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Statistical models of processes where random events have an effect on partly random subsequent events are covered in this chapter. The sequence of eruptions of the geyser Old Faithful is taken as a simple example to illustrate Markov Chains. Infectious disease models are then covered and the history of various attempts at modelling them from the early twentieth century onwards is covered. Modelling religious conversion as a stochastic process is treated briefly.
As a result of the COVID-19 pandemic, medical statistics and public health data have become staples of newsfeeds worldwide, with infection rates, deaths, case fatality and the mysterious R figure featuring regularly. However, we don't all have the statistical background needed to translate this information into knowledge. In this lively account, Stephen Senn explains these statistical phenomena and demonstrates how statistics is essential to making rational decisions about medical care. The second edition has been thoroughly updated to cover developments of the last two decades and includes a new chapter on medical statistical challenges of COVID-19, along with additional material on infectious disease modelling and representation of women in clinical trials. Senn entertains with anecdotes, puzzles and paradoxes, while tackling big themes including: clinical trials and the development of medicines, life tables, vaccines and their risks or lack of them, smoking and lung cancer, and even the power of prayer.
Infectious diseases and war are maleficent comrades. This reality applies equally well to the war in Ukraine and the current COVID-19 pandemic. Europe is facing a huge refugee crisis and potentially the conflict could worsen the COVID-19 pandemic. Initially, two major countries of concern are Poland, which has taken the majority of refugees, and Moldova, which has taken a very large number of refugees on a per capita basis. However, the concern extends to the rest of Europe because of the mobility of refugees beyond the first country they enter. Vaccinating, infection control and boosting refugees should be a priority. But whole prevention of COVID-19 is very complex because of other issues related to the success of prevention.
The coronavirus disease 2019 (COVID-19), with new variants, continues to be a constant pandemic threat that is generating socio-economic and health issues in manifold countries. The principal goal of this study is to develop a machine learning experiment to assess the effects of vaccination on the fatality rate of the COVID-19 pandemic. Data from 192 countries are analysed to explain the phenomena under study. This new algorithm selected two targets: the number of deaths and the fatality rate. Results suggest that, based on the respective vaccination plan, the turnout in the participation in the vaccination campaign, and the doses administered, countries under study suddenly have a reduction in the fatality rate of COVID-19 precisely at the point where the cut effect is generated in the neural network. This result is significant for the international scientific community. It would demonstrate the effective impact of the vaccination campaign on the fatality rate of COVID-19, whatever the country considered. In fact, once the vaccination has started (for vaccines that require a booster, we refer to at least the first dose), the antibody response of people seems to prevent the probability of death related to COVID-19. In short, at a certain point, the fatality rate collapses with increasing doses administered. All these results here can help decisions of policymakers to prepare optimal strategies, based on effective vaccination plans, to lessen the negative effects of the COVID-19 pandemic crisis in socioeconomic and health systems.
Selenium is found at the active centre of twenty-five selenoproteins which have a variety of roles, including the well-characterised function of antioxidant defense, but it also is claimed to be involved in the immune system. However, due to limited and conflicting data for different parameters of immune function, intakes of selenium that have an influence on immune function are uncertain. This review covers the relationship between selenium and immune function in man, focusing on the highest level of evidence, namely that generated by randomised controlled trials (RCT), in which the effect of selective administration of selenium, in foods or a supplement, on immune function was assessed. A total of nine RCT were identified from a systematic search of the literature, and some of these trials reported effects on T and natural killer cells, which were dependent on the dose and form of selenium administered, but little effect of selenium on humoral immunity. There is clearly a need to undertake dose–response analysis of cellular immunity data in order to derive quantitative relationships between selenium intake and measures of immune function. Overall, limited effects on immunity emerged from experimental studies in human subjects, though additional investigation on the potential influence of selenium status on cellular immunity appears to be warranted.
Older adults have an increased risk of complications or death from influenza. Despite the benefits of vaccination for older adults, vaccination coverage among older adults ages 65 years and over is still below Canada’s national target of 80 per cent. As health–care-seeking behaviours are influenced by several factors, including life satisfaction, we investigated the relationship between life satisfaction and influenza vaccination among older adults. A sample (n = 22,424) from the 2015–2016 Canadian Community Health Survey data was analysed using descriptive and multinomial logistic regression analyses. Higher life satisfaction was associated with a more recent influenza vaccination history. Vaccination differed by gender, age, and self-reported health status, as women, much older adults, and those with the poorest health status were more likely to be vaccinated. The study suggests an association between life satisfaction and influenza vaccination. More research into the factors that impact influenza vaccination in older adults is needed to increase vaccination coverage in the older adult population.
Introducing susceptible-infected-recovered epidemiology dynamics with vaccines into an endogenous growth model, we investigate the impact of government infectious disease policy on macroeconomic performance. We find that any expenditure that improves health, whether to reduce the contact rate or increase the recovery rate or the vaccination rate, and regardless of whether it comes directly from the households or the government, has a positive impact on economic growth, but does not necessarily improve the welfare. The reason people’s health has improved but their welfare has fallen is because government expenditures must be covered by taxes, which will reduce their disposable income and consumption.
Despite the growing body of evidence suggesting that alcohol consumption is associated with an increased risk of and poorer treatment outcomes from pneumonia, little is known about the association between alcohol control policy and pneumonia mortality. As such, this study aimed to assess the impact of three alcohol control policies legislated in 2008, 2017 and 2018 in Lithuania on sex-specific pneumonia mortality rates among individuals 15+ years of age. An interrupted time-series analysis using a generalised additive mixed model was performed for each policy. Of the three policies, only the 2008 policy resulted in a significant slope change (i.e. decline) in pneumonia mortality rates among males; no significant slope change was observed among females. The low R2 values for all sex-specific models suggest that other external factors are likely also influencing the sex-specific pneumonia mortality rates in Lithuania. Overall, the findings from this study suggest alcohol control policy's targeting affordability may be an effective way to reduce pneumonia mortality rates, among males in particular. However, further research is needed to fully explore their impact.
Pathogens and humans have coexisted for a long time. Studies suggest that, even before recorded history, nomadic populations are likely to have suffered from a plethora of diseases, such as malaria and perhaps yellow fever. The transition to a sedentary lifestyle anchored around small villages, and later on the establishment of large urban centers from Mesopotamia to the Indus Valley and what is modern-day China, paved the way for the increased spread and diversification of these pathogens. High population density, the comingling of humans and animals, and the proliferation of trade routes linking once-distant urban areas enabled viruses, bacteria, and other pathogens to propagate quickly and travel progressively farther. To this day, these dynamics set forth in antiquity continue to play out in similar ways in a world that has become more connected and densely populated.
This chapter argues that (1) explosive population growth is a major factor in the transition to the Anthropocene and (2) the control of infectious disease was the proximate cause of modern population growth. Thus, the changing patterns of mortality should be integrated into narratives of humanity’s takeover of planet earth. It also argues that human expansion (in both pre-modern and modern times) creates the ecological conditions for the emergence of new infectious diseases, and therefore the evolution of novel threats is likely to remain a dimension of life in the Anthropocene for the planet’s dominant species.
This study aimed to assess the health outcome of four epidemic-prone infectious diseases, in the context of a Primary Health Care project implemented in a protracted refugee setting along the Thai–Myanmar border.
Refugees settled at the Thai–Myanmar border are fully dependent on support for health services, shelter, food, education, water, and sanitation. The Non-Governmental Organization Malteser International developed an integrated Primary Health Care program in close cooperation with trained camp residents over 25 years in the two settlements under its supervision. The project has been funded by the European Commission Civil Protection and Humanitarian Aid Operations (DG ECHO).
This was a retrospective primary health care project evaluation. All-cause mortality; morbidity trends in malaria, lower respiratory tract infections (LRTIs), watery diarrhea, and dysentery; and health service utilization covering a time span of 18 years were assessed. Programmatic changes in the Primary Health Care (PHC) project and events with a potential effect on health of the target population were examined.
Despite the continuous drain of trained health care workers, the volatile influx of refugees, and the isolated location of the two camps, the initial basic curative health care developed into an integrated and comprehensive PHC project including a SPHERE-compliant water, sanitation, and hygiene program. Malaria, LRTIs, watery diarrhea, and dysentery morbidity dropped twelve, three, two, and fivefold, respectively, over the 18-year period evaluated while the health services utilization dropped from 7.1 to 2.9 consultations per refugee/year. The international community may face situations where integration of refugees into the health services of the host country is not possible. In such a context, integrated and evidence-based PHC adequately funded and implemented by one health agency is an effective and relevant approach to reduce the infectious diseases burden under the constraints of semipermanent living conditions.
This chapter provides an overview of 20 primary recommendations for safe working in the andrology laboratory, along with sections on accident prevention, appropriate clothing and the proper use of personal protective equipment (PPE), fire safety, dealing with spills, use and disposal of biological materials, chemical hazards, compressed gases, and cryogenics.
Understand how the built environment can affect safety and efficiency outcomes during doffing of personal protective equipment (PPE) in the context of coronavirus disease 2019 (COVID-19) patient care.
We conducted (1) field observations and surveys administered to healthcare workers (HCWs) performing PPE doffing, (2) focus groups with HCWs and infection prevention experts, and (3) a with healthcare design experts.
This study was conducted in 4 inpatient units treating patients with COVID-19, in 3 hospitals of a single healthcare system.
The study included 24 nurses, 2 physicians, 1 respiratory therapist, and 2 infection preventionists.
The doffing task sequence and the layout of doffing spaces varied considerably across sites, with field observations showing most doffing tasks occurring around the patient room door and PPE support stations. Behaviors perceived as most risky included touching contaminated items and inadequate hand hygiene. Doffing space layout and types of PPE storage and work surfaces were often associated with inadequate cleaning and improper storage of PPE. Focus groups and the design charrette provided insights on how design affording standardization, accessibility, and flexibility can support PPE doffing safety and efficiency in this context.
There is a need to define, organize and standardize PPE doffing spaces in healthcare settings and to understand the environmental implications of COVID-19–specific issues related to supply shortage and staff workload. Low-effort and low-cost design adaptations of the layout and design of PPE doffing spaces may improve HCW safety and efficiency in existing healthcare facilities.
The dengue virus type 3 (DENV-3) homotypic outbreak cycles reported in Klang Valley, Malaysia in 1992–1995 and 2002 demonstrated different epidemic magnitude and duration. These outbreak cycles were caused by two closely related strains of viruses within the DENV-3 genotype II (DENV-3/II). The role of viral genotypic diversity and factors that could have influenced this phenomenon were investigated. The serum neutralisation sensitivity of DEN3/II strains responsible for the DENV-3 outbreak cycles in 1992–1995 and 2002 were examined. Representative virus isolates from the respective outbreaks were subjected to virus neutralisation assay using identified sera of patients with homotypic (DENV-3) or heterotypic dengue infections (DENV-1 and DENV-2). Results from the study suggested that isolates representing DENV-3/II group E (DENV-3/II-E) from the 1992–1995 outbreak and DENV-3/II group F (DENV-3/II-F) from the 2002 outbreak were neutralised at similar capacity (intergenotypic differences <2-fold) by sera of patients infected with DENV-3, DENV-1 and DENV-2/Asian genotypes. Sera of the DENV-2/Cosmopolitan infection efficiently neutralised DENV-3/II-F (FRNT50 = 508.0) at a similar neutralisation capacity against its own homotypic serotype, DENV-2 (FRNT50 = 452.5), but not against DENV-3/II-E (FRNT50 = 100.8). The different neutralisation sensitivities of DENV-3/II strains towards the cross-reacting DENV-2 heterotypic immunity could play a role in shaping the DENV-3 recurring outbreaks pattern in Malaysia. Two genetic variations, E-132 (H/Y) and E-479 (A/V) were identified on the envelope protein of DENV-3/II-E and DENV-3/II-F, respectively. The E-132 variation was predicted to affect the protein stability. A more extensive study, however, on the implication of the naturally occurring genetic variations within closely related DENV genotypes on the neutralisation profile and protective immunity would be needed for a better understanding of the DENV spread pattern in a hyperendemic setting.
The COVID-19 pandemic is affecting people worldwide. In Spain, the first wave was especially severe.
This study aimed to identify sources and levels of distress among Spanish primary care physicians (PCPs) during the first wave of the pandemic (April 2020).
A cross-sectional study was conducted using a survey that included sociodemographic data, a description of working conditions related to distress [such as gaps in training in protective measures, cleaning, and hygiene procedures in work setting, unavailability of personal protective equipments (PPEs) and COVID-19 RT-PCR test, and lack of staff due to be infected] and a validated scale, the ‘Self-applied Acute Stress Scale’ (EASE). The survey was answered by a non-probability sampling of PCPs working in family healthcare centres from different regions of Spain. Analysis of variance and multivariate linear regression analysis were performed.
In all, out of 518 PCP participants, 123 (23.7%) obtained high psychological distress scores. Only half of them had received information about the appropriate use of PPE. PCP characteristics associated with higher levels of distress include female gender [1.69; 95% confidence interval (CI) 0.54, 2.84]; lack of training in protective measures (1.96; 95% CI 0.94, 2.99); unavailable COVID-19 RT-PCR for health care workers after quarantine or COVID-19 treatment (−0.77 (−1.52, −0.02). Reinforcing disinfection of the work environment (P < 0.05), availability of PPEs (P < 0.05), and no healthcare professional was infected (P < 0.05) were related to the lowest distress score.
A better understanding of the sources of distress among PCPs could prevent its effect on future outbreaks.
The clinical value of tonsillectomy continues to cause much debate, despite tonsil disease representing a significant burden to patients, caregivers and healthcare systems. This study assessed the long-term effect of adenotonsillectomy or tonsillectomy on the Paediatric Throat Disorders Outcome Test (‘T-14’), a validated tool used to objectively assess obstructive and infective symptoms in paediatric throat disorders.
Patients aged under 16 years undergoing adenotonsillectomy or tonsillectomy were recruited consecutively from 2018 into our prospective observational study. The Paediatric Throat Disorders Outcome Test questionnaire was completed by the children's caregivers pre-operatively (n = 80), and at 21 days (n = 68) and 2 years (n = 66) post-operatively.
Significant reductions were noted in mean total Paediatric Throat Disorders Outcome Test scores at 21 days and 2 years post-operatively (p ≤ 0.003).
Our results provide supporting evidence that paediatric adenotonsillectomy or tonsillectomy significantly improves quality of life up to two years post-operatively, and therefore remains a valuable use of healthcare resources.
Experience gained from responding to major outbreaks may have influenced the early coronavirus disease-2019 (COVID-19) pandemic response in several countries across Africa. We retrospectively assessed whether Guinea, Liberia and Sierra Leone, the three West African countries at the epicentre of the 2014–2016 Ebola virus disease outbreak, leveraged the lessons learned in responding to COVID-19 following the World Health Organization's (WHO) declaration of a public health emergency of international concern (PHEIC). We found relatively lower incidence rates across the three countries compared to many parts of the globe. Time to case reporting and laboratory confirmation also varied, with Guinea and Liberia reporting significant delays compared to Sierra Leone. Most of the selected readiness measures were instituted before confirmation of the first case and response measures were initiated rapidly after the outbreak confirmation. We conclude that the rapid readiness and response measures instituted by the three countries can be attributed to their lessons learned from the devastating Ebola outbreak, although persistent health systems weaknesses and the unique nature of COVID-19 continue to challenge control efforts.
The present study aimed to give an overview of research publications on health system preparedness against viral infectious disease outbreaks.
A bibliometric method was implemented from 2001 to 2020. The studied pathogens were dengue, Ebola, influenza, Zika, Middle East respiratory syndrome (MERS), Severe acute respiratory syndrome (SARS), and coronavirus disease 2019 (COVID-19).
The search query returned 501 documents. The growth of publications showed a sharp peak in 2020 for COVID-19 and 3 small peaks in 2006, 2009, and 2015 for SARS, influenza, and Ebola, respectively. Of the retrieved documents, 208 (41.5%) were on influenza, 164 (32.7%) were on COVID-19, and 83 (16.6%) were on Ebola. Countries in the region of the Americas (n = 221; 44.1%) returned the majority of the documents, while countries in Latin America and the African region returned the least. The United States (n = 197; 39.3%) had a leading role in this field. The US Centers for Disease Control and Prevention (n = 51; 10.2%) ranked first, followed by the Johns Hopkins University (n = 16; 3.2%). The Disaster Medicine and Public Health Preparedness journal (n = 21; 4.2%) ranked first. International research collaboration was relatively inadequate.
Research on preparedness against infectious diseases was episodic. Research collaboration needs to be prioritized for countries with a history of fatal outbreaks.
‘Health‐related stigma’ is typically known as social rejection or exclusion of individuals and populations suffering from specific health problems. Results on previous infectious diseases showed that stigma can be experienced by survivors but also by health‐care workers (HCW). Several factors contribute to stigma associated with infectious diseases, such as people’s knowledge, myths and stories transmitted by the mass and social media and psychosocial variables, such as risk perception and fear of being infected. COVID‐19 is a new disease with many unknown aspects and, naturally, people are afraid of the unknown.
To reflect on infectious diseases and social stigma during covid-19 pandemics.
Pubmed and Google Scholar search.
Stigmatization can considerably increase psychosomatic distress and disturbance and can negatively affect people with infection and those at risk of infection in seeking medical care. HCWs and volunteers working in the field may also become stigmatized, leading to higher rates of distress, stress, and burnout When people avoid groups or geographic areas related to infectious diseases, this can pose significant economic losses. Thus, stigma is more than a mere negative outcome of infectious diseases; it is both a factor that contributes to the epidemics and pandemics and a disease in itself.
Anticipating disease‐related stigma during the COVID‐19 pandemic enables policy‐makers to address it, restricting its adverse effects. The hidden burden caused by this stigma can cause severe consequences for patients, HCW, and public health measures, so, coordinated psychological interventions to overcome this crisis seems essential.