scholarly journals Retarded Logistic Equation as a Universal Dynamic Model for the Spread of COVID-19

Author(s):  
B Shayak ◽  
Mohit M Sharma

ABSTRACTIn this work we propose the retarded logistic equation as a dynamic model for the spread of COVID-19 all over the world. This equation accounts for asymptomatic transmission, pre-symptomatic or latent transmission as well as contact tracing and isolation, and leads to a transparent definition of the instantaneous reproduction number R. For different parameter values, the model equation admits different classes of solutions. These solution classes correspond to, inter alia, containment of the outbreak via public health measures, exponential growth despite public health measures, containment despite reopening and second wave following reopening. We believe that the spread of COVID in every localized area such as a city, district or county can be accounted for by one of our solution classes. In regions where R > 1 initially despite aggressive epidemic management efforts, we find that if the mitigation measures are sustained, then it is still possible for R to dip below unity when far less than the region’s entire population is affected, and from that point onwards the outbreak can be driven to extinction in time. We call this phenomenon partial herd immunity. Our analysis indicates that COVID-19 is an extremely vicious and unpredictable disease which poses unique challenges for public health authorities, on account of which “case races” among various countries and states do not serve any purpose and present delusive appearances while ignoring significant determinants.

Author(s):  
Thomas Plümper ◽  
Eric Neumayer

AbstractBackgroundThe Robert-Koch-Institute reports that during the summer holiday period a foreign country is stated as the most likely place of infection for an average of 27 and a maximum of 49% of new SARS-CoV-2 infections in Germany.MethodsCross-sectional study on observational data. In Germany, summer school holidays are coordinated between states and spread out over 13 weeks. Employing a dynamic model with district fixed effects, we analyze the association between these holidays and weekly incidence rates across 401 German districts.ResultsWe find effects of the holiday period of around 45% of the average district incidence rates in Germany during their respective final week of holidays and the 2 weeks after holidays end. Western states tend to experience stronger effects than Eastern states. We also find statistically significant interaction effects of school holidays with per capita taxable income and the share of foreign residents in a district’s population.ConclusionsOur results suggest that changed behavior during the holiday season accelerated the pandemic and made it considerably more difficult for public health authorities to contain the spread of the virus by means of contact tracing. Germany’s public health authorities did not prepare adequately for this acceleration.


2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
G Leiras ◽  
A Martins

Abstract Background Articulation between Civil Protection and Public Health authorities is of paramount importance to control, reduce and prevent threats to the health of the population in situations of crisis or catastrophes. National Civil Protection Authority produces Emergency Plans which describe the role of every stakeholder in emergency situations. Role and importance of Public Health and Public Health Authorities is not always present or well described and known amongst stakeholders. Methods Data was collected from all Districtal Emergency Plans (n = 18). Each document was analysed considering time frame, refences to Public Health and Health Authorities, definition of roles, communication channels, coordination and inclusion of intersectoral communication flow. Quantitative analysis included absolute and relative frequencies and qualitative analysis to all parts related to the terms “Public Health” and “Health Authority”. Each document was reviewed by 2 independent researchers. Results From 18 Districtal Emergency Plans (DEP) analysed, 94,4% (n = 17) had references to Public Health, but none referred the role of Public Health Officers. Only 16,7% referred to Health Authorities, although 94,4% mentioned the law 135/2013, defining the role and attributes of Health Authority. In 72,2%, coordination of Public Health Measures was attributed to the National Medical Emergency Institute. Epidemiological surveillance and Public Health Emergencies were referred in 55,6%, and attributed to the Regional Administration of Health. Conclusions Public Health Authorities and Public Health Medical Officers role in articulation with National Civil Protection Authority in emergency situations lacks severely, with this role being replaced by other entities. This is of great concern regarding management and control of diseases, particularly communicable diseases. Key messages Public Health Authorities lack the necessary involvement in Emergency Plans and emergency situations. Public health measures are coordinated by other entities rather than Public Health Authorities.


10.2196/27882 ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. e27882
Author(s):  
Britt Elise Bente ◽  
Jan Willem Jaap Roderick van 't Klooster ◽  
Maud Annemarie Schreijer ◽  
Lea Berkemeier ◽  
Joris Elmar van Gend ◽  
...  

Background Adoption and evaluation of contact tracing tools based on information and communications technology may expand the reach and efficacy of traditional contact tracing methods in fighting COVID-19. The Dutch Ministry of Health, Welfare and Sports initiated and developed CoronaMelder, a COVID-19 contact tracing app. This app is based on a Google/Apple Exposure Notification approach and aims to combat the spread of the coronavirus among individuals by notifying those who are at increased risk of infection due to proximity to someone who later tests positive for COVID-19. The app should support traditional contact tracing by faster tracing and greater reach compared to regular contact tracing procedures. Objective The main goal of this study is to investigate whether the CoronaMelder is able to support traditional contact tracing employed by public health authorities. To achieve this, usability tests were conducted to answer the following question: is the CoronaMelder user-friendly, understandable, reliable and credible, and inclusive? Methods Participants (N=44) of different backgrounds were recruited: youth with varying educational levels, youth with an intellectual disability, migrants, adults (aged 40-64 years), and older adults (aged >65 years) via convenience sampling in the region of Twente in the Netherlands. The app was evaluated with scenario-based, think-aloud usability tests and additional interviews. Findings were recorded via voice recordings, observation notes, and the Dutch User Experience Questionnaire, and some participants wore eye trackers to measure gaze behavior. Results Our results showed that the app is easy to use, although problems occurred with understandability and accessibility. Older adults and youth with a lower education level did not understand why or under what circumstances they would receive notifications, why they must share their key (ie, their assigned identifier), and what happens after sharing. In particular, youth in the lower-education category did not trust or understand Bluetooth signals, or comprehend timing and follow-up activities after a risk exposure notification. Older adults had difficulties multitasking (speaking with a public health worker and simultaneously sharing the key in the app). Public health authorities appeared to be unprepared to receive support from the app during traditional contact tracing because their telephone conversation protocol lacks guidance, explanation, and empathy. Conclusions The study indicated that the CoronaMelder app is easy to use, but participants experienced misunderstandings about its functioning. The perceived lack of clarity led to misconceptions about the app, mostly regarding its usefulness and privacy-preserving mechanisms. Tailored and targeted communication through, for example, public campaigns or social media, is necessary to provide correct information about the app to residents in the Netherlands. Additionally, the app should be presented as part of the national coronavirus measures instead of as a stand-alone app offered to the public. Public health workers should be trained to effectively and empathetically instruct users on how to use the CoronaMelder app.


Author(s):  
Dillon Adam ◽  
Peng Wu ◽  
Jessica Wong ◽  
Eric Lau ◽  
Tim Tsang ◽  
...  

Abstract Superspreading events have characterised previous epidemics of severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) infections. Using contact tracing data, we identified and characterized SARS-CoV-2 clusters in Hong Kong. Given a superspreading threshold of 6-8 secondary cases, we identified 5-7 probable superspreading events and evidence of substantial overdispersion in transmissibility, and estimated that 20% of cases were responsible for 80% of local transmission. Among terminal cluster cases, 27% (45/167) ended in quarantine. Social exposures produced a greater number of secondary cases compared to family or work exposures (p<0.001) while delays between symptom onset and isolation did not reliably predict the number of individual secondary cases or resulting cluster sizes. Public health authorities should focus on rapid tracing and quarantine of contacts, along with physical distancing to prevent superspreading events in high-risk social environments.


2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Jay Bhattacharya ◽  
Mikko Packalen

Throughout the COVID-19 epidemic, public health authorities have promoted contact tracing as a key tool to combat the spread of the SARS-CoV-2 virus. Jay Bhattacharya and Mikko Packalen argue that contact tracing does not deserve the central place it has received in the tool kit public health authorities use to control the virus, and that, in some cases, it may make an outbreak worse.


2021 ◽  
Author(s):  
Jeremy David Gretton ◽  
Ethan Andrew Meyers ◽  
Alexander C. Walker ◽  
Jonathan Albert Fugelsang ◽  
Derek J. Koehler

During the COVID-19 pandemic, public health messaging, including guidance regarding protective health behavior (e.g., use of non-medical masks), changed over time. Although many revisions were a result of gains in scientific understanding, we nonetheless hypothesized that making changes in guidance salient would negatively impact evaluations of experts and health-protective intentions. In Study 1 (N = 300), we demonstrate that describing COVID-19 guidance in terms of inconsistency (versus consistency) leads people to perceive scientists and public health authorities less favorably (e.g., as less expert). Among a Canadian subsample, making guidance change salient also reduced intentions to download the COVID Alert contact tracing app. In Study 2 (N = 1399), we show that a brief forewarning intervention mitigates detrimental effects of changes in guidance. In the absence of forewarning, emphasizing inconsistency harmed judgments of public health authorities and reduced health-protective intentions, but forewarning eliminated this effect.


2006 ◽  
Vol 11 (12) ◽  
pp. 7-8 ◽  
Author(s):  
P Guglielmetti ◽  
D Coulombier ◽  
G G Thinus ◽  
F Van Loock ◽  
S Schreck

Under Decision 2119/98/EC of the European Parliament and of the Council, a network for epidemiological surveillance and control of communicable diseases in the Community was set up in 1998. One pillar of Decision 2119/98/EC is the early warning and response system (EWRS). The main objective of the network is to establish permanent communication between European Union (EU) Member States’ public health authorities, which are responsible for determining the measures required to control communicable disease-related events. Since 1998, a web based informatics tool has been developed in order to allow information to be shared between the relevant public health authorities. Between 1998 and December 2005, a total of 583 messages were circulated through the EWRS, notifying 396 events. The information shared through the system helped to coordinate public health measures in the EU. However, only few events prompted specific measures at Community level and most of them were controlled with public health measures applied at national level. Major events (such as the Severe Acute Respiratory Syndrome) and the results of simulation exercises prompted the Commission to upgrade the informatics system on the basis of user needs. Since 1 May 2004 the 10 newest Member States have provided information under the current legislation and since April 2005 the European Centre for Disease Prevention and Control (ECDC) is part of the system. Future developments will include a link between the existing EWRS and the communication platform currently developed by the ECDC.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Raynell Lang ◽  
Jamie L. Benham ◽  
Omid Atabati ◽  
Aidan Hollis ◽  
Trevor Tombe ◽  
...  

Abstract Background Public support of public health measures including physical distancing, masking, staying home while sick, avoiding crowded indoor spaces and contact tracing/exposure notification applications remains critical for reducing spread of COVID-19. The aim of our work was to understand current behaviours and attitudes towards public health measures as well as barriers individuals face in following public health measures. We also sought to identify attitudes persons have regarding a COVID-19 vaccine and reasons why they may not accept a vaccine. Methods A cross-sectional online survey was conducted in August 2020, in Alberta, Canada in persons 18 years and older. This survey evaluated current behaviours, barriers and attitudes towards public health measures and a COVID-19 vaccine. Cluster analysis was used to identify key patterns that summarize data variations among observations. Results Of the 60 total respondents, the majority of persons were always or often physically distancing (73%), masking (65%) and staying home while sick (67%). Bars/pubs/lounges or nightclubs were visited rarely or never by 63% of respondents. Persons identified staying home while sick to provide the highest benefit (83%) in reducing spread of COVID-19. There were a large proportion of persons who had not downloaded or used a contact tracing/exposure notification app (77%) and who would not receive a COVID-19 vaccine when available (20%) or were unsure (12%). Reporting health authorities as most trusted sources of health information was associated with greater percentage of potential uptake of vaccine but not related to contact tracing app download and use. Individuals with lower concern of getting and spreading COVID-19 showed the least uptake of public health measures except for avoiding public places such as bars. Lower concern regarding COVID-19 was also associated with more negative responses to taking a potential COVID-19 vaccine. Conclusion These results suggest informational frames and themes focusing on individual risks, highlighting concern for COVID-19 and targeting improving trust for health authorities may be most effective in increasing public health measures. With the ultimate goal of preventing spread of COVID-19, understanding persons’ attitudes towards both public health measures and a COVID-19 vaccine remains critical to addressing barriers and implementing targeted interventions and messaging to improve uptake.


2021 ◽  
Vol 104 (4) ◽  
pp. 1493-1494
Author(s):  
Esteban Ortiz-Prado ◽  
Aquiles R. Henriquez-Trujillo ◽  
Ismar A. Rivera-Olivero ◽  
Byron Freire-Paspuel ◽  
Alexander Paolo Vallejo-Janeta ◽  
...  

ABSTRACTRural communities from Latin America are particularly susceptible to develop serious outbreaks of infectious diseases. Inadequate diagnosis and poor health infrastructure jeopardize proper contact tracing and other actions to reduce the impact of COVID-19 in the region. We herein describe the preliminary data of our ongoing fieldwork of massive testing among nonhospitalized rural population in Manabi Province of the coastal region of Ecuador. A total of 1,479 people from six different rural communities were tested for SARS-CoV-2 by RT-qPCR following the CDC protocol; 350 individuals tested positive, resulting in an overall attack rate of 23.7% for SARS-CoV-2 infection. This ultrahigh prevalence must urge to the public health authorities from Ecuador to take immediate actions to counteract this dramatic scenario in Manabi Province and to improve SARS-CoV-2 testing countrywide.


2019 ◽  
Vol 24 (19) ◽  
Author(s):  
Sebastian Thole ◽  
Daniela Kalhoefer ◽  
Maria an der Heiden ◽  
Doris Nordmann ◽  
Inka Daniels-Haardt ◽  
...  

When a person with contagious measles has travelled by aircraft, European guidelines recommend contact tracing of passengers and crew within 5 days of exposure for post-exposure prophylaxis (PEP), and within 12 days of exposure for informing passengers and crew, in order to prevent further transmissions. To be effective, contact tracing requires prompt diagnosis, immediate notification of public health authorities and rapid availability of passenger contact data. We report two events of contact tracing initiated in Germany after two individuals with measles travelled on three international flights. In one event, contact tracing was initiated late because laboratory confirmation of a clinically diagnosed measles case was awaited unnecessarily. Accessing passenger contact data was difficult in both events because of data protection issues with the airline which was not based in Germany. In both events, passengers were not reached in time to provide PEP, and one event resulted in at least two secondary measles cases. As all passengers were reached before the incubation period ended, tertiary cases were most probably prevented. Public health authorities and the transport sector must collaborate to resolve competing legal regulations for infection prevention and data protection, to simplify and accelerate identification of air travellers exposed to communicable diseases.


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