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Household Transmission of SARS-CoV-2, Zhuhai, China, 2020
Abstract and Figures
Background:
To illustrate the extent of transmission, identify affecting risk factors and estimate epidemiological modeling parameters of SARS-CoV-2 in household setting.
Methods:
We enrolled 35 confirmed index cases and their 148 household contacts, January 2020-February 2020, in Zhuhai, China. All participants were interviewed and asked to complete questionnaires. Household contacts were then prospectively followed active symptom monitoring through the 21-day period and nasopharyngeal and/or oropharyngeal swabs were collected at 3-7 days intervals. Epidemiological, demographic and clinical data (when available) were collected.
Results:
Assuming that all these secondary cases were infected by their index cases, the second infection rate (SIR) in household context is 32.4% (95% confidence interval [CI] 22.4%-44.4%), with 10.4% of secondary cases being asymptomatic. Multivariate analysis showed that household contacts with underlying medical conditions, a history of direct exposure to Wuhan and its surrounding areas, and shared vehicle with an index patient were associated with higher susceptibility. Household members without protective measures after illness onset of the index patient seem to increase the risk for SARS-CoV-2 infection. The median incubation period and serial interval within household were estimated to be 4.3 days (95% CI; 3.4 to 5.3 days) and 5.1 days (95% CI; 4.3 to 6.2 days), respectively.
Conclusion:
Early isolation of patients with COVID-19 and prioritizing rapid contact investigation, followed by active symptom monitoring and periodic laboratory evaluation, should be initiated immediately after confirming patients to address the underlying determinants driving the continuing pandemic.
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... In our study, male preponderance was noted in both rural and urban areas (53.09%) and females (46.91%). In the study conducted by Jian Wu et al. (2021), males infected were 54.3% and females were 45.7%. [9] In studies conducted by Wi Li et al. (2020), males affected were 57.1% while females were 43.1%, which is comparable to our study. ...
... In the study conducted by Jian Wu et al. (2021), males infected were 54.3% and females were 45.7%. [9] In studies conducted by Wi Li et al. (2020), males affected were 57.1% while females were 43.1%, which is comparable to our study. [10] Males were affected more as compared to females because in a male-dominated society, the major population going out for work is male, so the chances of contracting infection are more in males. ...
Background
Coronavirus disease 2019 (COVID-19) pandemic began in India in 2020. Despite successful vaccination, cases again started increasing from mid-December 2021. Therefore, this study was undertaken to find out the clinico-epidemiological characteristics and effectiveness of vaccination in the household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in and around Pune.
Material and Methods
All samples received from December 15, 2021, till February 15, 2022, were included in the study. Samples received in viral transport medium (VTM) were extracted by the MagMAX RNA Extraction Kit, and reverse transcriptase–polymerase chain reaction (RT–PCR) was performed by the CoviPath Kit as per kit guidelines. Values of nucleocapsid (N) gene and open reading frame (ORF) less than 37 were considered positive. Clinico-epidemiological data were analyzed from the sample referral form (SRF).
Results
A total of 712 of 1032 household contacts of 271 families were positive. When geographical areas were compared, it was found that rural areas were affected more (63.76%) as compared to urban areas (36.24%). Males were more affected than females. The most commonly affected age group was 41–50 years (26.54%). Small families were found to have more household transmission. Mild symptoms were present in 97.89%. Among 271 infected individuals, seven were admitted to hospital, of which one patient died due to pneumonia. Two doses of vaccination were completed in 93.95%, and 3.79% had taken booster dose.
Conclusions
Data from this study showed that a high rate of transmission was observed in household contact despite two doses of vaccination. However, these vaccinated individuals had mild symptoms, maybe due to the effect of vaccination and infecting variant omicron.
... We use the mobile device data to estimate the average daily percentage of time that county residents spent indoors away-from-home. We use this measure as our primary description of transmission-relevant behavior because SARS-CoV-2 overwhelmingly occurs indoors [48,49], and, while the home environment is a key source of SARS-CoV-2 transmission, contacts outside of the home are necessary for introduction of the virus into the home [50]. Additionally, we conducted a sensitivity analysis using time at home as an alternate measure of transmission-relevant behavior, due to concern over potential misclassification that could arise when differentiating between time spent indoors versus outdoors. ...
There is growing evidence that weather alters SARS-CoV-2 transmission, but it remains unclear what drives the phenomenon. One prevailing hypothesis is that people spend more time indoors in cooler weather, leading to increased spread of SARS-CoV-2 related to time spent in confined spaces and close contact with others. However, the evidence in support of that hypothesis is limited and, at times, conflicting. We use a mediation framework, and combine daily weather, COVID-19 hospital surveillance, cellphone-based mobility data and building footprints to estimate the relationship between daily indoor and outdoor weather conditions, mobility, and COVID-19 hospitalizations. We quantify the direct health impacts of weather on COVID-19 hospitalizations and the indirect effects of weather via time spent indoors away-from-home on COVID-19 hospitalizations within five Colorado counties between March 4th 2020 and January 31st 2021. We also evaluated the evidence for seasonal effect modification by comparing the results of all-season (using season as a covariate) to season-stratified models. Four weather conditions were associated with both time spent indoors away-from-home and 12-day lagged COVID-19 hospital admissions in one or more season: high minimum temperature (all-season), low maximum temperature (spring), low minimum absolute humidity (winter), and high solar radiation (all-season & winter). In our mediation analyses, we found evidence that changes in 12-day lagged hospital admissions were primarily via the direct effects of weather conditions, rather than via indirect effects by which weather changes time spent indoors away-from-home. Our findings do not support the hypothesis that weather impacted SARS-CoV-2 transmission via changes in mobility patterns during the first year of the pandemic. Rather, weather appears to have impacted SARS-CoV-2 transmission primarily via mechanisms other than human movement. We recommend further analysis of this phenomenon to determine whether these findings generalize to current SARS-CoV-2 transmission dynamics, as well as other seasonal respiratory pathogens.
... However, it's important to note that a shortage of these necessities could hinder the maintenance of hygienic conditions in homes where COVID-19 patients are being managed. A study conducted in Beijing, China, demonstrated that infection prevention and control (IPC) measures could effectively prevent household COVID-19 transmission, even in crowded or small households [33]. Nevertheless, it is advisable to provide ongoing support | https://doi.org/10.1007/s44155-024-00060-w ...
Introduction
With the upsurge of COVID-19 cases, Lebanese hospitals were overburdened and hospital care was prioritized for COVID-19 patients with the highest probability of poor outcomes. This paper aimed to assess the suitability of residential settings for home isolation and to explore the patient’s ability to adhere to the required precautions measures.
Methods
All COVID-19 cases reported between February, 21 and the end of June 2020 and who had mild or moderate symptoms, were contacted via phone calls by a healthcare professional to fill out a standardized questionnaire developed to assess the suitability of the residential setting for home care. Inpatient cases were required, before their discharge from the hospitals, to sign consent related to their adherence to the mandatory precautionary measures. They were also asked to complete, on daily basis, the symptoms monitoring log form. A referral system to health facilities was established to manage cases with worsening health status. A collaborative framework to address violations of home isolation rules was also put in place.
Results
Of the 600 cases assessed, 44.7% of them were isolated in a living building apartment (67.2%) with one entrance (85.5%) including four to eight rooms (71%). Around one-quarter of patients have children (< 5 years) and 75% of them were living with elderly people. Most of the patients confirmed the availability of a well-ventilated single room (96.2%) and a separate bathroom (80.17%). As for infrastructure, more than 90% of patients confirmed the availability of drinking and tank water, heating facilities, electricity, and safe trash elimination. Similarly, more than 90% of them had access to personal hygiene items, disinfectants, and personal protective equipment. The bulk of homes care were rated as easily reachable. As for awareness and ability to self-serving, 94.5% of patients were knowledgeable about the required preventive measures, able to serve themselves and to adhere to the isolation requirements as well. Only 51.8% of them had access to psychological support.
Conclusion
Proper assessment of the residential setting for home care of COVID-19 cases combined with close monitoring of the adherence of patients to the required precaution measures are highly needed for limiting the spread of infection within the household and the community.
... 15 Similar secondary infection rates have been reported in China. 16 It could be argued that the subjects of these research were not home-isolating at the time of the secondary infection within their household, but it does not undermine the fact that at least 60-70% of transmission was within households; 10 times more than any other single route. 17 Since home-isolation is solely hinged on the personal compliance of an individual, therefore it inevitably could lead to increased transmission. ...
Objectives: To assess compliance level of coronavirus disease-2019 patients with recommended isolation guidelines. Methods: The cross-sectional phone-based survey was conducted in Karachi, from March to October 2020 after approval from the ethics review board of Dow University of Health Sciences, Karachi, and comprised patients of either gender who had been tested positive and were advised home isolation due to mild/asymptomatic nature of their infection. Data was collected using a predesigned 42-item questionnaire in the light of the guidelines issued by the National Institutes of Health, Islamabad, Pakistan. Data was analysed using SPSS 20. Results: Of the 450 patients approached, 305(68%) responded; 176(57.7%) females and 129(41.1%) males. The overall mean age was 35.16+/-14.15 years (range: 13-78 years). Of the total, 9(2.95%) patients did not isolate themselves at all, 51(16.7%) came into contact with other people, 75(24.6%) broke the home isolation and 69(22.6%) were sharing their rooms with other family members. Overall, 260(85.2%) participants were keeping themselves updated with the changes in the guidelines through conventional and social media. Conclusion: Coronavirus disease-2019 patients who were advised home isolation adhered to some but not all of the recommendations. Key Words: COVID-19, Home isolation, Protective measures, Home management, SARS-CoV-2.
... Vaccination reduces the risk of COVID-19 transmission, infection and severity of infection in people of the same household, 12,13 and the transmission rate between roommates and between household members may be comparable. 6,7,14,15 There is little published information on nosocomial transmission in New Zealand, although several hospital outbreaks have occurred with an estimated 30-50% of contacts in multi-bed rooms becoming infected (H McGann, personal communication). This suggests that separating patients by vaccination status may reduce the spread of an outbreak before diagnosis has taken place. ...
This paper presents quasiexperimental evidence of Covid-19 transmission through casual contact between customers in retail stores. For a large sample of individuals in Denmark, we match card payment data, indicating exactly where and when each individual made purchases, with Covid-19 test data, indicating when each individual was tested and whether the test was positive. The resulting dataset identifies more than 100,000 instances where an infected individual made a purchase in a store and, in each instance, allows us to track the infection dynamics of other individuals who made purchases in the same store around the same time. We estimate transmissions by comparing the infection rate of exposed customers, who made a purchase within 5 min of an infected individual, and nonexposed customers, who made a purchase in the same store 16 to 30 min before. We find that exposure to an infected individual in a store increases the infection rate by around 0.12 percentage points ( P < 0.001) between day 3 and day 7 after exposure. The estimates imply that transmissions in stores contributed around 0.04 to the reproduction number for the average infected individual and significantly more in the period where Omicron was the dominant variant.
Introducción:
Las políticas de salud pública para la disminución de la incidencia, transmisión y mortalidad de la COVID-19 se enfocan en medidas extradomiciliarias y descuidan el contagio dentro del hogar. El objetivo fue estimar la tasa de ataque secundario domiciliario de SARS-CoV-2.
Material y Métodos:
Se realizó una revisión sistemática de estudios observacionales que evaluaron la transmisión domiciliaria de SARS-CoV-2 publicados entre diciembre de 2019 y el 1 setiembre de 2021 en las bases de datos Medline, Scopus, LILACS y Google Scholar. La definición de contacto domiciliario se refirió a toda persona que habitaba la misma vivienda que el paciente índice. El riesgo de sesgo fue evaluado con una versión modificada de la escala Newcastle-Ottawa. Se realizó un metaanálisis con un modelo de efectos aleatorios para calcular la tasa de ataque domiciliaria, subanálisis con variables sociodemográficas, epidemiológicas y comorbilidades, así como metaregresión.
Resultados:
De 4491 estudios encontrados, 44 fueron incluidos en el análisis. La tasa de ataque secundario domiciliario general fue de 27.7% (IC95%: 23% 32.7%). Además, fue mayor cuando el caso índice era sintomático (28.3%, IC95%: 8.1% 54.7%) o el contacto era adulto mayor (42.3%, IC95%: 32% 52.9%). Asimismo, la tasa fue mayor cuando los contactos domiciliarios presentaban diabetes mellitus (57.4%, IC95%: 45.2% 69.3%) e hipertensión arterial (51.1%, IC95%: 38% 64.1%).
Conclusiones:
La tasa de ataque secundario domiciliario de SARS-CoV-2 fue de 27.7%, siendo mayor al tener un caso índice adulto, contacto adulto mayor y contacto con diabetes mellitus o hipertensión arterial.
Background: There is growing evidence that weather alters SARS-CoV-2 transmission, but it remains unclear what drives the phenomenon. One prevailing hypothesis is that people spend more time indoors in cooler weather, leading to increased spread of SARS-CoV-2 related to time spent in confined spaces and close contact with others. However, the evidence in support of that hypothesis is limited and, at times, conflicting.
Objectives: We aim to evaluate the extent to which weather impacts COVID-19 via time spent away-from-home in indoor spaces, as compared to a direct effect of weather on COVID-19 hospitalization, independent of mobility.
Methods: We use a mediation framework, and combine daily weather, COVID-19 hospital surveillance, cellphone-based mobility data and building footprints to estimate the relationship between daily indoor and outdoor weather conditions, mobility, and COVID-19 hospitalizations. We quantify the direct health impacts of weather on COVID-19 hospitalizations and the indirect effects of weather via time spent indoors away-from-home on COVID-19 hospitalizations within five Colorado counties between March 4th 2020 and January 31st 2021.
Results: We found evidence that changes in 12-day lagged hospital admissions were primarily via the direct effects of weather conditions, rather than via indirect effects by which weather changes time spent indoors away-from-home. Sensitivity analyses evaluating time at home as a mediator were consistent with these conclusions.
Discussion: Our findings do not support the hypothesis that weather impacted SARS-CoV-2 transmission via changes in mobility patterns during the first year of the pandemic. Rather, weather appears to have impacted SARS-CoV-2 transmission primarily via mechanisms other than human movement. We recommend further analysis of this phenomenon to determine whether these findings generalize to current SARS-CoV-2 transmission dynamics and other seasonal respiratory pathogens.
Background
Households are considered ideal settings for studying the transmission dynamics of an infectious disease.
Methods
A prospective study was conducted, based on the World Health Organization FFX protocol from October 2020 to January,2021. Household contacts of laboratory-confirmed index cases were followed up for their symptomatic history, nasal swabs for RT-PCR,and blood samples for anti-SARS CoV-2 antibodies were collected at enrollment and days 7, 14 and 28. We estimated secondary attack rate (SAR), effective household case cluster size and determinants of secondary infection among susceptible household contacts using multivariable logistic regression.
Results
We enrolled 77 index cases and their 543 contacts. Out of these, 252 contacts were susceptible at the time of enrollment. There were 77 household clusters, out of which, transmission took place in 20 (25.9%) giving rise to 34 cases. The acquired secondary attack rate (SAR) was 14.0% (95% CI 9.0–18.0). The effective household case cluster size was 0.46 (95%CI 0.33,0.56). Reported symptoms of nausea and vomiting (aOR, 7.9; 95% CI, 1.4–45.5) and fatigue (aOR, 9.3; 95% CI, 3.8–22.7) were associated with SARS-CoV-2 transmission.
Conclusions
We observed a low SARS-CoV-2 secondary attack rate in the backdrop of high seroprevalence and asymptomatic transmission among households in Karachi, Pakistan.
We report temporal patterns of viral shedding in 94 patients with laboratory-confirmed COVID-19 and modeled COVID-19 infectiousness profiles from a separate sample of 77 infector–infectee transmission pairs. We observed the highest viral load in throat swabs at the time of symptom onset, and inferred that infectiousness peaked on or before symptom onset. We estimated that 44% (95% confidence interval, 25–69%) of secondary cases were infected during the index cases’ presymptomatic stage, in settings with substantial household clustering, active case finding and quarantine outside the home. Disease control measures should be adjusted to account for probable substantial presymptomatic transmission. Presymptomatic transmission of SARS-CoV-2 is estimated to account for a substantial proportion of COVID-19 cases.
Globally, approximately 170,000 confirmed cases of coronavirus disease 2019 (COVID-19) caused by the 2019 novel coronavirus (SARS-CoV-2) have been reported, including an estimated 7,000 deaths in approximately 150 countries (1). On March 11, 2020, the World Health Organization declared the COVID-19 outbreak a pandemic (2). Data from China have indicated that older adults, particularly those with serious underlying health conditions, are at higher risk for severe COVID-19-associated illness and death than are younger persons (3). Although the majority of reported COVID-19 cases in China were mild (81%), approximately 80% of deaths occurred among adults aged ≥60 years; only one (0.1%) death occurred in a person aged ≤19 years (3). In this report, COVID-19 cases in the United States that occurred during February 12-March 16, 2020 and severity of disease (hospitalization, admission to intensive care unit [ICU], and death) were analyzed by age group. As of March 16, a total of 4,226 COVID-19 cases in the United States had been reported to CDC, with multiple cases reported among older adults living in long-term care facilities (4). Overall, 31% of cases, 45% of hospitalizations, 53% of ICU admissions, and 80% of deaths associated with COVID-19 were among adults aged ≥65 years with the highest percentage of severe outcomes among persons aged ≥85 years. In contrast, no ICU admissions or deaths were reported among persons aged ≤19 years. Similar to reports from other countries, this finding suggests that the risk for serious disease and death from COVID-19 is higher in older age groups.
On 31 st December 2019, the World Health Organization was informed of a cluster of cases of pneumonia of unknown etiology in Wuhan, China. Subsequent investigations identified a novel coronavirus, now named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), from the affected patients. Highly sensitive and specific laboratory diagnostics are important for controlling the rapidly evolving SARS-CoV-2-associated Coronavirus Disease 2019 (COVID-19) epidemic. In this study, we developed and compared the performance of three novel real-time RT-PCR assays targeting the RNA-dependent RNA polymerase (RdRp)/helicase (Hel), spike (S), and nucleocapsid (N) genes of SARS-CoV-2 with that of the reported RdRp-P2 assay which is used in >30 European laboratories. Among the three novel assays, the COVID-19-RdRp/Hel assay had the lowest limit of detection in vitro (1.8 TCID 50 /ml with genomic RNA and 11.2 RNA copies/reaction with in vitro RNA transcripts). Among 273 specimens from 15 patients with laboratory-confirmed COVID-19 in Hong Kong, 77 (28.2%) were positive by both the COVID-19-RdRp/Hel and RdRp-P2 assays. The COVID-19-RdRp/Hel assay was positive for an additional 42 RdRd-P2-negative specimens [119/273 (43.6%) vs 77/273 (28.2%), P<0.001], including 29/120 (24.2%) respiratory tract specimens and 13/153 (8.5%) non-respiratory tract specimens. The mean viral load of these specimens was 3.21×10 ⁴ RNA copies/ml (range, 2.21×10 ² to 4.71×10 ⁵ RNA copies/ml). The COVID-19-RdRp/Hel assay did not cross-react with other human-pathogenic coronaviruses and respiratory pathogens in cell culture and clinical specimens, whereas the RdRp-P2 assay cross-reacted with SARS-CoV in cell culture. The highly sensitive and specific COVID-19-RdRp/Hel assay may help to improve the laboratory diagnosis of COVID-19.
Background
Rapid spread of SARS-CoV-2 in Wuhan prompted heightened surveillance in Shenzhen and elsewhere in China. The resulting data provide a rare opportunity to measure key metrics of disease course, transmission, and the impact of control.
Methods
The Shenzhen CDC identified 391 SARS-CoV-2 cases from January 14 to February 12, 2020 and 1286 close contacts. We compare cases identified through symptomatic surveillance and contact tracing, and estimate the time from symptom onset to confirmation, isolation, and hospitalization. We estimate metrics of disease transmission and analyze factors influencing transmission risk.
Findings
Cases were older than the general population (mean age 45) and balanced between males (187) and females (204). Ninety-one percent had mild or moderate clinical severity at initial assessment. Three have died, 225 have recovered (median time to recovery is 32 days). Cases were isolated on average 4.6 days after developing symptoms; contact tracing reduced this by 1.9 days. Household contacts and those travelling with a case where at higher risk of infection (ORs 6 and 7) than other close contacts. The household secondary attack rate was 15%, and children were as likely to be infected as adults. The observed reproductive number was 0.4, with a mean serial interval of 6.3 days.
Interpretation
Our data on cases as well as their infected and uninfected close contacts provide key insights into SARS-CoV-2 epidemiology. This work shows that heightened surveillance and isolation, particularly contact tracing, reduces the time cases are infectious in the community, thereby reducing R. Its overall impact, however, is uncertain and highly dependent on the number of asymptomatic cases. We further show that children are at similar risk of infection as the general population, though less likely to have severe symptoms; hence should be considered in analyses of transmission and control.
Objective
To estimate the serial interval of novel coronavirus (COVID-19) from information on 28 infector-infectee pairs.
Methods
We collected dates of illness onset for primary cases (infectors) and secondary cases (infectees) from published research articles and case investigation reports. We subjectively ranked the credibility of the data and performed analyses on both the full dataset (n = 28) and a subset of pairs with highest certainty in reporting (n = 18). In addition, we adjust for right truncation of the data as the epidemic is still in its growth phase.
Results
Accounting for right truncation and analyzing all pairs, we estimated the median serial interval at 4.0 days (95% credible interval [CrI]: 3.1, 4.9). Limiting our data to only the most certain pairs, the median serial interval was estimated at 4.6 days (95% CrI: 3.5, 5.9).
Conclusions
The serial interval of COVID-19 is close to or shorter than its median incubation period. This suggests that a substantial proportion of secondary transmission may occur prior to illness onset. The COVID-19 serial interval is also shorter than the serial interval of severe acute respiratory syndrome (SARS), indicating that calculations made using the SARS serial interval may introduce bias.
Background
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused an epidemic in China and many other countries. Many infected clusters have been found within familial households, but the data about secondary transmission among household contacts is limited.
Methods
In this retrospective case series, we enrolled 85 patients infected with SARS-CoV-2 and their household members in Wuhan. Patients were confirmed infected with SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (RT-PCR) assays on throat swabs. Epidemiological, clinical and laboratory data of the household members were collected.
Results
There were 155 close contacts in total. 104 contacts received RT-PCR assays, with 47 (30%) positive cases and 57 (37%) negative cases. 51 (33%) cases did not received RT-PCR tests for they showed no symptoms of pneumonia during the 2 weeks of quarantine. The infection rate of close contacts was 38% for households with 1 contact, 50% for households with 2 contacts, and 31% for households with 3 contacts.
Conclusions
The rate of secondary transmission among household contacts of patients with SARS-CoV-2 infection was 30%. Our data provide insight into the rate of secondary transmission of SARS-CoV-2 in home.
Background
Since December, 2019, Wuhan, China, has experienced an outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Epidemiological and clinical characteristics of patients with COVID-19 have been reported but risk factors for mortality and a detailed clinical course of illness, including viral shedding, have not been well described.
Methods
In this retrospective, multicentre cohort study, we included all adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China) who had been discharged or had died by Jan 31, 2020. Demographic, clinical, treatment, and laboratory data, including serial samples for viral RNA detection, were extracted from electronic medical records and compared between survivors and non-survivors. We used univariable and multivariable logistic regression methods to explore the risk factors associated with in-hospital death.
Findings
191 patients (135 from Jinyintan Hospital and 56 from Wuhan Pulmonary Hospital) were included in this study, of whom 137 were discharged and 54 died in hospital. 91 (48%) patients had a comorbidity, with hypertension being the most common (58 [30%] patients), followed by diabetes (36 [19%] patients) and coronary heart disease (15 [8%] patients). Multivariable regression showed increasing odds of in-hospital death associated with older age (odds ratio 1·10, 95% CI 1·03–1·17, per year increase; p=0·0043), higher Sequential Organ Failure Assessment (SOFA) score (5·65, 2·61–12·23; p<0·0001), and d-dimer greater than 1 μg/L (18·42, 2·64–128·55; p=0·0033) on admission. Median duration of viral shedding was 20·0 days (IQR 17·0–24·0) in survivors, but SARS-CoV-2 was detectable until death in non-survivors. The longest observed duration of viral shedding in survivors was 37 days.
Interpretation
The potential risk factors of older age, high SOFA score, and d-dimer greater than 1 μg/L could help clinicians to identify patients with poor prognosis at an early stage. Prolonged viral shedding provides the rationale for a strategy of isolation of infected patients and optimal antiviral interventions in the future.
Funding
Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences; National Science Grant for Distinguished Young Scholars; National Key Research and Development Program of China; The Beijing Science and Technology Project; and Major Projects of National Science and Technology on New Drug Creation and Development.
Background:
A novel human coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was identified in China in December 2019. There is limited support for many of its key epidemiologic features, including the incubation period for clinical disease (coronavirus disease 2019 [COVID-19]), which has important implications for surveillance and control activities.
Objective:
To estimate the length of the incubation period of COVID-19 and describe its public health implications.
Design:
Pooled analysis of confirmed COVID-19 cases reported between 4 January 2020 and 24 February 2020.
Setting:
News reports and press releases from 50 provinces, regions, and countries outside Wuhan, Hubei province, China.
Participants:
Persons with confirmed SARS-CoV-2 infection outside Hubei province, China.
Measurements:
Patient demographic characteristics and dates and times of possible exposure, symptom onset, fever onset, and hospitalization.
Results:
There were 181 confirmed cases with identifiable exposure and symptom onset windows to estimate the incubation period of COVID-19. The median incubation period was estimated to be 5.1 days (95% CI, 4.5 to 5.8 days), and 97.5% of those who develop symptoms will do so within 11.5 days (CI, 8.2 to 15.6 days) of infection. These estimates imply that, under conservative assumptions, 101 out of every 10 000 cases (99th percentile, 482) will develop symptoms after 14 days of active monitoring or quarantine.
Limitation:
Publicly reported cases may overrepresent severe cases, the incubation period for which may differ from that of mild cases.
Conclusion:
This work provides additional evidence for a median incubation period for COVID-19 of approximately 5 days, similar to SARS. Our results support current proposals for the length of quarantine or active monitoring of persons potentially exposed to SARS-CoV-2, although longer monitoring periods might be justified in extreme cases.
Primary funding source:
U.S. Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases, National Institute of General Medical Sciences, and Alexander von Humboldt Foundation.
In December 2019, an outbreak of coronavirus disease 2019 (COVID-19), caused by the virus SARS-CoV-2, began in Wuhan, China (1). The disease spread widely in China, and, as of February 26, 2020, COVID-19 cases had been identified in 36 other countries and territories, including the United States. Person-to-person transmission has been widely documented, and a limited number of countries have reported sustained person-to-person spread.* On January 20, state and local health departments in the United States, in collaboration with teams deployed from CDC, began identifying and monitoring all persons considered to have had close contact† with patients with confirmed COVID-19 (2). The aims of these efforts were to ensure rapid evaluation and care of patients, limit further transmission, and better understand risk factors for transmission.