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Association between COVID-19 and Male Fertility: Systematic Review and Meta-Analysis of Observational Studies.
Wang, S, Zhang, A, Pan, Y, Liu, L, Niu, S, Zhang, F, Liu, X
The world journal of men's health. 2023;41(2):311-329
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Several studies have been published documenting possible relationships between Covid-19 and male infertility, but it remains unclear whether Covid-19 affects sperm quality and sex hormones. This meta-analysis and systematic review of observational studies aimed to determine any relationship between Covid-19 infection and male fertility. The results showed that Covid-19 decreased sperm count, sperm concentration, motility, but had no effect on semen volume, immotility, normal morphology or nonprogressive sperm motility. Infection also affected some hormone levels and that effects on hormones were dependent on age of infection onset. Covid-19 infection with or without fever also differentially affected outcomes with those with fever having reduced sperm concentration and progressive sperm motility, which was not seen in those who did not experience fever. Disease severity also affected outcomes with those with moderate Covid-19 having reduced sperm motility, which was not seen in individuals who had mild disease. It was concluded that Covid-19 infection reduced sperm quality and disrupted sex hormones. This study could be used by healthcare professionals to understand that Covid-19 infection may affect the fertility of men.
Abstract
PURPOSE Whether COVID-19 reduces male fertility remains requires further investigation. This meta-analysis and systematic review evaluated the impact of COVID-19 on male fertility. MATERIALS AND METHODS The literature in PubMed, Embase, MEDLINE, Web of Science, and Cochrane Library up to January 01, 2022 was systematically searched, and a meta-analysis was conducted to investigate the effect of COVID-19 on male fertility. Totally 17 studies with a total of 1,627 patients and 1,535 control subjects were included in our meta-analysis. RESULTS Regarding sperm quality, COVID-19 decreased the total sperm count (p=0.012), sperm concentration (p=0.001), total motility (p=0.001), progressive sperm motility (p=0.048), and viability (p=0.031). Subgroup analyses showed that different control group populations did not change the results. It was found that during the illness stage of COVID-19, semen volume decreased, and during the recovery stage of COVID-19, sperm concentration and total motility decreased <90 days. We found that sperm concentration and total motility decreased during recovery for ≥90 days. Fever because of COVID-19 significantly reduced sperm concentration and progressive sperm motility, and COVID-19 without fever ≥90 days, the sperm total motility and progressive sperm motility decreased. Regarding disease severity, the moderate type of COVID-19 significantly reduced sperm total motility, but not the mild type. Regarding sex hormones, COVID-19 increased prolactin and estradiol. Subgroup analyses showed that during the illness stage, COVID-19 decreased testosterone (T) levels and increased luteinizing hormone levels. A potential publication bias may have existed in our meta-analysis. CONCLUSIONS COVID-19 in men significantly reduced sperm quality and caused sex hormone disruption. COVID-19 had long-term effects on sperm quality, especially on sperm concentration and total motility. It is critical to conduct larger multicenter studies to determine the consequences of COVID-19 on male fertility.
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Age-Dependent Relationships Between Disease Risk and Testosterone Levels: Relevance to COVID-19 Disease.
Muehlenbein, M, Gassen, J, Nowak, T, Henderson, A, Morris, B, Weaver, S, Baker, E
American journal of men's health. 2023;17(2):15579883221130195
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A growing body of research finds that in men, testosterone levels may be prognostic of clinical outcomes related to coronavirus disease 2019 (COVID-19 disease). The presence of pre-existing chronic conditions in many patients with COVID-19 disease further complicates the relationship among testosterone and severe outcomes. The aim of this study was to examine whether pre-existing conditions for severe COVID-19 disease were related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. This study obtained data from men (n = 142) who participated in the longitudinal study Waco COVID Survey. All data included in the study was collected as part of the initial intake survey and first laboratory appointment. Results show that serum-free testosterone levels decreased as a function of age. In fact, greater burden of pre-existing conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. Furthermore, in men older than 40 years of age the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Authors conclude that their findings add important insights into the complex role of androgens in chronic and infectious diseases and contribute to the growing body of literature on the relationship between chronic disease and men’s testosterone levels.
Abstract
Testosterone levels in men appear to be prognostic of a number of disease outcomes, including severe COVID-19 disease. Testosterone levels naturally decline with age and are lower in individuals with a number of comorbidities and chronic conditions. Low testosterone may therefore be both a cause and a consequence of illness, including COVID-19 disease. The present project examines whether preexisting conditions for severe COVID-19 disease were themselves related to serum-free testosterone levels in men who had not been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. A clinical risk score for severe COVID-19 disease was computed based on the results of previously published meta-analyses and cohort studies, and relationships between this score and testosterone levels were tested in 142 men ages 19 to 82 years. Greater burden of preexisting conditions for severe COVID-19 disease was related to lower testosterone levels among men younger than 40 years of age. In older men, the decrease in testosterone that accompanies aging attenuated the effect of the clinical risk score on free testosterone levels. Given that older age itself is a predictor of COVID-19 disease severity, these results together suggest that the presence of preexisting conditions may confound the relationship between testosterone levels and COVID-19 disease outcomes in men. Future research examining relationships among testosterone and outcomes related to infectious and chronic diseases should consider potential confounds, such as the role of preexisting conditions.
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Effects of mild/asymptomatic COVID-19 on semen parameters and sex-related hormone levels in men: a systematic review and meta-analysis.
Che, BW, Chen, P, Yu, Y, Li, W, Huang, T, Zhang, WJ, Xu, SH, He, J, Liu, M, Tang, KF
Asian journal of andrology. 2023;25(3):382-388
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Various studies have shown that coronavirus disease 2019 (COVID-19) can cause more harm and a higher mortality rate to men. However, the literature does not clearly show that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause serious and lasting damage to male reproductive function. The aims of this study were to explore the effects of mild/asymptomatic COVID-19 on semen parameters and sex-related hormone levels and to analyse the relationship between semen parameter values and semen collection time after infection, fever, and severity of COVID-19. This study is a systematic review and meta-analysis of thirteen studies of which only five were included in the meta-analysis. Results show that COVID-19 has a certain effect on male reproductive function in the short term especially within about 70 days after infection. Additionally, fever after infection only had a significant effect on sperm concentration. Authors conclude by recommending the avoidance of pregnancy for a short period of time when the male partner has been infected with COVID-19.
Abstract
Coronavirus disease 2019 (COVID-19) has yet to be proven to alter male reproductive function, particularly in the majority of mild/asymptomatic patients. The purpose of this study was to explore whether mild/asymptomatic COVID-19 affects semen quality and sex-related hormone levels. To find suitable comparative studies, a systematic review and meta-analysis was done up to January 22, 2022, by using multiple databases (Web of Science, PubMed, and Embase). Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to identify and choose the studies. Meta-analysis was used to examine the semen parameters and sex-related hormones of mild/asymptomatic COVID-19 patients before and after infection. The effects of semen collection time, fever, and intensity of verification on semen following infection were also investigated. A total of 13 studies (n = 770) were included in the analysis, including three case-control studies, six pre-post studies, and four single-arm studies. A meta-analysis of five pre-post studies showed that after infection with COVID-19, sperm concentration (I2 = 0; P = 0.003), total sperm count (I2 = 46.3%; P = 0.043), progressive motility (I2 = 50.0%; P < 0.001), total sperm motility (I2 = 76.1%; P = 0.047), and normal sperm morphology (I2 = 0; P = 0.001) decreased. Simultaneously, a systematic review of 13 studies found a significant relationship between semen collection time after infection, inflammation severity, and semen parameter values, with fever having only bearing on semen concentration. Furthermore, there was no significant difference in sex-related hormone levels before and after infection in mild/asymptomatic patients. Mild/asymptomatic COVID-19 infection had a significant effect on semen quality in the short term. It is recommended to avoid initiating a pregnancy during this period of time.
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COVID-19-associated lung weakness (CALW): Systematic review and meta-analysis.
Redruello-Guerrero, P, Ruiz-Del-Pino, M, Jiménez-Gutiérrez, C, Jiménez-Gutiérrez, P, Carrascos-Cáliz, A, Romero-Linares, A, Láinez Ramos-Bossini, AJ, Rivera-Izquierdo, M, Cárdenas-Cruz, A
Medicina intensiva. 2023;47(10):583-593
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During the Covid-19 pandemic there was an increase in the number of individuals experiencing a collapsed lung, otherwise known as a pneumothorax (PNX) or pneumomediastinum (PNMD). The reasons for increased PNX are unclear and this systematic review and meta-analysis of 12 studies including 4901 individuals with Covid-19 aimed to determine what may be responsible for this. The results showed that 1629 individuals experienced a PNX and 253 a PNMD, and death was higher amongst those who developed PNX and PNMD. There were strong associations between the occurrence of PNX and PNMD and death. It was concluded that PNX and PNMD significantly increased the risk of dying in individuals with Covid-19 and it was proposed that the term Covid-19-Associated Lung Weakness (CALW) should be applied to those who experience PNX of PNMD. There was some concern that the quality of the research used was very low and so this study could be used by healthcare professionals to understand that PNX and PNMD in Covid-19 patients should be closely monitored and managed.
Abstract
OBJECTIVES To assess mortality and different clinical factors derived from the development of atraumatic pneumothorax (PNX) and/or pneumomediastinum (PNMD) in critically ill patients as a consequence of COVID-19-associated lung weakness (CALW). DESIGN Systematic review with meta-analysis. SETTING Intensive Care Unit (ICU). PARTICIPANTS Original research evaluating patients, with or without the need for protective invasive mechanical ventilation (IMV), with a diagnosis of COVID-19, who developed atraumatic PNX or PNMD on admission or during hospital stay. INTERVENTIONS Data of interest were obtained from each article and analyzed and assessed by the Newcastle-Ottawa Scale. The risk of the variables of interest was assessed with data derived from studies including patients who developed atraumatic PNX or PNMD. MAIN VARIABLES OF INTEREST Mortality, mean ICU stay and mean PaO2/FiO2 at diagnosis. RESULTS Information was collected from 12 longitudinal studies. Data from a total of 4901 patients were included in the meta-analysis. A total of 1629 patients had an episode of atraumatic PNX and 253 patients had an episode of atraumatic PNMD. Despite the finding of significantly strong associations, the great heterogeneity between studies implies that the interpretation of results should be made with caution. CONCLUSIONS Mortality among COVID-19 patients was higher in those who developed atraumatic PNX and/or PNMD compared to those who did not. The mean PaO2/FiO2 index was lower in patients who developed atraumatic PNX and/or PNMD. We propose grouping these cases under the term COVID-19-associated lung weakness (CALW). OBJETIVO Evaluar la mortalidad y diversos factores clínicos derivados del desarrollo de neumotórax (NTX) y/o neumomediastino (NMD) atraumáticos en pacientes críticos como consecuencia de la debilidad pulmonar asociada a COVID-19 (DPAC). DISEÑO: Revisión sistemática con metaanálisis. ÁMBITO Unidad de Cuidados Intensivos (UCI). PARTICIPANTES Investigaciones originales en las que se evaluase a pacientes, con o sin necesidad de ventilación mecánica invasiva (VMI), con diagnóstico de COVID-19 que hubiesen desarrollado NTX o NMD atraumáticos al ingreso o durante su estancia hospitalaria. INTERVENCIONES Se obtuvieron los datos de interés de cada artículo que fueron analizados y evaluados por la Escala Newcastle-Ottawa. El riesgo de las variables de interés principales se evaluó por los datos derivados de los estudios que incluyeron a pacientes que desarrollaron NTX o NMD atraumáticos. VARIABLES DE INTERÉS PRINCIPALS Mortalidad, estancia media en la UCI y PaO2/FiO2 media en el momento diagnóstico. RESULTADOS Se recogieron datos de 12 estudios longitudinales. En el metaanálisis se incluyeron datos de un total de 4.901 pacientes, entre los cuales 1.629 presentaron un episodio de NTX y 253 de NMD atraumáticos. A pesar de encontrar asociaciones significativamente fuertes, la alta heterogeneidad entre los estudios hace que la interpretación de los resultados deba hacerse con cautela. CONCLUSIONES La mortalidad de los pacientes COVID-19 fue mayor en los que desarrollaron NTX y/o NMD atraumáticos con respecto a los que no lo hicieron. La media del índice PaO2/FiO2 fue menor en los pacientes que desarrollaron NTX y/o NMD atraumáticos. Proponemos agrupar bajo el término deDPAC estos casos.
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Association between SARS-CoV-2 infection and disease severity among prostate cancer patients on androgen deprivation therapy: a systematic review and meta-analysis.
Sari Motlagh, R, Abufaraj, M, Karakiewicz, PI, Rajwa, P, Mori, K, Mun, DH, Shariat, SF
World journal of urology. 2022;40(4):907-914
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The incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is equal in both sexes; however, disease severity and progression rates are approximately three times higher in the male gender. Androgen deprivation therapy (ADT) and the second-generation androgen receptor targeting therapy were developed to suppress the androgen-activated intracellular cascade that leads to tumour progression and aggressive tumour growth. The aim of this study was to assess the risk of SARS-CoV-2 infection and the severity of disease in prostate cancer (PCa) patients treated with ADT. This study is a systematic review and meta-analysis of six cohort studies. The study results show that there is not a significant association between ADT use and the severity of SARS-CoV-2 infection or coronavirus disease 2019 (COVID-19) in PCa patients. However, results also show that ADT does not worsen COVID-19 risk and trajectory. Authors conclude that ADT, as a cancer treatment, might be safely administered to patients during the COVID-19 pandemic.
Abstract
PURPOSE Androgen-regulated enzymes such as the angiotensin-converting enzyme 2 (ACE2) and the transmembrane serine protease 2 (TMPRSS2) are involved in the SARS-CoV-2 infection process. The expression of TMPRSS2 and its fusion gene, which are increased in the epithelium of the human prostate gland during prostate carcinogenesis, are regulated by androgens. Our goal was to assess the risk of the SARS-CoV-2 infection and the severity of the disease in PCa patients treated with androgen deprivation therapy (ADT). METHODS We conducted a systematic review and meta-analysis according to PRISMA guidelines. We queried PubMed and Web of Science databases on 1 July 2021. We used random- and/or fixed-effects meta-analytic models in the presence or absence of heterogeneity according to Cochrane's Q test and I2 statistic, respectively. RESULTS Six retrospective studies (n = 50,220 patients) were selected after considering inclusion and exclusion criteria for qualitative evidence synthesis. Four retrospective studies were included to assess the SARS-CoV-2 infection risk in PCa patients under ADT vs. no ADT and the summarized risk ratio (RR) was 0.8 (95% confidence intervals (CI) 0.44-1.47). Five retrospective studies were included to assess the severity of coronavirus disease 2019 (COVID-19) in PCa patients under ADT versus no ADT and the summarized RR was 1.23 (95% CI 0.9-1.68). CONCLUSION We found a non-significant association between the risk of SARS-CoV-2 infection and COVID-19 severity in PCa patients treated with ADT. However, our results suggest that during the COVID-19 pandemic PCa patients can safely undergo ADT as a cancer therapy without worsening COVID-19 risk and trajectory.
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Efficacy of telemedicine for the management of cardiovascular disease: a systematic review and meta-analysis.
Kuan, PX, Chan, WK, Fern Ying, DK, Rahman, MAA, Peariasamy, KM, Lai, NM, Mills, NL, Anand, A
The Lancet. Digital health. 2022;4(9):e676-e691
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Digital health interventions (DHIs) have the potential to transform the diagnosis, monitoring, and management of chronic cardiovascular conditions. Many DHIs are widely deployed in health systems across the world, with adoption rapidly increasing in response to the coronavirus disease 2019 pandemic. The aim of this study was to provide an updated synthesis of evidence on the effectiveness of telemedicine in the management of cardiovascular diseases. This study is a systematic review and meta-analysis of seventy-two studies with a total of 127,869 participants, of whom 82,818 (65%) were males and 45051 (35%) were females. Results showed reduced cardiovascular-related mortality and hospitalisation for patients with heart failure who received combined remote telemedicine monitoring and consultation compared with usual care. Authors conclude that the findings of their study suggest a definite role for telemedicine in the management of heart failure, particularly in early treatment optimisation, but the value is less clear for long-term management strategy and other cardiovascular diseases. Thus, future research should focus to address the application of these technologies to unselected populations and longer-term effectiveness.
Abstract
BACKGROUND Telemedicine has been increasingly integrated into chronic disease management through remote patient monitoring and consultation, particularly during the COVID-19 pandemic. We did a systematic review and meta-analysis of studies reporting effectiveness of telemedicine interventions for the management of patients with cardiovascular conditions. METHODS In this systematic review and meta-analysis, we searched PubMed, Scopus, and Cochrane Library from database inception to Jan 18, 2021. We included randomised controlled trials and observational or cohort studies that evaluated the effects of a telemedicine intervention on cardiovascular outcomes for people either at risk (primary prevention) of cardiovascular disease or with established (secondary prevention) cardiovascular disease, and, for the meta-analysis, we included studies that evaluated the effects of a telemedicine intervention on cardiovascular outcomes and risk factors. We excluded studies if there was no clear telemedicine intervention described or if cardiovascular or risk factor outcomes were not clearly reported in relation to the intervention. Two reviewers independently assessed and extracted data from trials and observational and cohort studies using a standardised template. Our primary outcome was cardiovascular-related mortality. We evaluated study quality using Cochrane risk-of-bias and Newcastle-Ottawa scales. The systematic review and the meta-analysis protocol was registered with PROSPERO (CRD42021221010) and the Malaysian National Medical Research Register (NMRR-20-2471-57236). FINDINGS 72 studies, including 127 869 participants, met eligibility criteria, with 34 studies included in meta-analysis (n=13 269 with 6620 [50%] receiving telemedicine). Combined remote monitoring and consultation for patients with heart failure was associated with a reduced risk of cardiovascular-related mortality (risk ratio [RR] 0·83 [95% CI 0·70 to 0·99]; p=0·036) and hospitalisation for a cardiovascular cause (0·71 [0·58 to 0·87]; p=0·0002), mostly in studies with short-term follow-up. There was no effect of telemedicine on all-cause hospitalisation (1·02 [0·94 to 1·10]; p=0·71) or mortality (0·90 [0·77 to 1·06]; p=0·23) in these groups, and no benefits were observed with remote consultation in isolation. Small reductions were observed for systolic blood pressure (mean difference -3·59 [95% CI -5·35 to -1·83] mm Hg; p<0·0001) by remote monitoring and consultation in secondary prevention populations. Small reductions were also observed in body-mass index (mean difference -0·38 [-0·66 to -0·11] kg/m2; p=0·0064) by remote consultation in primary prevention settings. INTERPRETATION Telemedicine including both remote disease monitoring and consultation might reduce short-term cardiovascular-related hospitalisation and mortality risk among patients with heart failure. Future research should evaluate the sustained effects of telemedicine interventions. FUNDING The British Heart Foundation.
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Clinical applications of detecting IgG, IgM or IgA antibody for the diagnosis of COVID-19: A meta-analysis and systematic review.
Chen, M, Qin, R, Jiang, M, Yang, Z, Wen, W, Li, J
International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases. 2021;104:415-422
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The rapidly spreading nature of COVID-19 has put an emphasis on the importance of fast diagnosis. Gold standard diagnosis is through reverse transcription polymerase chain reaction (RT-PCR) tests, which aims to detect the presence of COVID-19. However, challenges with collection techniques and when in the disease lifecycle these tests are taken, can affect their reliability, highlighting a need for alternative methods of testing. Other testing methods exist, which involve testing the body’s own immune response to the presence of COVID-19, however these may also have their limitations. This systematic review and meta-analysis aimed to determine the effectiveness of testing the body’s own immune reaction for the presence of COVID-19. The results showed that testing the body’s immune reaction was effective, however if the person being tested is at an early stage in the disease, then it may be misdiagnosed. This study could be used by healthcare professionals to understand that the use of any type of COVID-19 testing may have its limitations, and although a person may test negative, there is still a possibility that they have the infection if symptoms exist
Abstract
BACKGROUND The coronavirus disease 2019 (COVID-19) pandemic has had a devastating impact worldwide, and timely detection and quarantine of infected patients are critical to prevent spread of disease. Serological antibody testing is an important diagnostic method used increasingly in clinics, although its clinical application is still under investigation. METHODS A meta-analysis was conducted to compare the diagnostic performance of severe acute respiratory syndrome coronavirus-2 antibody tests in patients with COVID-19. The test results analysed included: (1) IgM-positive but IgG-negative (IgM+IgG-); (2) IgG-positive but IgM-negative (IgG+IgM-); (3) both IgM-positive and IgG-positive (IgM+IgG+); (4) IgM-positive without IgG information (IgM+IgG+/-); (5) IgG-positive without IgM information (IgG+IgM+/-); (6) either IgM-positive or IgG-positive (IgM+ or IgG+); and (7) IgA-positive (IgA+). RESULTS Sixty-eight studies were included. Pooled sensitivities for IgM+IgG-, IgG+IgM-, IgM+IgG+, IgM+IgG+/-, IgG+IgM+/-, and IgM+ or IgG+ were 6%, 7%, 53%, 68%, 73% and 79% respectively. Pooled specificities ranged from 98% to 100%. IgA+ had a pooled sensitivity of 78% but a relatively low specificity of 88%. Tests conducted 2 weeks after symptom onset showed better diagnostic accuracy than tests conducted earlier. Chemiluminescence immunoassay and detection of S protein as the antigen could offer more accurate diagnostic results. DISCUSSION These findings support the supplemental role of serological antibody tests in the diagnosis of COVID-19. However, their capacity to diagnose COVID-19 early in the disease course could be limited.
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Case report and systematic review suggest that children may experience similar long-term effects to adults after clinical COVID-19.
Ludvigsson, JF
Acta paediatrica (Oslo, Norway : 1992). 2021;110(3):914-921
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The long-term effects of COVID-19 is becoming increasingly documented in adults. Symptoms such as fatigue, headache and depression have all been reported, however data on the possible long-term effects of COVID-19 in children is scarce. The aim of this systematic review and case report was to describe the long-term effects of COVID-19 in five children and support this with other reports in the literature. The results showed that of the five case reports of long COVID, four were girls aged 9-15 years. All subjects reported symptoms lasting between 6-8 months. Most common symptoms were fatigue, difficulty breathing and heart issues. The systematic literature review did not find any publications which documented long COVID in children. It was concluded that children may experience long COVID symptoms and girls may be more susceptible. This study could be used by healthcare professionals to understand that children may also be affected by long COVID and that patients should be monitored for symptoms for at least 6-8 months.
Abstract
AIM: Persistent symptoms in adults after COVID-19 are emerging and the term long COVID is increasingly appearing in the literature. However, paediatric data are scarce. METHODS This paper contains a case report of five Swedish children and the long-term symptoms reported by their parents. It also includes a systematic literature review of the MEDLINE, EMBASE and Web of Science databases and the medRxiv/bioRxiv pre-print servers up to 2 November 2020. RESULTS The five children with potential long COVID had a median age of 12 years (range 9-15) and four were girls. They had symptoms for 6-8 months after their clinical diagnoses of COVID-19. None were hospitalised at diagnosis, but one was later admitted for peri-myocarditis. All five children had fatigue, dyspnoea, heart palpitations or chest pain, and four had headaches, difficulties concentrating, muscle weakness, dizziness and sore throats. Some had improved after 6-8 months, but they all suffered from fatigue and none had fully returned to school. The systematic review identified 179 publications and 19 of these were deemed relevant and read in detail. None contained any information on long COVID in children. CONCLUSION Children may experience similar long COVID symptoms to adults and females may be more affected.
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COVID-19 and chronic fatigue syndrome: Is the worst yet to come?
Wostyn, P
Medical hypotheses. 2021;146:110469
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A proportion of COVID-19 patients develop post-COVID-19 syndrome, with long-term symptoms such as persistent fatigue, muscle pains, depressive symptoms, and non-restorative sleep, similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In this article the author presents his medical hypothesis that, in a subset of patients at least, post-COVID-19 fatigue syndrome may result from damage to olfactory (smell) sensory neurons, which in turn may lead to toxic build-up within the central nervous system (CNS) through congestion of the glymphatic system (the waste clearance system of the CNS). Loss of smell and altered sensation of taste have been reported in 33–80% of COVID-19 patients but the underlying mechanisms are not yet known. Most of these patients regain their sense of smell within 1-3 weeks, suggesting that the virus does not affect the olfactory neurons but their surrounding supporting cells. Some patients, however, do not regain their sense of smell for months which may point to the destruction of neurons. A decrease in olfactory neurons may affect the flow of the cerebrospinal fluid (CSF) in an area important for CSF drainage. This may cause an increase in intracranial pressure (idiopathic intracranial hypertension, IIH) and congestion of the glymphatic system, which have been associated with chronic fatigue syndrome, as well as with headaches and tinnitus, symptoms also commonly seen in COVID-19 patients. The author states that if this hypothesis is confirmed, glymphatic-lymphatic drainage therapies, such as osteopathy, should be recommended as early treatment for patients with post-COVID-19 fatigue syndrome.
Abstract
There has been concern about possible long-term sequelae resembling myalgic encephalomyelitis/chronic fatigue syndrome in COVID-19 patients. Clarifying the mechanisms underlying such a "post-COVID-19 fatigue syndrome" is essential for the development of preventive and early treatment methods for this syndrome. In the present paper, by integrating insights pertaining to the glymphatic system and the nasal cerebrospinal fluid outflow pathway with findings in patients with chronic fatigue syndrome, idiopathic intracranial hypertension, and COVID-19, I provide a coherent conceptual framework for understanding the pathophysiology of post-COVID-19 fatigue syndrome. According to this hypothesis, this syndrome may result from damage to olfactory sensory neurons, causing reduced outflow of cerebrospinal fluid through the cribriform plate, and further leading to congestion of the glymphatic system with subsequent toxic build-up within the central nervous system. I further postulate that patients with post-COVID-19 fatigue syndrome may benefit from cerebrospinal fluid drainage by restoring glymphatic transport and waste removal from the brain. Obviously, further research is required to provide further evidence for the presence of this post-viral syndrome, and to provide additional insight regarding the relative contribution of the glymphatic-lymphatic system to it. Other mechanisms may also be involved. If confirmed, the glymphatic-lymphatic system could represent a target in combating post-COVID-19 fatigue syndrome. Moreover, further research in this area could also provide new insights into the understanding of chronic fatigue syndrome.
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Systemic Perturbations in Amine and Kynurenine Metabolism Associated with Acute SARS-CoV-2 Infection and Inflammatory Cytokine Responses.
Lawler, NG, Gray, N, Kimhofer, T, Boughton, B, Gay, M, Yang, R, Morillon, AC, Chin, ST, Ryan, M, Begum, S, et al
Journal of proteome research. 2021;20(5):2796-2811
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Understanding the action of Covid-19 and the host response is paramount to developing personalised treatments and improving recovery rates. This cohort study of 64 individuals aimed to determine underlying biological signatures of individuals with severe and mild Covid-19, to potentially risk stratify patients and provide targeted treatments. The results showed that several biological signatures were disrupted with infection, some increased and some decreased and indicated possible liver, brain, and inflammatory disruptions. There was also evidence of a time-based pattern of biological disruptions, which may be of significance when looking at “long Covid” syndrome. It was concluded that identifying the hosts biological response to the virus offers insights into the viral action on the body. The action of Covid-19 on processes in the brain may indicate a secondary effect of the virus. Using biological markers to predict recovery of individuals suffering from “long Covid” may also be a possibility. This study could be used by healthcare professionals to understand which biological processes may be disrupted during Covid-19 infection, with the view to testing to understand who may be at risk of long-term complications post recovery.
Abstract
We performed quantitative metabolic phenotyping of blood plasma in parallel with cytokine/chemokine analysis from participants who were either SARS-CoV-2 (+) (n = 10) or SARS-CoV-2 (-) (n = 49). SARS-CoV-2 positivity was associated with a unique metabolic phenotype and demonstrated a complex systemic response to infection, including severe perturbations in amino acid and kynurenine metabolic pathways. Nine metabolites were elevated in plasma and strongly associated with infection (quinolinic acid, glutamic acid, nicotinic acid, aspartic acid, neopterin, kynurenine, phenylalanine, 3-hydroxykynurenine, and taurine; p < 0.05), while four metabolites were lower in infection (tryptophan, histidine, indole-3-acetic acid, and citrulline; p < 0.05). This signature supports a systemic metabolic phenoconversion following infection, indicating possible neurotoxicity and neurological disruption (elevations of 3-hydroxykynurenine and quinolinic acid) and liver dysfunction (reduction in Fischer's ratio and elevation of taurine). Finally, we report correlations between the key metabolite changes observed in the disease with concentrations of proinflammatory cytokines and chemokines showing strong immunometabolic disorder in response to SARS-CoV-2 infection.