Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
1.
Int J Infect Dis ; 130: 60-70, 2023 May.
Artículo en Inglés | MEDLINE | ID: covidwho-2265428

RESUMEN

OBJECTIVES: Asymptomatic infections and mild diseases were more common during the Omicron outbreak in Shanghai, China in 2022. This study aimed to assess the characteristics and viral RNA decay between patients with asymptomatic and mild infections. METHODS: A total of 55,111 patients infected with SARS-CoV-2 who were quarantined in the National Exhibition & Convention Center (Shanghai) Fangcang shelter hospital within 3 days after diagnosis from April 9 to May 23, 2022 were enrolled. The kinetics of cycle threshold (Ct) values of reverse transcription-polymerase chain reaction were assessed. The influencing factors for disease progression and the risk factors for the viral RNA shedding time (VST) were investigated. RESULTS: On admission, 79.6% (43,852/55,111) of the cases were diagnosed with asymptomatic infections, and 20.4% were mild diseases. However, 78.0% of initially asymptomatic subjects developed mild diseases at the follow-up. The final proportion of asymptomatic infections was 17.5%. The median time of symptom onset, the duration of symptoms, and the VST were 2 days, 5 days, and 7 days, respectively. Female, age 19-40 years, underlying comorbidities with hypertension and diabetes, and vaccination were associated with higher risks of progressing to mildly symptomatic infections. In addition, mildly symptomatic infections were found to be associated with prolonged VST compared with asymptomatic infections. However, the kinetics of viral RNA decay and dynamics of Ct values were similar among asymptomatic subjects, patients with asymptomatic-to-mild infection, and patients with mild infection. CONCLUSION: A large proportion of initially diagnosed asymptomatic Omicron infections is in the presymptomatic stage. The Omicron infection has a much shorter incubation period and VST than previous variants. The infectivity of asymptomatic infections and mildly symptomatic infections with Omicron is similar.


Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , Femenino , Adulto Joven , Adulto , SARS-CoV-2/genética , COVID-19/diagnóstico , COVID-19/epidemiología , ARN Viral/genética , Infecciones Asintomáticas/epidemiología , Estudios Retrospectivos , Hospitales Especializados , China/epidemiología , Unidades Móviles de Salud
2.
Int Immunopharmacol ; 114: 109534, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: covidwho-2131204

RESUMEN

BACKGROUND: Viral persistence is a crucial factor that influences the transmissibility of SARS-CoV-2. However, the impacts of vaccination and physiological variables on viral persistence have not been adequately clarified. METHODS: We collected the clinical records of 377 COVID-19 patients, which contained unvaccinated patients and patients received two doses of an inactivated vaccine or an mRNA vaccine. The impacts of vaccination on disease severity and viral persistence and the correlations between 49 laboratory variables and viral persistence were analyzed separately. Finally, we established a multivariate regression model to predict the persistence of viral RNA. RESULTS: Both inactivated and mRNA vaccines significantly reduced the rate of moderate cases, while the vaccine related shortening of viral RNA persistence was only observed in moderate patients. Correlation analysis showed that 10 significant laboratory variables were shared by the unvaccinated mild patients and mild patients inoculated with an inactivated vaccine, but not by the mild patients inoculated with an mRNA vaccine. A multivariate regression model established based on the variables correlating with viral persistence in unvaccinated mild patients could predict the persistence of viral RNA for all patients except three moderate patients inoculated with an mRNA vaccine. CONCLUSION: Vaccination contributed limitedly to the clearance of viral RNA in COVID-19 patients. While, laboratory variables in early infection could predict the persistence of viral RNA.


Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , COVID-19/prevención & control , Estudios de Cohortes , Estudios Retrospectivos , ARN Viral , Vacunación , Anticuerpos Antivirales
3.
BMC Infect Dis ; 22(1): 831, 2022 Nov 09.
Artículo en Inglés | MEDLINE | ID: covidwho-2118050

RESUMEN

BACKGROUND: At present, the role of inactivated vaccines in viral RNA shedding among Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) breakthrough infections is still unknown. METHODS: We collected data of 147 coronavirus disease 2019 (COVID-19) patients with mild-to-moderate illness who were hospitalized in the Third People's Hospital of Yangzhou from 7 to 20 August 2021 and analyzed the differences in symptoms and laboratory tests among fully vaccinated (FV), partially vaccinated (PV) and unvaccinated (UV) patients. RESULTS: The median duration of viral RNA shedding was shorter in the FV (12 [IQR, 9.5-14] days) and PV (13 [IQR, 9-16.75] days) groups than in the UV group (15 [IQR, 11.75-17.25] days) (adjusted P < 0.001 and adjusted P = 0.23, respectively). The median titers of SARS-CoV-2-specific IgG and IgM were significantly higher in the FV (12.29 S/co [IQR, 2.08-63.59] and 0.3 S/co [IQR, 0.05-2.29], respectively) and PV (0.68 S/co [IQR, 0.14-28.69] and 0.12 S/co [0.03-5.23], respectively) groups than in the UV group (0.06 S/co [IQR, 0.03-0.47] and 0.04 S/co [IQR, 0.02-0.07]) (adjusted P < 0.001 and adjusted P = 0.008, respectively). CONCLUSIONS: Inactivated vaccines may shorten viral RNA shedding in breakthrough infected patients who have mild-to-moderate illness and may improve the ability of the host to generate specific antibodies to infection.


Asunto(s)
COVID-19 , Humanos , COVID-19/prevención & control , SARS-CoV-2 , ARN Viral , Estudios Retrospectivos , Vacunas de Productos Inactivados , Anticuerpos Antivirales , Inmunoglobulina G , Inmunoglobulina M
4.
J Med Virol ; 94(7): 3133-3137, 2022 07.
Artículo en Inglés | MEDLINE | ID: covidwho-1739184

RESUMEN

Clinicians are facing several challenges in tackling coronavirus disease 2019 (COVID-19); one issue is prolonged detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. Here, we describe a case of SARS-CoV-2 infection in a young immunocompetent patient with a virological course lasting for 71 days. Following antiviral treatment, but no additional glucocorticoid or interferon therapy, the patient recovered from COVID-19 pneumonia (moderate). Detection of viral RNA via throat swabs showed negative results. However, the viral RNA reappeared and persisted in stool samples for an additional 27 days, while the patient remained asymptomatic and exhibited no abnormal signs. This case indicates that SARS-CoV-2 can result in a prolonged fecal RNA shedding, even in an immunocompetent patient with zero exposure to immunosuppressive therapies.


Asunto(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnóstico , Heces , Humanos , ARN Viral/genética , Esparcimiento de Virus
5.
J Clin Lab Anal ; 35(11): e24002, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: covidwho-1525446

RESUMEN

BACKGROUND: The coronavirus disease 2019 (COVID-19) epidemic is still spreading rapidly around the world. Recent cases with prolonged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection have been successively reported, and the phenomenon of false-negative real-time polymerase chain reaction (RT-PCR) results of SARS-CoV-2 RNA or "repositive" was also described in COVID-19 patients. METHODS: We report a 69-year-old female patient with hypertension, suspected lung tumor, and previous history of total hysterectomy for hysteromyoma who presented with moderate COVID-19 symptoms and was positive for SARS-CoV-2 RNA by RT-PCR when she traveled from the USA to China. RESULTS: The patient required second and third re-hospitalizations due to "repositive" SARS-CoV-2 throat swab test results during post-charge solitary isolation and observation, and serum SARS-CoV-2-IgG decayed rapidly before disappearing on illness Day 139 when the throat swab was still positive. The virus shedding lasted for at least 146 days (the last positive throat swab test result was on illness Day 146, and the first true-negative test result was on illness Day 151) since her initial positive test. CONCLUSION: Prolonged SARS-CoV-2 RNA viral shedding is prone to occur in an immunocompromised host, wherein changes in the host immune status can lead to repeated positive SARS-CoV-2 detection. Moreover, the SARS-CoV-2-IgG may decrease rapidly and disappear before virus removal, indicating there may be certain limitations on the protective effect of the SARS-CoV-2 antibody, which deserves clinical attention.


Asunto(s)
Anticuerpos Antivirales/sangre , COVID-19/virología , Inmunoglobulina G/sangre , SARS-CoV-2/inmunología , Esparcimiento de Virus , Anciano , COVID-19/inmunología , Femenino , Humanos , ARN Viral/análisis , SARS-CoV-2/aislamiento & purificación
6.
Viruses ; 13(3)2021 03 19.
Artículo en Inglés | MEDLINE | ID: covidwho-1143617

RESUMEN

The heterogeneity of immune response to COVID-19 has been reported to correlate with disease severity and prognosis. While so, how the immune response progress along the period of viral RNA-shedding (VRS), which determines the infectiousness of disease, is yet to be elucidated. We aim to exhaustively evaluate the peripheral immune cells to expose the interplay of the immune system in uncomplicated COVID-19 cases with different VRS periods and dynamic changes of the immune cell profile in the prolonged cases. We prospectively recruited four uncomplicated COVID-19 patients and four healthy controls (HCs) and evaluated the immune cell profile throughout the disease course. Peripheral blood mononuclear cells (PBMCs) were collected and submitted to a multi-panel flowcytometric assay. CD19+-B cells were upregulated, while CD4, CD8, and NK cells were downregulated in prolonged VRS patients. Additionally, the pro-inflammatory-Th1 population showed downregulation, followed by improvement along the disease course, while the immunoregulatory cells showed upregulation with subsequent decline. COVID-19 patients with longer VRS expressed an immune profile comparable to those with severe disease, although they remained clinically stable. Further studies of immune signature in a larger cohort are warranted.


Asunto(s)
Linfocitos B/inmunología , COVID-19/inmunología , COVID-19/virología , Leucocitos Mononucleares/inmunología , ARN Viral/metabolismo , SARS-CoV-2/fisiología , Linfocitos T/inmunología , Esparcimiento de Virus , Femenino , Humanos , Masculino , Persona de Mediana Edad , ARN Viral/genética , SARS-CoV-2/genética , Adulto Joven
7.
Front Med (Lausanne) ; 7: 562875, 2020.
Artículo en Inglés | MEDLINE | ID: covidwho-874495

RESUMEN

An outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become pandemic worldwide. A better understanding of asymptomatic infections is crucial to prevent and control this epidemic. Here, we report the epidemiological and clinical characteristics of a family cluster with SARS-CoV-2 infection. In the family cluster, a 32-year-old male (case 1) and a 53-year-old female (case 2, the mother-in-law of case 1) exhibited clinical symptoms of COVID-19, while case 1's 32-year-old wife (case 3) and their 11-month-old daughter (case 4) were both asymptomatic. Notably, case 4's nasopharyngeal swab samples was negative for nearly 80 days, and her immune system has been boosted for at least 57 days, but the fecal samples have tested positive for 100 days (May 13, 2020), suggesting SARS-CoV-2 may invade enterocytes and may exist in individuals with low antiviral immunity for a long term. This report highlights that asymptomatic infections should be managed with caution and vigilance. For SARS-CoV-2 testing of asymptomatic cases, besides the normally used nasopharyngeal swab, fecal sample testing is also needed.

8.
Clin Immunol ; 221: 108611, 2020 12.
Artículo en Inglés | MEDLINE | ID: covidwho-856558

RESUMEN

Since December 2019, Coronavirus Disease 2019 (COVID-19) has emerged as a global pandemic. We aimed to investigate the clinical characteristics and analyzed the risk factors for prolonged viral RNA shedding. We retrospectively collected data from 112 hospitalized COVID-19 patients in a single center in Wuhan, China. Factors associated with prolonged viral RNA shedding (≥28 days) were investigated. Forty-nine (43.8%) patients had prolonged viral RNA shedding. Patients with prolonged viral shedding were older and had a higher rate of hypertension. Proinflammatory cytokines, including interleukin-2R (IL-2R) and tumor necrosis factor-α (TNF-α), were significantly elevated in patients with prolonged viral shedding. Multivariate analysis revealed that hypertension, older age, lymphopenia and elevated serum IL-2R were independent risk factors for prolonged viral shedding. This comprehensive investigation revealed the distinct characteristics between patients with or without prolonged viral RNA shedding. Hypertension, older age, lymphopenia and high levels of proinflammatory cytokines may be correlated with prolonged viral shedding.


Asunto(s)
COVID-19/virología , Síndrome de Liberación de Citoquinas/virología , Diabetes Mellitus/virología , Hipertensión/virología , Linfopenia/virología , ARN Viral/sangre , SARS-CoV-2/patogenicidad , Corticoesteroides/uso terapéutico , Adulto , Anciano , Anciano de 80 o más Años , COVID-19/diagnóstico , COVID-19/inmunología , China , Comorbilidad , Síndrome de Liberación de Citoquinas/diagnóstico , Síndrome de Liberación de Citoquinas/tratamiento farmacológico , Síndrome de Liberación de Citoquinas/inmunología , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/tratamiento farmacológico , Diabetes Mellitus/inmunología , Combinación de Medicamentos , Femenino , Hospitalización , Humanos , Hidroxicloroquina/uso terapéutico , Hipertensión/diagnóstico , Hipertensión/tratamiento farmacológico , Hipertensión/inmunología , Interferones/uso terapéutico , Lopinavir/uso terapéutico , Linfopenia/diagnóstico , Linfopenia/tratamiento farmacológico , Linfopenia/inmunología , Masculino , Persona de Mediana Edad , Receptores de Interleucina-2/biosíntesis , Estudios Retrospectivos , Factores de Riesgo , Ritonavir/uso terapéutico , Índice de Severidad de la Enfermedad , Factor de Necrosis Tumoral alfa/biosíntesis , Esparcimiento de Virus , Tratamiento Farmacológico de COVID-19
9.
Open Forum Infect Dis ; 7(8): ofaa331, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: covidwho-696111

RESUMEN

BACKGROUND: Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can shed virus, thereby causing human-to-human transmission, and the viral RNA shedding is commonly used as a proxy measure for infectivity. METHODS: We retrospectively reviewed confirmed cases of COVID-19 who attended the fever clinic of Wuhan Union Hospital from January 14 to February 24. In terms of the viral RNA shedding (median values) at first visit, patients were divided into a high-viral RNA shedding group and a low-viral RNA shedding group. Univariate and multivariate logistic regression analysis were performed to investigate the correlation between viral RNA shedding and clinical features. RESULTS: A total of 918 consecutive COVID-19 patients were enrolled, and severe patients made up 26.1%. After univariate and multivariate logistic regression, advanced age (odds ratio [OR], 1.02; 95% CI, 1.01-1.03; P = .001), having severe chronic diseases (OR, 1.44; 95% CI, 1.03-2.01; P = .04), and severe illness (OR, 1.60; 95% CI, 1.12-2.28; P = .01) were independent risk factors for high viral RNA shedding. Shorter time interval from symptom onset to viral detection was a protective factor for viral RNA shedding (OR, 0.97; 95% CI, 0.94-0.99; P = .01). Compared with mild patients, severe patients have higher virus shedding over a long period of time after symptom onset (P = .01). CONCLUSIONS: Outpatients who were old, had severe illness, and had severe underlying diseases had high viral RNA shedding.

10.
J Clin Virol ; 130: 104577, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: covidwho-693827

RESUMEN

BACKGROUND: Molecular detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is key in the diagnosis of coronavirus disease 2019 (COVID-19) and has been widely used for followup of cases as a proxy for contagiousness. The persistence of SARS-CoV-2 RNA shedding in the context of clinical features and comorbidities is understudied. METHODS: We retrospectively reviewed laboratory-confirmed COVID-19 adult symptomatic cases at Mayo Clinic, eventually achieving cessation of viral RNA shedding (CVS), defined as two consecutive negative SARS-CoV-2 PCR results on nasopharyngeal swabs collected at least 24 h apart. RESULTS: A total of 251 patients were included, median age was 53 years and 59 % female. The most common symptoms at diagnosis were cough, myalgia, dyspnea, fever and chills. Myalgia, cough, anosmia, ageusia and sore throat were common at CVS, but fever and dyspnea were not observed. The median time from symptom onset to CVS was 23 days, and did not differ by symptoms. The weekly cumulative CVS rate was 2, 14, 44, 73, 91 and 95 % at 1-6 weeks from symptom onset, respectively. Cough and fever were associated with a positive PCR test if tested within 2 weeks of symptoms (P < 0.05). Patients with asthma or immunosuppression were less likely to achieve CVS if tested 3 weeks into symptoms (P < 0.04). CONCLUSIONS: The cumulative CVS rate at 3 weeks from symptom-onset is 44 % in our entire cohort. The findings of our study highlight the low yield of repeating a SARS-CoV-2 NP PCR test within 21 days of a laboratoryconfirmed COVID-19 diagnosis.


Asunto(s)
Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/virología , Neumonía Viral/diagnóstico , Neumonía Viral/virología , ARN Viral/análisis , Esparcimiento de Virus , Adulto , Anciano , Betacoronavirus , COVID-19 , Prueba de COVID-19 , Técnicas de Laboratorio Clínico , Comorbilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Técnicas de Diagnóstico Molecular , Nasofaringe/virología , Pandemias , Estudios Retrospectivos , SARS-CoV-2 , Adulto Joven
11.
J Pediatric Infect Dis Soc ; 9(3): 366-369, 2020 Jul 13.
Artículo en Inglés | MEDLINE | ID: covidwho-681735

RESUMEN

We evaluated severe acute respiratory syndrome coronavirus 2 RNA clearance in 22 children. The estimation of positivity at day 14 was 52% for nasopharyngeal swab and 31% for stool samples. These data underline the significance of nasopharyngeal and stoolsample for detecting infected children. Additional studies are needed for transmissibility.


Asunto(s)
Betacoronavirus , Infecciones por Coronavirus/virología , Neumonía Viral/virología , Esparcimiento de Virus , COVID-19 , Niño , Preescolar , Infecciones por Coronavirus/transmisión , Heces/virología , Femenino , Humanos , Lactante , Recién Nacido , Italia/epidemiología , Masculino , Nasofaringe/virología , Pandemias , Neumonía Viral/transmisión , ARN Viral/metabolismo , SARS-CoV-2 , Factores de Tiempo
12.
Clin Transl Immunology ; 9(7): e1160, 2020.
Artículo en Inglés | MEDLINE | ID: covidwho-679726

RESUMEN

OBJECTIVES: A wide range of duration of viral RNA shedding in patients infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been observed. We aimed to investigate factors associated with prolonged and intermittent viral RNA shedding in a retrospective cohort of symptomatic COVID-19 patients. METHODS: Demographic, clinical and laboratory data from hospitalised COVID-19 patients from a single centre with two consecutive negative respiratory reverse transcription-polymerase chain reaction (RT-PCR) results were extracted from electronic medical records. Kaplan-Meier survival curve analysis was used to assess the effect of clinical characteristics on the duration and pattern of shedding. Plasma levels of immune mediators were measured using Luminex multiplex microbead-based immunoassay. RESULTS: There were 201 symptomatic patients included. Median age was 49 years (interquartile range 16-61), and 52.2% were male. Median RNA shedding was 14 days (IQR 9-18). Intermittent shedding was observed in 77 (38.3%). We did not identify any factor associated with prolonged or intermittent viral RNA shedding. Duration of shedding was inversely correlated with plasma levels of T-cell cytokines IL-1ß and IL-17A at the initial phase of infection, and patients had lower levels of pro-inflammatory cytokines during intermittent shedding. CONCLUSIONS: Less active T-cell responses at the initial phase of infection were associated with prolonged viral RNA shedding, suggesting that early immune responses are beneficial to control viral load and prevent viral RNA shedding. Intermittent shedding is common and may explain re-detection of viral RNA in recovered patients.

13.
Int J Infect Dis ; 98: 252-260, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: covidwho-621963

RESUMEN

OBJECTIVE: The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has become a global pandemic, but the factors influencing viral RNA shedding, which would help inform optimal control strategies, remain unclear. METHODS: The clinical course and viral RNA shedding pattern of 267 consecutive symptomatic COVID-19 patients admitted to the hospital from January 20, 2020 to March 15, 2020 were evaluated retrospectively. RESULTS: The median duration of viral RNA shedding was 12 days (interquartile range 8-16 days) after the onset of illness. Of the 267 patients included in this study, 65.2% had viral RNA clearance within 14 days, 88.8% within 21 days, and 94.4% within 28 days. Older age (hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.98-1.00; p = 0.04), time lag from illness onset to hospital admission (HR 0.91, 95% CI 0.88-0.94; p < 0.001), diarrhea (HR 0.59, 95% CI 0.36-0.96; p = 0.036), corticosteroid treatment (HR 0.60, 95% CI 0.39-0.94; p = 0.024), and lopinavir/ritonavir use (HR 0.70, 95% CI 0.52-0.94; p = 0.014) were significantly and independently associated with prolonged viral RNA shedding. CONCLUSIONS: Early detection and timely hospital admission may be warranted for symptomatic COVID-19 patients, especially for older patients and patients with diarrhea. Corticosteroid treatment is associated with prolonged viral RNA shedding and should be used with caution. Lopinavir/ritonavir use may be associated with prolonged viral RNA shedding in non-severe patients; further randomized controlled trials are needed to confirm this finding.


Asunto(s)
Betacoronavirus/genética , Infecciones por Coronavirus/virología , Neumonía Viral/virología , ARN Viral/genética , Esparcimiento de Virus , Adulto , Anciano , Betacoronavirus/aislamiento & purificación , Betacoronavirus/fisiología , COVID-19 , Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/tratamiento farmacológico , Femenino , Hospitalización , Humanos , Lopinavir/uso terapéutico , Masculino , Persona de Mediana Edad , Pandemias , Neumonía Viral/diagnóstico , Neumonía Viral/tratamiento farmacológico , ARN Viral/metabolismo , Estudios Retrospectivos , Ritonavir/uso terapéutico , SARS-CoV-2 , Esparcimiento de Virus/efectos de los fármacos
14.
J Infect Dis ; 222(3): 367-371, 2020 07 06.
Artículo en Inglés | MEDLINE | ID: covidwho-436918

RESUMEN

The viral RNA shedding time (VST) for severe acute respiratory syndrome coronavirus 2 has not been well characterized. Clinical data were collected and compared between patients with short and long VSTs (in the lower and upper quartiles, respectively). The probability of recurrent positive reverse-transcription polymerase chain reaction results decreased sharply to 4.8% after 3 consecutive negative results. A series of ≥3 consecutive negative results was suitable as a criterion for the end of viral RNA shedding. The VST for shedding from the respiratory tract was significantly shorter in patients with normal B-cell counts on admission than in those with decreased B-cell counts (median [interquartile range], 11 [9-13] vs 16 [12-20] days, respectively; P = .001).


Asunto(s)
Linfocitos B/fisiología , Betacoronavirus/genética , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/virología , Neumonía Viral/inmunología , Neumonía Viral/virología , Sistema Respiratorio/virología , Esparcimiento de Virus , Betacoronavirus/inmunología , COVID-19 , Estudios de Casos y Controles , China , Citocinas/metabolismo , Femenino , Humanos , Modelos Logísticos , Recuento de Linfocitos , Masculino , Persona de Mediana Edad , Pandemias , Modelos de Riesgos Proporcionales , ARN Viral/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Estudios Retrospectivos , Factores de Riesgo , SARS-CoV-2 , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA