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1.
Sci Rep ; 11(1): 20739, 2021 10 20.
Article in English | MEDLINE | ID: covidwho-1475485

ABSTRACT

Since the first coronavirus disease 2019 (COVID-19) outbreak appeared in Wuhan, mainland China on December 31, 2019, the geographical spread of the epidemic was swift. Malaysia is one of the countries that were hit substantially by the outbreak, particularly in the second wave. This study aims to simulate the infectious trend and trajectory of COVID-19 to understand the severity of the disease and determine the approximate number of days required for the trend to decline. The number of confirmed positive infectious cases [as reported by Ministry of Health, Malaysia (MOH)] were used from January 25, 2020 to March 31, 2020. This study simulated the infectious count for the same duration to assess the predictive capability of the Susceptible-Infectious-Recovered (SIR) model. The same model was used to project the simulation trajectory of confirmed positive infectious cases for 80 days from the beginning of the outbreak and extended the trajectory for another 30 days to obtain an overall picture of the severity of the disease in Malaysia. The transmission rate, ß also been utilized to predict the cumulative number of infectious individuals. Using the SIR model, the simulated infectious cases count obtained was not far from the actual count. The simulated trend was able to mimic the actual count and capture the actual spikes approximately. The infectious trajectory simulation for 80 days and the extended trajectory for 110 days depicts that the inclining trend has peaked and ended and will decline towards late April 2020. Furthermore, the predicted cumulative number of infectious individuals tallies with the preparations undertaken by the MOH. The simulation indicates the severity of COVID-19 disease in Malaysia, suggesting a peak of infectiousness in mid-March 2020 and a probable decline in late April 2020. Overall, the study findings indicate that outbreak control measures such as the Movement Control Order (MCO), social distancing and increased hygienic awareness is needed to control the transmission of the outbreak in Malaysia.


Subject(s)
COVID-19/epidemiology , COVID-19/physiopathology , Public Health Informatics/methods , Computer Simulation , Disease Outbreaks , Disease Susceptibility/epidemiology , Epidemics , Humans , Malaysia , Models, Theoretical , Public Health , Quarantine , SARS-CoV-2
2.
Eur Rev Med Pharmacol Sci ; 25(18): 5876-5884, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1451047

ABSTRACT

The risk stratification of young adults between subjects who will develop a mild form COVID-19 and subjects who will undergo a severe disease remains inaccurate. In this review, we propose that the Barker hypothesis might explain the increased susceptibility to severe forms of COVID-19 in subjects who underwent intrauterine growth restriction (IUGR). In this paper evidence indicating an association between a low birth weight and an adult phenotype which might favor a severe outcome of SARS-CoV-2 infection are presented: lower lung functional capacity; increased respiratory morbidity; changes in fibrinogen and Factor VII serum levels and dysregulation of the hemostasis and thrombosis system; acquisition of a pro-thrombotic phenotype; low nephron number, with decreased ability to sustain renal function and increased renal morbidity; heart remodeling, with a less efficient cardiac function; endothelial dysfunction, a risk factor for the insurgence of the multiple organ failure; remodeling of arteries, with changes in the elastic properties of the arterial wall, predisposing to the insurgence and progression of atherosclerosis; dysfunction of the innate immune system, a risk factor for immune diseases in adulthood. These data suggest that young and adult subjects born too small (IUGR) or too early (pre-terms) might represent a subgroup of "at risk subjects", more susceptible toward severe forms of COVID-19. Given that LBW may be considered a surrogate of IUGR, this phenotypic marker should be included among the indispensable clinical data collected in every patient presenting with SARS-COV-2 infection, irrespectively of his/her age.


Subject(s)
COVID-19/epidemiology , Disease Susceptibility/epidemiology , Fetal Development , Disease Susceptibility/virology , Fetal Growth Retardation , Humans , Infant, Low Birth Weight , Severity of Illness Index , Young Adult
3.
Sci Rep ; 11(1): 18951, 2021 09 23.
Article in English | MEDLINE | ID: covidwho-1437686

ABSTRACT

A spatial susceptible-exposed-infectious-recovered (SEIR) model is developed to analyze the effects of restricting interregional mobility on the spatial spread of the coronavirus disease 2019 (COVID-19) infection in Japan. National and local governments have requested that residents refrain from traveling between prefectures during the state of emergency. However, the extent to which restricting interregional mobility prevents infection expansion is unclear. The spatial SEIR model describes the spatial spread pattern of COVID-19 infection when people commute or travel to a prefecture in the daytime and return to their residential prefecture at night. It is assumed that people are exposed to an infection risk during their daytime activities. The spatial spread of COVID-19 infection is simulated by integrating interregional mobility data. According to the simulation results, interregional mobility restrictions can prevent the geographical expansion of the infection. On the other hand, in urban prefectures with many infectious individuals, residents are exposed to higher infection risk when their interregional mobility is restricted. The simulation results also show that interregional mobility restrictions play a limited role in reducing the total number of infected individuals in Japan, suggesting that other non-pharmaceutical interventions should be implemented to reduce the epidemic size.


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/transmission , Disease Susceptibility/epidemiology , Epidemics , Humans , Japan/epidemiology , Models, Theoretical , SARS-CoV-2/pathogenicity , Transportation/statistics & numerical data , Travel/statistics & numerical data , Travel/trends
4.
Immunity ; 54(10): 2172-2176, 2021 Oct 12.
Article in English | MEDLINE | ID: covidwho-1433404

ABSTRACT

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated disease, coronavirus disease 2019 (COVID-19), has caused a devastating pandemic worldwide. Here, we explain basic concepts underlying the transition from an epidemic to an endemic state, where a pathogen is stably maintained in a population. We discuss how the number of infections and the severity of disease change in the transition from the epidemic to the endemic phase and consider the implications of this transition in the context of COVID-19.


Subject(s)
COVID-19/epidemiology , COVID-19/immunology , Endemic Diseases , COVID-19/prevention & control , Disease Susceptibility/epidemiology , Disease Susceptibility/immunology , Epidemics , Humans , Immunity , Prevalence , SARS-CoV-2/immunology , Severity of Illness Index , Vaccination
5.
PLoS One ; 16(9): e0257354, 2021.
Article in English | MEDLINE | ID: covidwho-1410638

ABSTRACT

In this study, we formulate and analyze a deterministic model for the transmission of COVID-19 and evaluate control strategies for the epidemic. It has been well documented that the severity of the disease and disease related mortality is strongly correlated with age and the presence of co-morbidities. We incorporate this in our model by considering two susceptible classes, a high risk, and a low risk group. Disease transmission within each group is modelled by an extension of the SEIR model, considering additional compartments for quarantined and treated population groups first and vaccinated and treated population groups next. Cross Infection across the high and low risk groups is also incorporated in the model. We calculate the basic reproduction number [Formula: see text] and show that for [Formula: see text] the disease dies out, and for [Formula: see text] the disease is endemic. We note that varying the relative proportion of high and low risk susceptibles has a strong effect on the disease burden and mortality. We devise optimal medication and vaccination strategies for effective control of the disease. Our analysis shows that vaccinating and medicating both groups is needed for effective disease control and the controls are not very sensitive to the proportion of the high and low risk populations.


Subject(s)
Algorithms , Basic Reproduction Number/prevention & control , COVID-19/transmission , Disease Susceptibility/diagnosis , Models, Biological , COVID-19/epidemiology , COVID-19/virology , Computer Simulation , Disease Susceptibility/epidemiology , Epidemics/prevention & control , Humans , Quarantine/methods , Risk Factors , SARS-CoV-2/physiology , Vaccination/methods
6.
PLoS One ; 16(7): e0255438, 2021.
Article in English | MEDLINE | ID: covidwho-1388951

ABSTRACT

Although traditional models of epidemic spreading focus on the number of infected, susceptible and recovered individuals, a lot of attention has been devoted to integrate epidemic models with population genetics. Here we develop an individual-based model for epidemic spreading on networks in which viruses are explicitly represented by finite chains of nucleotides that can mutate inside the host. Under the hypothesis of neutral evolution we compute analytically the average pairwise genetic distance between all infecting viruses over time. We also derive a mean-field version of this equation that can be added directly to compartmental models such as SIR or SEIR to estimate the genetic evolution. We compare our results with the inferred genetic evolution of SARS-CoV-2 at the beginning of the epidemic in China and found good agreement with the analytical solution of our model. Finally, using genetic distance as a proxy for different strains, we use numerical simulations to show that the lower the connectivity between communities, e.g., cities, the higher the probability of reinfection.


Subject(s)
COVID-19/epidemiology , Epidemics/prevention & control , Mutation/genetics , SARS-CoV-2/genetics , China/epidemiology , Disease Susceptibility/epidemiology , Evolution, Molecular , Humans , Models, Statistical , Probability
7.
Thorac Cancer ; 12(20): 2637-2647, 2021 10.
Article in English | MEDLINE | ID: covidwho-1373770

ABSTRACT

Several studies have highlighted that cancer patients tend to be more susceptible to develop severe infection and to die from COVID-19. Certain medical conditions such as immunosuppression, presence of comorbidities, and underlying pulmonary damage are possible determinants of disease severity, especially in lung cancer patients. While recent studies have shown that lung cancer is one of the most prevalent tumor types among COVID-19 cancer patients, we still have an incomplete view of how data from several countries work as a whole. The aim of this review was to investigate COVID-19 prevalence in lung cancer patient cohorts and their probability to develop severe illness and death when compared to nonlung cancer patients from multiple nationalities, including countries that have been the epicenters of the pandemic. We also focus on some intrinsic lung cancer features that might influence COVID-19 outcomes. An integrative view of the susceptibility of lung cancer patients might be especially relevant to assist physicians in evaluating the risks of COVID-19 in these patients, and to foster better decisions on treatment delay.


Subject(s)
COVID-19/complications , COVID-19/diagnosis , Lung Neoplasms/complications , COVID-19/epidemiology , COVID-19/mortality , Comorbidity , Disease Susceptibility/epidemiology , Geography , Humans , Internationality , Lung Neoplasms/epidemiology , Lung Neoplasms/mortality , Prevalence , Risk , SARS-CoV-2 , Severity of Illness Index , Treatment Outcome
10.
Environ Health ; 20(1): 34, 2021 03 26.
Article in English | MEDLINE | ID: covidwho-1154012

ABSTRACT

BACKGROUND: An unusual feature of SARS-Cov-2 infection and the COVID-19 pandemic is that children are less severely affected than adults. This is especially paradoxical given the epidemiological links between poor air quality and increased COVID-19 severity in adults and that children are generally more vulnerable than adults to the adverse consequences of air pollution. OBJECTIVES: To identify gaps in knowledge about the factors that protect children from severe SARS-Cov-2 infection even in the face of air pollution, and to develop a transdisciplinary research strategy to address these gaps. METHODS: An international group of researchers interested in children's environmental health was invited to identify knowledge gaps and to develop research questions to close these gaps. DISCUSSION: Key research questions identified include: what are the effects of SAR-Cov-2 infection during pregnancy on the developing fetus and child; what is the impact of age at infection and genetic susceptibility on disease severity; why do some children with COVID-19 infection develop toxic shock and Kawasaki-like symptoms; what are the impacts of toxic environmental exposures including poor air quality, chemical and metal exposures on innate immunity, especially in the respiratory epithelium; what is the possible role of a "dirty" environment in conveying protection - an example of the "hygiene hypothesis"; and what are the long term health effects of SARS-Cov-2 infection in early life. CONCLUSION: A concerted research effort by a multidisciplinary team of scientists is needed to understand the links between environmental exposures, especially air pollution and COVID-19. We call for specific research funding to encourage basic and clinical research to understand if/why exposure to environmental factors is associated with more severe disease, why children appear to be protected, and how innate immune responses may be involved. Lessons learned about SARS-Cov-2 infection in our children will help us to understand and reduce disease severity in adults, the opposite of the usual scenario.


Subject(s)
COVID-19/epidemiology , Child Health , Environmental Exposure/adverse effects , Environmental Health , Adult , Age Factors , Air Pollution/adverse effects , Air Pollution/prevention & control , COVID-19/immunology , COVID-19/pathology , COVID-19/prevention & control , Child , Disease Susceptibility/epidemiology , Disease Susceptibility/immunology , Disease Susceptibility/pathology , Environmental Exposure/prevention & control , Fetal Development , Humans , Hygiene Hypothesis , Immunity, Innate , Respiratory System/pathology , Respiratory System/virology , SARS-CoV-2
11.
PLoS Comput Biol ; 17(3): e1008763, 2021 03.
Article in English | MEDLINE | ID: covidwho-1140525

ABSTRACT

The interventions and outcomes in the ongoing COVID-19 pandemic are highly varied. The disease and the interventions both impose costs and harm on society. Some interventions with particularly high costs may only be implemented briefly. The design of optimal policy requires consideration of many intervention scenarios. In this paper we investigate the optimal timing of interventions that are not sustainable for a long period. Specifically, we look at at the impact of a single short-term non-repeated intervention (a "one-shot intervention") on an epidemic and consider the impact of the intervention's timing. To minimize the total number infected, the intervention should start close to the peak so that there is minimal rebound once the intervention is stopped. To minimise the peak prevalence, it should start earlier, leading to initial reduction and then having a rebound to the same prevalence as the pre-intervention peak rather than one very large peak. To delay infections as much as possible (as might be appropriate if we expect improved interventions or treatments to be developed), earlier interventions have clear benefit. In populations with distinct subgroups, synchronized interventions are less effective than targeting the interventions in each subcommunity separately.


Subject(s)
COVID-19/epidemiology , COVID-19/prevention & control , Pandemics/prevention & control , SARS-CoV-2 , Basic Reproduction Number/statistics & numerical data , COVID-19/immunology , Computational Biology , Disease Susceptibility/epidemiology , Health Policy , Humans , Immunity, Herd , Mathematical Concepts , Models, Statistical , Pandemics/statistics & numerical data , Prevalence , Time Factors
12.
Epidemics ; 35: 100446, 2021 06.
Article in English | MEDLINE | ID: covidwho-1116595

ABSTRACT

Several independent datasets suggest blood type A is over-represented and type O under-represented among COVID-19 patients. However, blood group antigens appear not to be conventional susceptibility factors in that they do not affect disease severity, and the relative risk to non-O individuals is attenuated when population prevalence is high. Here, I model a scenario in which ABO transfusion incompatibility reduces the chance of a patient transmitting the virus to an incompatible recipient - thus in Western populations type A and AB individuals are "super-recipients" while type O individuals are "super-spreaders". This results in an offset in the timing of the epidemic among individuals of different blood types, and an increased relative risk to type A/AB patients that is most pronounced during early stages of the epidemic. However, once the majority of any given population is infected, the relative risk to each blood type approaches unity. Published data on COVID-19 prevalence from regions in the early stages of the SARS-CoV-2 epidemic suggests that if this model holds true, ABO incompatibility reduces virus transmissibility by at least 60 %. Exploring the implications of this model for vaccination strategies shows that paradoxically, targeted vaccination of either high-susceptibility type A/AB or "super-spreader" type O individuals is less effective than random vaccination at blocking community spread of the virus. Instead, the key is to maintain blood type diversity among the remaining susceptible individuals. Given the good agreement between this model and observational data on disease prevalence, the underlying biochemistry urgently requires experimental investigation.


Subject(s)
ABO Blood-Group System , Blood Group Incompatibility , COVID-19/transmission , Models, Theoretical , Blood Group Incompatibility/blood , Blood Group Incompatibility/epidemiology , COVID-19/blood , COVID-19/epidemiology , Disease Susceptibility/blood , Disease Susceptibility/epidemiology , Humans , Prevalence , Risk , SARS-CoV-2 , Severity of Illness Index
13.
Clin Nutr ; 40(4): 1637-1643, 2021 04.
Article in English | MEDLINE | ID: covidwho-1116485

ABSTRACT

The high prevalence of obesity and obesity-related comorbidities has reached pandemic proportions, particularly in Western countries. Obesity increases the risk to develop several chronic noncommunicable disease, ultimately contributing to reduced survival. Recently, obesity has been recognized as major risk factor for coronavirus disease-19 (COVID-19)-related prognosis, contributing to worse outcomes in those with established COVID-19. Particularly, obesity has been associated with higher hospitalization rates in acute or intensive care and greater risk for invasive mechanical ventilation than lean people. Obesity is characterized by metabolic impairments and chronic low-grade systemic inflammation that causes a pro-inflammatory microenvironment, further aggravating the cytokine production and risk of cytokine storm response during Sars-Cov2 sepsis or other secondary infections. Moreover, the metabolic dysregulations are closely related to an impaired immune system and altered response to viral infection that can ultimately lead to a greater susceptibility to infections, longer viral shedding and greater duration of illness and severity of the disease. In individuals with obesity, maintaining a healthy diet, remaining physically active and reducing sedentary behaviors are particularly important during COVID-19-related quarantine to reduce metabolic and immune impairments. Moreover, such stategies are of utmost importance to reduce the risk for sarcopenia and sarcopenic obesity, and to prevent a reduction and potentially even increase cardiorespiratory fitness, a well-known independent risk factor for cardiovascular and metabolic diseases and recently found to be a risk factor also for hospitalizations secondary to COVID-19. Such lifestyle strategies may ultimately reduce morbility and mortality in patients with infectious disease, especially in those with concomitant obesity. The aim of this review is to discuss how obesity might increase the risk of COVID-19 and potentially affect its prognosis once COVID-19 is diagnosed. We therefore advocate for implementation of strategies aimed at preventing obesity in the first place, but also to minimize the metabolic anomalies that may lead to a compromized immune response and chronic low-grade systemic inflammation, especially in patients with COVID-19.


Subject(s)
COVID-19/epidemiology , Disease Susceptibility/epidemiology , Obesity/epidemiology , Obesity/prevention & control , COVID-19/immunology , Cardiorespiratory Fitness/physiology , Comorbidity , Diet/standards , Disease Susceptibility/immunology , Exercise/physiology , Humans , Obesity/immunology , Prognosis , Risk Factors , SARS-CoV-2 , Severity of Illness Index
14.
JAMA Intern Med ; 181(5): 672-679, 2021 05 01.
Article in English | MEDLINE | ID: covidwho-1098863

ABSTRACT

Importance: Understanding the effect of serum antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on susceptibility to infection is important for identifying at-risk populations and could have implications for vaccine deployment. Objective: The study purpose was to evaluate evidence of SARS-CoV-2 infection based on diagnostic nucleic acid amplification test (NAAT) among patients with positive vs negative test results for antibodies in an observational descriptive cohort study of clinical laboratory and linked claims data. Design, Setting, and Participants: The study created cohorts from a deidentified data set composed of commercial laboratory tests, medical and pharmacy claims, electronic health records, and hospital chargemaster data. Patients were categorized as antibody-positive or antibody-negative according to their first SARS-CoV-2 antibody test in the database. Main Outcomes and Measures: Primary end points were post-index diagnostic NAAT results, with infection defined as a positive diagnostic test post-index, measured in 30-day intervals (0-30, 31-60, 61-90, >90 days). Additional measures included demographic, geographic, and clinical characteristics at the time of the index antibody test, including recorded signs and symptoms or prior evidence of coronavirus 2019 (COVID) diagnoses or positive NAAT results and recorded comorbidities. Results: The cohort included 3 257 478 unique patients with an index antibody test; 56% were female with a median (SD) age of 48 (20) years. Of these, 2 876 773 (88.3%) had a negative index antibody result, and 378 606 (11.6%) had a positive index antibody result. Patients with a negative antibody test result were older than those with a positive result (mean age 48 vs 44 years). Of index-positive patients, 18.4% converted to seronegative over the follow-up period. During the follow-up periods, the ratio (95% CI) of positive NAAT results among individuals who had a positive antibody test at index vs those with a negative antibody test at index was 2.85 (95% CI, 2.73-2.97) at 0 to 30 days, 0.67 (95% CI, 0.6-0.74) at 31 to 60 days, 0.29 (95% CI, 0.24-0.35) at 61 to 90 days, and 0.10 (95% CI, 0.05-0.19) at more than 90 days. Conclusions and Relevance: In this cohort study, patients with positive antibody test results were initially more likely to have positive NAAT results, consistent with prolonged RNA shedding, but became markedly less likely to have positive NAAT results over time, suggesting that seropositivity is associated with protection from infection. The duration of protection is unknown, and protection may wane over time.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19 Serological Testing , COVID-19 , Disease Susceptibility , SARS-CoV-2 , Adult , Age Factors , Antibodies, Viral/isolation & purification , COVID-19/blood , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Nucleic Acid Testing/methods , COVID-19 Nucleic Acid Testing/statistics & numerical data , COVID-19 Serological Testing/methods , COVID-19 Serological Testing/statistics & numerical data , Correlation of Data , Disease Susceptibility/diagnosis , Disease Susceptibility/epidemiology , Disease Susceptibility/immunology , Female , Humans , Male , Middle Aged , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Seroepidemiologic Studies , Symptom Assessment/methods , Symptom Assessment/statistics & numerical data , United States/epidemiology , Virus Shedding/immunology
16.
Horm Mol Biol Clin Investig ; 42(1): 99-104, 2021 Feb 04.
Article in English | MEDLINE | ID: covidwho-1067447

ABSTRACT

The uncontrolled spread of the COVID-19 pandemic which originated in China created a global turmoil. While the world is still busy figuring out a cure for the deadly disease, scientists worked out on many theories and conducted several studies to establish a relationship between the infection and other known diseases. Cardiovascular diseases (CVD) are one of the major complications of this infection after the respiratory manifestations. Individuals with cardiovascular complication are said to be more susceptible to acquiring the infection because the novel coronavirus uses the ACE2 receptor for its entry inside the cell and there is a high level of ACE2 expression in individuals with cardiovascular complications because of the enzyme's anti-hypertrophic, anti-fibrotic and anti-hypertensive effects on the heart. Individuals who belong to the older age group are also more susceptible. Knowing the above information, it might seem that using ACE2 inhibitors would help to slow or prevent the entry of the novel coronavirus but it would also at the same time prove to have deleterious effects on the cardiovascular system as the protective functions of ACE2 would be lost. While the search for a cure still continues it has been stated many a times that the conditions might worsen with time and the only way to keep ourselves and our family safe would be to follow the appropriate social distancing methods and get a COVID test if we experience any of the major symptoms.


Subject(s)
COVID-19/epidemiology , Cardiovascular Diseases/epidemiology , Age Factors , Aged , Aged, 80 and over , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , COVID-19/complications , COVID-19/pathology , COVID-19/therapy , Cardiovascular Diseases/complications , Cardiovascular Diseases/therapy , Comorbidity , Disease Susceptibility/epidemiology , Humans , Middle Aged , Pandemics , Risk Factors , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Virus Internalization/drug effects
17.
JAMA Pediatr ; 175(2): 143-156, 2021 02 01.
Article in English | MEDLINE | ID: covidwho-1064305

ABSTRACT

Importance: The degree to which children and adolescents are infected by and transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The role of children and adolescents in transmission of SARS-CoV-2 is dependent on susceptibility, symptoms, viral load, social contact patterns, and behavior. Objective: To systematically review the susceptibility to and transmission of SARS-CoV-2 among children and adolescents compared with adults. Data Sources: PubMed and medRxiv were searched from database inception to July 28, 2020, and a total of 13 926 studies were identified, with additional studies identified through hand searching of cited references and professional contacts. Study Selection: Studies that provided data on the prevalence of SARS-CoV-2 in children and adolescents (younger than 20 years) compared with adults (20 years and older) derived from contact tracing or population screening were included. Single-household studies were excluded. Data Extraction and Synthesis: PRISMA guidelines for abstracting data were followed, which was performed independently by 2 reviewers. Quality was assessed using a critical appraisal checklist for prevalence studies. Random-effects meta-analysis was undertaken. Main Outcomes and Measures: Secondary infection rate (contact-tracing studies) or prevalence or seroprevalence (population screening studies) among children and adolescents compared with adults. Results: A total of 32 studies comprising 41 640 children and adolescents and 268 945 adults met inclusion criteria, including 18 contact-tracing studies and 14 population screening studies. The pooled odds ratio of being an infected contact in children compared with adults was 0.56 (95% CI, 0.37-0.85), with substantial heterogeneity (I2 = 94.6%). Three school-based contact-tracing studies found minimal transmission from child or teacher index cases. Findings from population screening studies were heterogenous and were not suitable for meta-analysis. Most studies were consistent with lower seroprevalence in children compared with adults, although seroprevalence in adolescents appeared similar to adults. Conclusions and Relevance: In this meta-analysis, there is preliminary evidence that children and adolescents have lower susceptibility to SARS-CoV-2, with an odds ratio of 0.56 for being an infected contact compared with adults. There is weak evidence that children and adolescents play a lesser role than adults in transmission of SARS-CoV-2 at a population level. This study provides no information on the infectivity of children.


Subject(s)
COVID-19/transmission , Disease Susceptibility/epidemiology , Disease Transmission, Infectious/statistics & numerical data , Adolescent , COVID-19/epidemiology , Child , Communicable Disease Control/organization & administration , Disease Transmission, Infectious/prevention & control , Female , Humans , Male , Risk Assessment , Seroepidemiologic Studies
18.
Int J Infect Dis ; 103: 395-401, 2021 Feb.
Article in English | MEDLINE | ID: covidwho-1065176

ABSTRACT

OBJECTIVES: This study aimed to compare the risk of infection of children with that of adults and to explore risk factors of infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) by following up close contacts of COVID-19 patients. METHOD: The retrospective cohort study was performed among close contacts of index cases diagnosed with COVID-19 in Guangzhou, China. Demographic characteristics, clinical symptoms and exposure information were extracted. Logistic regression analysis was employed to explore the risk factors. The restricted cubic spline was conducted to examine to the dose-response relationship between age and SARS-CoV-2 infection. RESULTS: The secondary attack rate (SAR) was 4.4% in 1,344 close contacts. The group of household contacts (17.2%) had the highest SAR. The rare-frequency contact (p < 0.001) and moderate-frequency contact (p < 0.001) were associated with lower risk of infection. Exposure to index cases with dry cough symptoms was associated with infection in close contacts (p = 0.004). Compared with children, adults had a significantly increased risk of infection (p = 0.014). There is a linear positive correlation between age and infection (p = 0.001). CONCLUSIONS: Children are probably less susceptible to COVID-19. Close contacts with frequent contact with patients and those exposed to patients with cough symptoms are associated with an increased risk of infection.


Subject(s)
COVID-19/transmission , Adult , Age Factors , Child , China/epidemiology , Cohort Studies , Contact Tracing , Disease Susceptibility/epidemiology , Epidemics , Family Characteristics , Female , Humans , Incidence , Male , Middle Aged , Retrospective Studies , Risk Factors , SARS-CoV-2
19.
Enferm Clin (Engl Ed) ; 31: S4-S11, 2021 Feb.
Article in Spanish | MEDLINE | ID: covidwho-1065063

ABSTRACT

In January 2020, the Chinese authorities confirmed the causative agent of an outbreak of cases with pneumonia of unknown etiology that appeared in December 2019. The World Health Organization (WHO) called SARS-CoV-2 is a new virus of the coronavirus family. On March 12, the WHO declared this outbreak as a pandemic as it spread worldwide. Human epidemics usually follow the start of exponential growth, this means that from a small number of cases in a few days, a large increase in the number of infected people is observed. The clinical manifestations and spectrum of symptomatic disease range from moderate to critical presentations. In cases with fatal progression, the most serious complications sometimes are cause of a multi-organ failure and patient death. SARS-CoV-2 has a high transmission rate, the route of transmission between humans is through the secretions of infected people, hands or contaminated objects. In general, the epidemic control measures used so far have been based on adoption of interventions from the classical epidemiology, identifying and isolating the cases, following the contacts and establishing restrictions, including quarantine, closure of educational centers, avoiding events in which crowds of people occur, limiting mobility. These measures have been effective in China, the original focus of the outbreak.


Subject(s)
COVID-19/epidemiology , Pandemics , SARS-CoV-2 , COVID-19/complications , COVID-19/prevention & control , COVID-19/transmission , COVID-19 Testing/methods , Contact Tracing , Disease Progression , Disease Susceptibility/epidemiology , Global Health/statistics & numerical data , Humans , Information Dissemination , Models, Theoretical , Multiple Organ Failure/etiology , Pandemics/prevention & control , Physical Distancing , Quarantine , Spain/epidemiology , Symptom Assessment/statistics & numerical data
20.
Viruses ; 13(2)2021 01 22.
Article in English | MEDLINE | ID: covidwho-1045368

ABSTRACT

Since the emergence of COVID-19, many publications have reported associations with ABO blood types. Despite between-study discrepancies, an overall consensus has emerged whereby blood group O appears associated with a lower risk of COVID-19, while non-O blood types appear detrimental. Two major hypotheses may explain these findings: First, natural anti-A and anti-B antibodies could be partially protective against SARS-CoV-2 virions carrying blood group antigens originating from non-O individuals. Second, O individuals are less prone to thrombosis and vascular dysfunction than non-O individuals and therefore could be at a lesser risk in case of severe lung dysfunction. Here, we review the literature on the topic in light of these hypotheses. We find that between-study variation may be explained by differences in study settings and that both mechanisms are likely at play. Moreover, as frequencies of ABO phenotypes are highly variable between populations or geographical areas, the ABO coefficient of variation, rather than the frequency of each individual phenotype is expected to determine impact of the ABO system on virus transmission. Accordingly, the ABO coefficient of variation correlates with COVID-19 prevalence. Overall, despite modest apparent risk differences between ABO subtypes, the ABO blood group system might play a major role in the COVID-19 pandemic when considered at the population level.


Subject(s)
ABO Blood-Group System/blood , COVID-19/blood , Disease Susceptibility/blood , COVID-19/epidemiology , COVID-19/microbiology , Disease Susceptibility/epidemiology , Disease Susceptibility/microbiology , Disease Susceptibility/pathology , Humans , Incidence , Isoantibodies/blood , Microbiota , Odds Ratio , SARS-CoV-2 , Thrombosis/blood , Thrombosis/epidemiology , Thrombosis/microbiology
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