of small geographic areas, and evaluated relations between socioeconomics and work-from-home (WFH) arrangements. RESULTS: The largest source of COVID-19 importations switched from students studying overseas in the second wave to foreign domestic helpers in the third. The local cases were mostly individuals not in formal employment (retirees and homemakers) and production workers who were unable to WFH. For every 10% increase in the proportion of population employed as executives or professionals in a given geographic region, there was an 84% (95% confidence interval (CI): 1% to 97%) reduction in the incidence of COVID-19 during the third wave. In contrast, in the first two waves, the same was associated with 3.69 times (95% CI: 1.02 to 13.33) higher incidence. Executives and professionals were more likely to implement WFH and experienced frequent changes in WFH practice, compared to production workers. CONCLUSIONS: Consistent findings on the reversed socioeconomic patterning of COVID-19 burden between infection waves in Hong Kong at both individual and population level analyses indicated that risks of infections may be related to occupations involving high exposure frequency and WFH flexibility. Contextual determinants should be taken into account in policy planning aiming at mitigating such disparities.

9.
Nat Commun ; 12(1): 63, 2021 01 04.
Article in English | MEDLINE | ID: covidwho-1007631

ABSTRACT

The SARS-CoV-2 pandemic poses the greatest global public health challenge in a century. Neutralizing antibody is a correlate of protection and data on kinetics of virus neutralizing antibody responses are needed. We tested 293 sera from an observational cohort of 195 reverse transcription polymerase chain reaction (RT-PCR) confirmed SARS-CoV-2 infections collected from 0 to 209 days after onset of symptoms. Of 115 sera collected ≥61 days after onset of illness tested using plaque reduction neutralization (PRNT) assays, 99.1% remained seropositive for both 90% (PRNT90) and 50% (PRNT50) neutralization endpoints. We estimate that it takes at least 372, 416 and 133 days for PRNT50 titres to drop to the detection limit of a titre of 1:10 for severe, mild and asymptomatic patients, respectively. At day 90 after onset of symptoms (or initial RT-PCR detection in asymptomatic infections), it took 69, 87 and 31 days for PRNT50 antibody titres to decrease by half (T1/2) in severe, mild and asymptomatic infections, respectively. Patients with severe disease had higher peak PRNT90 and PRNT50 antibody titres than patients with mild or asymptomatic infections. Age did not appear to compromise antibody responses, even after accounting for severity. We conclude that SARS-CoV-2 infection elicits robust neutralizing antibody titres in most individuals.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , /immunology , Adolescent , Adult , Animals , Antibodies, Viral/blood , /epidemiology , Chlorocebus aethiops , Cohort Studies , Female , Hong Kong/epidemiology , Humans , Male , Middle Aged , Neutralization Tests , Pandemics , Vero Cells , Young Adult
10.
Epilepsy Behav ; 115: 107497, 2021 02.
Article in English | MEDLINE | ID: covidwho-977227

ABSTRACT

This is a territory-wide study to investigate the impact of coronavirus disease 2019 (COVID-19) pandemic on Accident and Emergency Department (A&E) attendances and acute ward admissions for seizures. Adult patients who presented to the A&E with seizures from January 23, 2020 to March 24, 2020 (study period) were included and compared with parallel intervals from 2015 to 2019 (control periods). Preexisting time trend in control periods and potential changes during COVID-19 were analyzed by Poisson, negative and logistic regression models. Accident and Emergency Department attendances and ward admissions for seizures decreased significantly during the COVID-19 pandemic. A total of 319 and 230 recorded ward admissions and A&E attendances for seizures were identified during the study period in 2020, compared with 494 and 343 per annum, respectively in the control periods. The ratio of acute ward admission per A&E attendance for seizures did not change significantly. Intensive care utility and mortality rates remained stable. For some patients, delaying medical attention due to fear of nosocomial COVID-19 cross-infection may lead to severe or even life-threatening consequences. This change in medical help-seeking behavior calls for new medical care models to meet the service gap. Education to patients with epilepsy and their caregivers is of utmost importance during this pandemic.


Subject(s)
/epidemiology , Emergency Service, Hospital/trends , Patient Acceptance of Health Care , Patient Admission/trends , Seizures/epidemiology , Seizures/therapy , Adult , Female , Hong Kong/epidemiology , Hospitalization/trends , Humans , Male , Pandemics/prevention & control
11.
J Formos Med Assoc ; 2020 Nov 21.
Article in English | MEDLINE | ID: covidwho-949911

ABSTRACT

A territory-wide retrospective observational study was conducted in Hong Kong between January 23 to April 22, 2020 to demonstrate changes in pediatric seizure-related accident and emergency department (A&E) visits during the COVID-19 pandemic. Parallel periods from 2015 to 2019 were used as control. All-cause A&E attendances in all paediatric age groups decreased significantly during the study period. Seizure-related attendances decreased across all pediatric age-groups in 2020 (RR 0.379, 95% CI 0.245-0.588), with a disproportionately large decrease in the 0-6 years age group (RR 0.303, 95% CI 0.174-0.526) compared with the 7-18 years age group (RR 0.534, 95% CI 0.393-0.719). Decrease in RTI-related A&E attendances was also more drastic in the 0-6 age group. The two time trends are congruent in the 0-6 years but not the 7-18 years age group. Such a trend is suggestive of the usefulness of infection control measures in seizure prevention, especially amongst young children.

13.
Preprint | SSRN | ID: ppcovidwho-1929

ABSTRACT

Background: Hong Kong was one of the first locations outside of mainland China to identify COVID-19 cases in January 2020 We assessed the impact of various pu

14.
Nat Med ; 26(11): 1714-1719, 2020 11.
Article in English | MEDLINE | ID: covidwho-780024

ABSTRACT

Superspreading events (SSEs) have characterized previous epidemics of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) infections1-6. For SARS-CoV-2, the degree to which SSEs are involved in transmission remains unclear, but there is growing evidence that SSEs might be a typical feature of COVID-197,8. Using contact tracing data from 1,038 SARS-CoV-2 cases confirmed between 23 January and 28 April 2020 in Hong Kong, we identified and characterized all local clusters of infection. We identified 4-7 SSEs across 51 clusters (n = 309 cases) and estimated that 19% (95% confidence interval, 15-24%) of cases seeded 80% of all local transmission. Transmission in social settings was associated with more secondary cases than households when controlling for age (P = 0.002). Decreasing the delay between symptom onset and case confirmation did not result in fewer secondary cases (P = 0.98), although the odds that an individual being quarantined as a contact interrupted transmission was 14.4 (95% CI, 1.9-107.2). Public health authorities should focus on rapidly tracing and quarantining contacts, along with implementing restrictions targeting social settings to reduce the risk of SSEs and suppress SARS-CoV-2 transmission.

16.
Nat Med ; 26(9): 1491-1493, 2020 Sep.
Article in English | MEDLINE | ID: covidwho-705524

ABSTRACT

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

17.
Res Sq ; 2020 Jun 01.
Article in English | MEDLINE | ID: covidwho-669637

ABSTRACT

Studies of novel coronavirus disease (COVID-19) have reported varying estimates of epidemiological parameters such as serial intervals and reproduction numbers. By compiling a unique line-list database of transmission pairs in mainland China, we demonstrated that serial intervals of COVID-19 have shortened substantially from a mean of 7.8 days to 2.6 days within a month. This change is driven by enhanced non-pharmaceutical interventions, in particular case isolation. We also demonstrated that using real-time estimation of serial intervals allowing for variation over time would provide more accurate estimates of reproduction numbers, than by using conventional definition of fixed serial interval distributions. These findings are essential to improve the assessment of transmission dynamics, forecasting future incidence, and estimating the impact of control measures.

18.
Science ; 369(6507): 1106-1109, 2020 08 28.
Article in English | MEDLINE | ID: covidwho-658227

ABSTRACT

Studies of novel coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have reported varying estimates of epidemiological parameters, including serial interval distributions-i.e., the time between illness onset in successive cases in a transmission chain-and reproduction numbers. By compiling a line-list database of transmission pairs in mainland China, we show that mean serial intervals of COVID-19 shortened substantially from 7.8 to 2.6 days within a month (9 January to 13 February 2020). This change was driven by enhanced nonpharmaceutical interventions, particularly case isolation. We also show that using real-time estimation of serial intervals allowing for variation over time provides more accurate estimates of reproduction numbers than using conventionally fixed serial interval distributions. These findings could improve our ability to assess transmission dynamics, forecast future incidence, and estimate the impact of control measures.


Subject(s)
Basic Reproduction Number , Betacoronavirus , Coronavirus Infections/epidemiology , Coronavirus Infections/transmission , Patient Isolation , Pneumonia, Viral/epidemiology , Pneumonia, Viral/transmission , China/epidemiology , Forecasting , Humans , Incidence , Pandemics , Time Factors
19.
Clin Infect Dis ; 70(5): 850-858, 2020 Feb 14.
Article in English | MEDLINE | ID: covidwho-326398

ABSTRACT

BACKGROUND: Respiratory virus-laden particles are commonly detected in the exhaled breath of symptomatic patients or in air sampled from healthcare settings. However, the temporal relationship of detecting virus-laden particles at nonhealthcare locations vs surveillance data obtained by conventional means has not been fully assessed. METHODS: From October 2016 to June 2018, air was sampled weekly from a university campus in Hong Kong. Viral genomes were detected and quantified by real-time reverse-transcription polymerase chain reaction. Logistic regression models were fitted to examine the adjusted odds ratios (aORs) of ecological and environmental factors associated with the detection of virus-laden airborne particles. RESULTS: Influenza A (16.9% [117/694]) and influenza B (4.5% [31/694]) viruses were detected at higher frequencies in air than rhinovirus (2.2% [6/270]), respiratory syncytial virus (0.4% [1/270]), or human coronaviruses (0% [0/270]). Multivariate analyses showed that increased crowdedness (aOR, 2.3 [95% confidence interval {CI}, 1.5-3.8]; P < .001) and higher indoor temperature (aOR, 1.2 [95% CI, 1.1-1.3]; P < .001) were associated with detection of influenza airborne particles, but absolute humidity was not (aOR, 0.9 [95% CI, .7-1.1]; P = .213). Higher copies of influenza viral genome were detected from airborne particles >4 µm in spring and <1 µm in autumn. Influenza A(H3N2) and influenza B viruses that caused epidemics during the study period were detected in air prior to observing increased influenza activities in the community. CONCLUSIONS: Air sampling as a surveillance tool for monitoring influenza activity at public locations may provide early detection signals on influenza viruses that circulate in the community.

20.
Lancet Public Health ; 5(5): e289-e296, 2020 05.
Article in English | MEDLINE | ID: covidwho-96229

ABSTRACT

BACKGROUND: When a new infectious disease emerges, appropriate case definitions are important for clinical diagnosis and for public health surveillance. Tracking case numbers over time is important to establish the speed of spread and the effectiveness of interventions. We aimed to assess whether changes in case definitions affected inferences on the transmission dynamics of coronavirus disease 2019 (COVID-19) in China. METHODS: We examined changes in the case definition for COVID-19 in mainland China during the first epidemic wave. We used exponential growth models to estimate how changes in the case definitions affected the number of cases reported each day. We then inferred how the epidemic curve would have appeared if the same case definition had been used throughout the epidemic. FINDINGS: From Jan 15 to March 3, 2020, seven versions of the case definition for COVID-19 were issued by the National Health Commission in China. We estimated that when the case definitions were changed, the proportion of infections being detected as cases increased by 7·1 times (95% credible interval [CrI] 4·8-10·9) from version 1 to 2, 2·8 times (1·9-4·2) from version 2 to 4, and 4·2 times (2·6-7·3) from version 4 to 5. If the fifth version of the case definition had been applied throughout the outbreak with sufficient testing capacity, we estimated that by Feb 20, 2020, there would have been 232 000 (95% CrI 161 000-359 000) confirmed cases in China as opposed to the 55 508 confirmed cases reported. INTERPRETATION: The case definition was initially narrow and was gradually broadened to allow detection of more cases as knowledge increased, particularly milder cases and those without epidemiological links to Wuhan, China, or other known cases. These changes should be taken into account when making inferences on epidemic growth rates and doubling times, and therefore on the reproductive number, to avoid bias. FUNDING: Health and Medical Research Fund, Hong Kong.


Subject(s)
Coronavirus Infections/epidemiology , Coronavirus Infections/transmission , Epidemics , Pneumonia, Viral/epidemiology , Pneumonia, Viral/transmission , Public Health Surveillance/methods , China/epidemiology , Coronavirus Infections/diagnosis , Humans , Models, Theoretical , Pandemics , Pneumonia, Viral/diagnosis
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