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2.
PLoS One ; 16(11): e0259908, 2021.
Article in English | MEDLINE | ID: covidwho-1705817

ABSTRACT

INTRODUCTION: The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in the Belgian community is mainly estimated based on test results of patients with coronavirus disease (COVID-19)-like symptoms. The aim of this study was to investigate the evolution of the SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) positivity ratio and distribution of viral loads within a cohort of asymptomatic patients screened prior hospitalization or surgery, stratified by age category. MATERIALS/METHODS: We retrospectively studied data on SARS-CoV-2 real-time RT-PCR detection in respiratory tract samples of asymptomatic patients screened pre-hospitalization or pre-surgery in nine Belgian hospitals located in Flanders over a 12-month period (1 April 2020-31 March 2021). RESULTS: In total, 255925 SARS-CoV-2 RT-PCR test results and 2421 positive results for which a viral load was reported, were included in this study. An unweighted overall SARS-CoV-2 real-time RT-PCR positivity ratio of 1.27% was observed with strong spatiotemporal differences. SARS-CoV-2 circulated predominantly in 80+ year old individuals across all time periods except between the first and second COVID-19 wave and in 20-30 year old individuals before the second COVID-19 wave. In contrast to the first wave, a significantly higher positivity ratio was observed for the 20-40 age group in addition to the 80+ age group compared to the other age groups during the second wave. The median viral load follows a similar temporal evolution as the positivity rate with an increase ahead of the second wave and highest viral loads observed for 80+ year old individuals. CONCLUSION: There was a high SARS-CoV-2 circulation among asymptomatic patients with a predominance and highest viral loads observed in the elderly. Moreover, ahead of the second COVID-19 wave an increase in median viral load was noted with the highest overall positivity ratio observed in 20-30 year old individuals, indicating they could have been the hidden drivers of this wave.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19/diagnosis , Respiratory Tract Infections/epidemiology , SARS-CoV-2/isolation & purification , Adolescent , Adult , Aged , Aged, 80 and over , Belgium/epidemiology , COVID-19/epidemiology , COVID-19/pathology , COVID-19/virology , Female , Hospitalization , Humans , Male , Middle Aged , Respiratory Tract Infections/pathology , Respiratory Tract Infections/surgery , Respiratory Tract Infections/virology , SARS-CoV-2/pathogenicity , Young Adult
3.
Sci Rep ; 11(1): 22892, 2021 11 24.
Article in English | MEDLINE | ID: covidwho-1532105

ABSTRACT

Clinical and prognostic differences between symptomatic and asymptomatic older patients with COVID-19 are of great interest since frail patients often show atypical presentation of illness. Lung Ultrasound (LUS) has been proven to be a reliable tool for detecting early-phase COVID-19 pneumonic alterations. The current prospective bicentric study aimed to compare LUS score and 3-month overall mortality between asymptomatic and symptomatic older patients with COVID-19, according to frailty status. Patients were stratified according to LUS score tertiles and Clinical Frailty Scale categories. Survival rate was assessed by telephone interviews 3 months after discharge. 64 symptomatic (24 women, aged 80.0 ± 10.8 years) and 46 asymptomatic (31 women, aged 84.3 ± 8.8 years) were consecutively enrolled. LUS score resulted an independent predictor of 3-month mortality [OR 2.27 (CI95% 1.09-4.8), p = 0.03], and the highest mortality rate was observed in symptomatic and asymptomatic pre-frail and frail patients (70.6% and 66.7%, respectively) with greater LUS abnormalities (3rd tertile). In conclusion, LUS identified an acute interstitial lung involvement in most of the older asymptomatic patients. Mortality rate progressively increased according to clinical frailty and LUS score degree, resulting a reliable prognostic tool in both symptomatic and asymptomatic patients.


Subject(s)
COVID-19/diagnostic imaging , COVID-19/mortality , Pneumonia/diagnostic imaging , Aged , Aged, 80 and over , Asymptomatic Diseases/epidemiology , COVID-19/complications , Female , Hospitalization , Humans , Lung/diagnostic imaging , Lung/pathology , Male , Pneumonia/immunology , Prognosis , Prospective Studies , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Tomography, X-Ray Computed/methods , Ultrasonography/methods
4.
PLoS One ; 16(11): e0259908, 2021.
Article in English | MEDLINE | ID: covidwho-1511834

ABSTRACT

INTRODUCTION: The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in the Belgian community is mainly estimated based on test results of patients with coronavirus disease (COVID-19)-like symptoms. The aim of this study was to investigate the evolution of the SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) positivity ratio and distribution of viral loads within a cohort of asymptomatic patients screened prior hospitalization or surgery, stratified by age category. MATERIALS/METHODS: We retrospectively studied data on SARS-CoV-2 real-time RT-PCR detection in respiratory tract samples of asymptomatic patients screened pre-hospitalization or pre-surgery in nine Belgian hospitals located in Flanders over a 12-month period (1 April 2020-31 March 2021). RESULTS: In total, 255925 SARS-CoV-2 RT-PCR test results and 2421 positive results for which a viral load was reported, were included in this study. An unweighted overall SARS-CoV-2 real-time RT-PCR positivity ratio of 1.27% was observed with strong spatiotemporal differences. SARS-CoV-2 circulated predominantly in 80+ year old individuals across all time periods except between the first and second COVID-19 wave and in 20-30 year old individuals before the second COVID-19 wave. In contrast to the first wave, a significantly higher positivity ratio was observed for the 20-40 age group in addition to the 80+ age group compared to the other age groups during the second wave. The median viral load follows a similar temporal evolution as the positivity rate with an increase ahead of the second wave and highest viral loads observed for 80+ year old individuals. CONCLUSION: There was a high SARS-CoV-2 circulation among asymptomatic patients with a predominance and highest viral loads observed in the elderly. Moreover, ahead of the second COVID-19 wave an increase in median viral load was noted with the highest overall positivity ratio observed in 20-30 year old individuals, indicating they could have been the hidden drivers of this wave.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19/diagnosis , Respiratory Tract Infections/epidemiology , SARS-CoV-2/isolation & purification , Adolescent , Adult , Aged , Aged, 80 and over , Belgium/epidemiology , COVID-19/epidemiology , COVID-19/pathology , COVID-19/virology , Female , Hospitalization , Humans , Male , Middle Aged , Respiratory Tract Infections/pathology , Respiratory Tract Infections/surgery , Respiratory Tract Infections/virology , SARS-CoV-2/pathogenicity , Young Adult
6.
Sci Rep ; 11(1): 19744, 2021 10 05.
Article in English | MEDLINE | ID: covidwho-1454810

ABSTRACT

Infections produced by non-symptomatic (pre-symptomatic and asymptomatic) individuals have been identified as major drivers of COVID-19 transmission. Non-symptomatic individuals, unaware of the infection risk they pose to others, may perceive themselves-and be perceived by others-as not presenting a risk of infection. Yet, many epidemiological models currently in use do not include a behavioral component, and do not address the potential consequences of risk misperception. To study the impact of behavioral adaptations to the perceived infection risk, we use a mathematical model that incorporates the behavioral decisions of individuals, based on a projection of the system's future state over a finite planning horizon. We found that individuals' risk misperception in the presence of non-symptomatic individuals may increase or reduce the final epidemic size. Moreover, under behavioral response the impact of non-symptomatic infections is modulated by symptomatic individuals' behavior. Finally, we found that there is an optimal planning horizon that minimizes the final epidemic size.


Subject(s)
Asymptomatic Diseases/psychology , Behavior , COVID-19/epidemiology , Asymptomatic Diseases/epidemiology , COVID-19/pathology , COVID-19/virology , Humans , Models, Theoretical , Perception , SARS-CoV-2/isolation & purification
7.
J Pediatr ; 239: 74-80.e1, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1433570

ABSTRACT

OBJECTIVES: To assess rates of asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) positivity in K-8 schools with risk mitigation procedures in place, and to evaluate SARS-CoV-2 transmission in school and household contacts of these positive individuals. STUDY DESIGN: In this prospective observational study, screening testing for SARS-CoV-2 was performed by oropharyngeal swabbing and polymerase chain reaction (PCR) analysis in students and staff at K-8 private schools in high-risk Chicago ZIP codes. New coronavirus disease 2019 (COVID-19) diagnoses or symptoms among participants, household contacts, and nonparticipants in each school were queried. RESULTS: Among 11 K-8 private schools across 8 Chicago ZIP codes, 468 participants (346 students, 122 staff members) underwent screening testing. At the first school, 17 participants (36%) tested positive, but epidemiologic investigation suggested against in-school transmission. Only 5 participants in the subsequent 10 schools tested positive for an overall 4.7% positivity rate (1.2% excluding school 1). All but 1 positive test among in-person students had high PCR cycle threshold values, suggesting very low SARS-CoV-2 viral loads. In all schools, no additional students, staff, or household contacts reported new diagnoses or symptoms of COVID-19 during the 2 weeks following screening testing. CONCLUSIONS: We identified infrequent asymptomatic COVID-19 in schools in high-risk Chicago communities and did not identify transmission among school staff, students, or their household contacts. These data suggest that COVID-19 mitigation procedures, including masking and physical distancing, are effective in preventing transmission of COVID-19 in schools. These results may inform future strategies for screening testing in K-8 schools.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19/diagnosis , Mass Screening , Schools , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19 Testing , Chicago/epidemiology , Faculty , Humans , Prospective Studies , Students
10.
Nihon Koshu Eisei Zasshi ; 68(8): 550-558, 2021 Aug 11.
Article in Japanese | MEDLINE | ID: covidwho-1352943

ABSTRACT

Objectives There is little evidence supporting the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from presymptomatic or asymptomatic SARS-CoV-2-infected individuals in Japan, where the incidence of SARS-CoV-2 infection is lower than that in other developed countries. This study aimed to determine whether SARS-CoV-2 transmission can occur from presymptomatic or asymptomatic SARS-CoV-2-infected individuals.Methods We surveyed all directors of Japanese public health centers for index cases and secondary patients who possibly contracted SARS-CoV-2 infection from a presymptomatic or asymptomatic SARS-CoV-2-infected individual who came under their care before June 20, 2020. The professional staff at the centers routinely perform contact tracing of infected persons based on the guidelines of the Infection Control Act. Four authors independently reviewed reports of 9 index cases of SARS-CoV-2-infected individuals with 17 secondary patients from 8 prefectures and examined the cases to determine whether transmission from a SARS-CoV-2-infected individual in the presymptomatic or asymptomatic state occurred.Results We reported 7 index cases with 13 secondary patients. 1) An elderly woman acquired SARS-CoV-2 infection from her sustained asymptomatic granddaughter at home, 2) 4 guests and 1 accompanying child waiting at a hair salon acquired infection from the presymptomatic female hair stylist, 3) 2 inpatients acquired infection from a presymptomatic nurse while providing nursing care in close contact, 4) an elderly couple acquired SARS-CoV-2 infection from their presymptomatic relative who was in the 50s during household care at their home, 5) a man acquired SARS-CoV-2 infection from a presymptomatic adult neighbor in an enclosed space with poor ventilation, 6) a presymptomatic man had transmitted infection to another man at a coffee shop while having a discussion on business, and 7) a man in his 50s acquired SARS-CoV-2 infection from a presymptomatic man during 50 minutes of close contact at their office and in a car. These secondary patients had no other likely routes of infection. The interval between the date of symptom onset in the presymptomatic index case and the secondary patient ranged from 2 to 6 days. The incidence rates at the time these infections occurred in the corresponding prefectures ranged from 0.00 to 6.56 cases/1 million person-days.Conclusion We report the first case of SARS-CoV-2 transmission from a sustained asymptomatic index case in Japan. All secondary patients came into close contact with presymptomatic index cases in areas with poor ventilation.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19/epidemiology , COVID-19/transmission , Carrier State/epidemiology , Carrier State/transmission , Contact Tracing , SARS-CoV-2 , Adult , Aged , Female , Humans , Infectious Disease Incubation Period , Japan/epidemiology , Male , Middle Aged , Young Adult
11.
Med Sci Monit ; 27: e930776, 2021 Oct 12.
Article in English | MEDLINE | ID: covidwho-1344551

ABSTRACT

During the coronavirus disease 2019 (COVID-19) pandemic due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, patients presented with COVID-19 pneumonia of varying severity. The phenomenon of severe hypoxemia without signs of respiratory distress is also known as silent or hidden hypoxemia. Although silent hypoxemia is not unique to pneumonia due to SARS-CoV-2 infection, this phenomenon is now recognized to be associated with severe COVID-19 pneumonia. Proper management of critically ill patients is the key to reducing mortality. Herein, we summarize the possible and rare factors contributing to silent hypoxemia in patients with COVID-19. Microvascular thrombosis causes dead space ventilation in the lungs, and the flow of pulmonary capillaries is reduced, which leads to an imbalance in the V/Q ratio. The dissociation curve of oxyhemoglobin shifts to the left and limits the release of oxygen to the tissue. SARS-CoV-2 interferes with the synthesis of hemoglobin and reduces the ability to carry oxygen. The accumulation of endogenous carbon monoxide and carboxyhemoglobin will reduce the total oxygen carrying capacity and interfere with pulse oxygen saturation readings. There are also some non-specific factors that cause the difference between pulse oximetry and oxygen partial pressure. We propose some potentially more effective clinical alternatives and recommendations for optimizing the clinical management processes of patients with COVID-19. This review aims to describe the prevalence of silent hypoxemia in COVID-19 pneumonia, to provide an update on what is known of the pathophysiology, and to highlight the importance of diagnosing silent hypoxemia in patients with COVID-19 pneumonia.


Subject(s)
COVID-19/metabolism , Hypoxia/virology , Pneumonia, Viral/virology , Asymptomatic Diseases/epidemiology , COVID-19/epidemiology , COVID-19/virology , Humans , Hypoxia/epidemiology , Hypoxia/metabolism , Lung/cytology , Lung/metabolism , Lung/virology , Microvessels/metabolism , Oximetry , Oxygen/metabolism , Pneumonia, Viral/metabolism , Prevalence , SARS-CoV-2/isolation & purification , Thrombosis/metabolism , Thrombosis/virology
12.
Scand J Trauma Resusc Emerg Med ; 29(1): 95, 2021 Jul 19.
Article in English | MEDLINE | ID: covidwho-1318289

ABSTRACT

BACKGROUND: There is a lack of knowledge how patients with COVID-19 disease differ from patients with similar signs or symptoms (but who will have a diagnosis other than COVID-19) in the prehospital setting. The aim of this study was to compare the characteristics of these two patient groups met by the emergency medical services. METHODS: All prehospital patients after the World Health Organisation (WHO) pandemic declaration 11.3.2020 until 30.6.2020 were recruited for the study. The patients were screened using modified WHO criteria for suspected COVID-19. Data from the electronic prehospital patient reporting system were linked with hospital laboratory results to check the laboratory confirmation for COVID-19. For comparison, we divided the patients into two groups: screening- and laboratory-positive patients with a hospital diagnosis of COVID-19 and screening-positive but laboratory-negative patients who eventually received a different diagnosis in hospital. RESULTS: A total of 4157 prehospital patients fulfilled the criteria for suspected COVID-19 infection during the study period. Five-hundred-thirty-six (12.9%) of the suspected cases received a laboratory confirmation for COVID-19. The proportion of positive cases in relation to suspected ones peaked during the first 2 weeks after the declaration of the pandemic. In the comparison of laboratory-positive and laboratory-negative cases, there were clinically insignificant differences between the groups in age, tympanic temperature, systolic blood pressure, heart rate, on-scene time, urgency category of the call and mode of transportation. Foreign-language-speakers were overrepresented amongst the positive cases over native language speakers (26,6% vs. 7,4%, p < 0,001). The number of cases in which no signs or symptoms of COVID-19 disease were reported, but patients turned out to have a positive test result was 125 (0,3% of the whole EMS patient population and 11,9% of all verified COVID-19 patients encountered by the EMS). CONCLUSIONS: In a sample of suspected COVID-19 patients, the laboratory-positive and laboratory-negative patients were clinically indistinguishable from each other during the prehospital assessment. Foreign-language-speakers had a high likelihood of having Covid-19. The modified WHO criteria still form the basis of screening of suspected COVID-19 patients in the prehospital setting.


Subject(s)
COVID-19/diagnosis , COVID-19/epidemiology , Emergency Medical Services , Adult , Age Factors , Aged , Asymptomatic Diseases/epidemiology , Blood Pressure , Body Temperature , COVID-19 Testing , Cohort Studies , Female , Finland/epidemiology , Heart Rate , Humans , Male , Middle Aged , Pandemics , Retrospective Studies , Systole
15.
Sci Rep ; 11(1): 12676, 2021 06 16.
Article in English | MEDLINE | ID: covidwho-1275954

ABSTRACT

Regular PCR testing of nasopharyngeal swabs from symptomatic individuals for SARS-CoV-2 virus has become the established method by which health services are managing the COVID-19 pandemic. Businesses such as AstraZeneca have also prioritised voluntary asymptomatic testing to keep workplaces safe and maintain supply of essential medicines to patients. We describe the development of an internal automated SARS-CoV-2 testing programme including the transformative introduction of saliva as an alternative sample type.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , COVID-19/epidemiology , Pandemics/prevention & control , Real-Time Polymerase Chain Reaction/methods , SARS-CoV-2/genetics , Saliva/virology , Workforce , COVID-19/virology , Diagnostic Tests, Routine/methods , Humans , Nasopharynx/virology , RNA, Viral/genetics , RNA, Viral/isolation & purification , Specimen Handling/methods
16.
Sci Rep ; 11(1): 10024, 2021 05 11.
Article in English | MEDLINE | ID: covidwho-1225517

ABSTRACT

We have studied the dynamic evolution of the Covid-19 pandemic in Argentina. The marked heterogeneity in population density and the very extensive geography of the country becomes a challenge itself. Standard compartment models fail when they are implemented in the Argentina case. We extended a previous successful model to describe the geographical spread of the AH1N1 influenza epidemic of 2009 in two essential ways: we added a stochastic local mobility mechanism, and we introduced a new compartment in order to take into account the isolation of infected asymptomatic detected people. Two fundamental parameters drive the dynamics: the time elapsed between contagious and isolation of infected individuals ([Formula: see text]) and the ratio of people isolated over the total infected ones (p). The evolution is more sensitive to the [Formula: see text]parameter. The model not only reproduces the real data but also predicts the second wave before the former vanishes. This effect is intrinsic of extensive countries with heterogeneous population density and interconnection.The model presented has proven to be a reliable predictor of the effects of public policies as, for instance, the unavoidable vaccination campaigns starting at present in the world an particularly in Argentina.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19/epidemiology , Models, Theoretical , Argentina/epidemiology , COVID-19/virology , Humans , Pandemics , SARS-CoV-2/isolation & purification
17.
Viruses ; 13(5)2021 04 30.
Article in English | MEDLINE | ID: covidwho-1217119

ABSTRACT

It is unclear whether universal PCR screening for SARS-CoV-2 in asymptomatic individuals prior to admission is useful. From April to December 2020, the positive rate of universal pre-admission screening was 0.005% (4/76,521) in a tertiary care hospital in Korea. The positive rates were not different between the periods (period 1 (daily new patients of <1 per million inhabitants) vs. period 2 (1-8.3 per million inhabitants) vs. period 3 (10.3 to 20 per million inhabitants); P = 0.45). Universal pre-admission screening for SARS-CoV-2 had a lower positive rate than that of symptom-based screening (0.005% vs. 0.049% (53/109,257), p < 0.001). In addition, seven patients with negative pre-admission test results had subsequent positive PCR during hospitalization, and four patients had secondary transmission. Universal pre-admission PCR screening may not be practical in settings of low prevalence of COVID-19, and negative PCR results at admission should not serve as a basis for underestimating the risk of nosocomial spread from asymptomatic patients.


Subject(s)
Asymptomatic Diseases/epidemiology , COVID-19 Nucleic Acid Testing/methods , COVID-19 , Carrier State , Nasopharynx/virology , SARS-CoV-2/isolation & purification , COVID-19/diagnosis , COVID-19/epidemiology , Carrier State/diagnosis , Carrier State/epidemiology , Humans , Prevalence , Republic of Korea/epidemiology , Tertiary Care Centers
18.
MMWR Morb Mortal Wkly Rep ; 70(17): 632-638, 2021 Apr 30.
Article in English | MEDLINE | ID: covidwho-1207942

ABSTRACT

Early studies suggest that COVID-19 vaccines protect against severe illness (1); however, postvaccination SARS-CoV-2 infections (i.e., breakthrough infections) can occur because COVID-19 vaccines do not offer 100% protection (2,3). Data evaluating the occurrence of breakthrough infections and impact of vaccination in decreasing transmission in congregate settings are limited. Skilled nursing facility (SNF) residents and staff members have been disproportionately affected by SARS-CoV-2, the virus that causes COVID-19 (4,5), and were prioritized for COVID-19 vaccination (6,7). Starting December 28, 2020, all 78 Chicago-based SNFs began COVID-19 vaccination clinics over several weeks through the federal Pharmacy Partnership for Long-Term Care Program (PPP).† In February 2021, through routine screening, the Chicago Department of Public Health (CDPH) identified a SARS-CoV-2 infection in a SNF resident >14 days after receipt of the second dose of a two-dose COVID-19 vaccination series. SARS-CoV-2 cases, vaccination status, and possible vaccine breakthrough infections were identified by matching facility reports with state case and vaccination registries. Among 627 persons with SARS-CoV-2 infection across 75 SNFs since vaccination clinics began, 22 SARS-CoV-2 infections were identified among 12 residents and 10 staff members across 15 facilities ≥14 days after receiving their second vaccine dose (i.e., breakthrough infections in fully vaccinated persons). Nearly two thirds (14 of 22; 64%) of persons with breakthrough infections were asymptomatic; two residents were hospitalized because of COVID-19, and one died. No facility-associated secondary transmission occurred. Although few SARS-CoV-2 infections in fully vaccinated persons were observed, these cases demonstrate the need for SNFs to follow recommended routine infection prevention and control practices and promote high vaccination coverage among SNF residents and staff members.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19/epidemiology , Occupational Diseases/epidemiology , Skilled Nursing Facilities , Adult , Aged , Asymptomatic Diseases/epidemiology , COVID-19/prevention & control , Chicago/epidemiology , Female , Humans , Immunization Schedule , Infection Control/organization & administration , Male , Middle Aged , Occupational Diseases/prevention & control
19.
Infect Dis Poverty ; 10(1): 56, 2021 Apr 26.
Article in English | MEDLINE | ID: covidwho-1204112

ABSTRACT

BACKGROUND: As one of the non-pharmacological interventions to control the transmission of COVID-19, determining the quarantine duration is mainly based on the accurate estimates of the incubation period. However, patients with coarse information of the exposure date, as well as infections other than the symptomatic, were not taken into account in previously published studies. Thus, by using the statistical method dealing with the interval-censored data, we assessed the quarantine duration for both common and uncommon infections. The latter type includes the presymptomatic, the asymptomatic and the recurrent test positive patients. METHODS: As of 10 December 2020, information on cases have been collected from the English and Chinese databases, including Pubmed, Google scholar, CNKI (China National Knowledge Infrastructure) and Wanfang. Official websites and medias were also searched as data sources. All data were transformed into doubly interval-censored and the accelerated failure time model was applied. By estimating the incubation period and the time-to-event distribution of worldwide COVID-19 patients, we obtain the large percentiles for determining and suggesting the quarantine policies. For symptomatic and presymptomatic COVID-19 patients, the incubation time is the duration from exposure to symptom onset. For the asymptomatic, we substitute the date of first positive result of nucleic acid testing for that of symptom onset. Furthermore, the time from hospital discharge or getting negative test result to the positive recurrence has been calculated for recurrent positive patients. RESULTS: A total of 1920 laboratory confirmed COVID-19 cases were included. Among all uncommon infections, 34.1% (n = 55) of them developed symptoms or were identified beyond fourteen days. Based on all collected cases, the 95th and 99th percentiles were estimated to be 16.2 days (95% CI 15.5-17.0) and 22.9 days (21.7‒24.3) respectively. Besides, we got similar estimates based on merely symptomatic and presymptomatic infections as 15.1 days (14.4‒15.7) and 21.1 days (20.0‒22.2). CONCLUSIONS: There are a certain number of infected people who require longer quarantine duration. Our findings well support the current practice of the extended active monitoring. To further prevent possible transmissions induced and facilitated by such infectious outliers after the 14-days quarantine, properly prolonging the quarantine duration could be prudent for high-risk scenarios and in regions with insufficient test resources.


Subject(s)
COVID-19/prevention & control , Quarantine/methods , SARS-CoV-2/physiology , Adolescent , Adult , Aged , Asymptomatic Diseases/epidemiology , Asymptomatic Infections/epidemiology , Carrier State/epidemiology , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Infectious Disease Incubation Period , Male , Middle Aged , Models, Statistical , Time Factors , Young Adult
20.
J Med Virol ; 93(3): 1776-1779, 2021 03.
Article in English | MEDLINE | ID: covidwho-1196479

ABSTRACT

Pediatric cases of the coronavirus disease 2019 (COVID-19) are generally mild or asymptomatic, and are usually detected by virological examination following close contact with COVID-19 patients, often the children's parents. The detailed clinical features and virological data of pediatric patients with COVID-19, particularly young infants, remain unclear. Here, the clinical and virological characteristics of four children with COVID-19 including two young infants were investigated. One- and 4-month-old boys with COVID-19 were both asymptomatic, and seroconversion was demonstrated. These findings suggest that even young infants can mount an immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), despite having weaker immune defenses than adolescents and adults. Three-year-old boy, who was SARS-CoV-2-negative, was admitted to the same room as his SARS-CoV-2-positive father due to the lack of caregivers. Although he was asymptomatic, he had seroconverted to SARS-CoV-2. Eleven-year-old boy, who was sibling of the 3-year-old boy, was also SARS-CoV-2-negative. He was isolated in his own room and did not seroconvert. If young children are SARS-CoV-2 negative, they should be isolated from their SARS-CoV-2-positive parents. This may be difficult in practice, if parents with COVID-19 are the only available caregivers. In such situations, the most appropriate measures should be taken for each patient.


Subject(s)
Antibodies, Viral/blood , Asymptomatic Diseases/epidemiology , COVID-19/immunology , SARS-CoV-2/immunology , Seroconversion , Child , Child, Preschool , Female , Hospitalization , Humans , Infant , Male , Nasopharynx/virology , Parents
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