Transmission dynamics of SARS-CoV-2 in a mid-size city of China

Abstract Background An outbreak of pneumonia, COVID-19 associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city and then rapidly spread to other cities. Wenzhou is located approximately 900 km from Wuhan, which was experiencing an outbreak that was severe at the time but is considered modest as the epidemic became a pandemic. We described the epidemiological characteristics of SARS-CoV-2 outside of the epicenter to help understand the transmission pattern in a mid-sized Chinese city. Methods To investigate the epidemiological and clinical characteristics of the COVID-19, we described case series of 473 patients with confirmed COVID-19 in Wenzhou, China from January 27 to March 16, 2020. We described the public health interventions of COVID-19 and evaluated the effect of interventions by the effective reproduction number (Rt). Results The median age of all patients was 47.6 years, 48.4% of whom were female. 33.8% of the patients had a history of residence in Wuhan. Fever (71.7%) and cough (43.1%) were the most common symptoms. In addition, three kinds of unconventional cases were observed, namely 4.9% asymptomatic patients, 7.6% confirmed patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact, and 12.9% confirmed patients who had an unknown source of transmission. We estimated that the basic reproductive number (R0) was 2.75 (95% CI: 2.37–3.23). The Rt fluctuated within the range of 2.50 to 3.74 from January 11 to January 16 while gradually reached a peak of 3.74 on January 16. Rt gradually decreased after January 16 and decreased to 1.00 on January 30. Rt continually decreased and reached the lowest point (0.03) on February 21, 2020. Conclusion Our study presented the possibility of asymptomatic carriers affected with SARS-CoV-2, and transmission by these three kinds of unconventional patients in Wenzhou may be an important characteristic of SARS-CoV-2 transmission. The evaluation showed that a series of multifaceted interventions proved effective in controlling the epidemic of COVID-19. These findings might provide valuable examples of control policies for countries or areas in combatting the global pandemic of COVID-19.

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Transmission Dynamics of SARS-CoV-2 in a Mid-size City of China

10.21203/rs.3.rs-59402/v1 ◽

2020 ◽

Author(s):

Hongjun Zhao ◽

Xiaoxiao Lu ◽

Wenhui Lun ◽

Tiegang Li ◽

Boqi Rao ◽

...

Keyword(s):

Reproduction Number ◽

Case Series ◽

Basic Reproductive Number ◽

Reproductive Number ◽

Wuhan City ◽

Asymptomatic Patients ◽

The World ◽

History Of ◽

And Control ◽

Epidemiological Characteristics

Abstract Background: An outbreak of pneumonia associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city and then spread to other cities. It is very urgent to delineate the epidemiological and clinical characteristics of these affected patients. Methods: To investigate the epidemiological characteristics of the COVID-19, we describe a case series of 473 patients with confirmed COVID-19 in Wenzhou of China from January 27 to March 2, 2020.Results: The median age of all patients was 47.6 years, 48.4% of which were female. 33.8% of the patients had a history of residence in Wuhan. Fever (71.7%) and cough (43.1%) were the most common symptoms. In addition, three kinds of unconventional cases were observed, namely 4.9% asymptomatic patients, 7.6% confirmed patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact, and 12.9% confirmed patients who had an unknown source of transmission. We estimated that the basic reproductive number (R0) was 2.75 (95%CI: 2.37-3.23). The effective reproduction number (Rt) fluctuated within the range of 2.50 to 3.74 from January 11 to January 16 while gradually reached the peak of 3.74 on January 16. Rt gradually decreased after January 16 and decreased to 1.00 on January 30. Rt continually decreased and reached the lowest point (0.03) on February 21, 2020.Conclusion: Our findings presented the possibility of asymptomatic carriers affected with SARS-CoV-2, and this phenomenon suggested that chances of uncontrollable transmission in the larger population might be higher than formerly estimated, and transmission by these three kinds of unconventional patients in Wenzhou may be an important characteristic of infection in other mid-sized cities in the world. This study evaluated the epidemic characteristics of Wenzhou after having cases imported from Hubei Province and the effects after adopting a series of strict prevention and control strategy.

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Transmission dynamics of SARS-COV-2 in China: impact of public health interventions

10.1101/2020.03.24.20036285 ◽

2020 ◽

Cited By ~ 1

Author(s):

Wenbao Wang ◽

Yiqin Chen ◽

Qi Wang ◽

Ping Cai ◽

Ye He ◽

...

Keyword(s):

Public Health ◽

Health Interventions ◽

Basic Reproductive Number ◽

Reproductive Number ◽

Public Health Interventions ◽

The Public ◽

Global Pandemic ◽

Actual Growth ◽

Global Threat ◽

The Impact

AbstractCOVID-19 has become a global pandemic. However, the impact of the public health interventions in China needs to be evaluated. We established a SEIRD model to simulate the transmission trend of China. In addition, the reduction of the reproductive number was estimated under the current forty public health interventions policies. Furthermore, the infection curve, daily transmission replication curve, and the trend of cumulative confirmed cases were used to evaluate the effects of the public health interventions. Our results showed that the SEIRD curve model we established had a good fit and the basic reproductive number is 3.38 (95% CI, 3.25–3.48). The SEIRD curve show a small difference between the simulated number of cases and the actual number; the correlation index (H2) is 0.934, and the reproductive number (R) has been reduced from 3.38 to 0.5 under the current forty public health interventions policies of China. The actual growth curve of new cases, the virus infection curve, and the daily transmission replication curve were significantly going down under the current public health interventions. Our results suggest that the current public health interventions of China are effective and should be maintained until COVID-19 is no longer considered a global threat.

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Transmission Dynamics of SARS-CoV-2 in a Mid-size City of China

10.21203/rs.2.23945/v3 ◽

2020 ◽

Author(s):

Zhao Hongjun ◽

Xiaoxiao Lu ◽

Tiegang Li ◽

Boqi Rao ◽

Dedong Wang ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Clinical Characteristics ◽

Case Series ◽

Transmission Dynamics ◽

Wuhan City ◽

Intimate Contact ◽

Epidemic Area ◽

History Of ◽

Epidemiological Characteristics ◽

Virus Carrier

Abstract Background: An outbreak of pneumonia associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan city and then to other city. It is very urgent to delineate the epidemiological and clinical characteristics of these affected patients. Methods: To investigate the epidemiological characteristics of the COVID-19, we describe a case series of 459 patients with confirmed COVID-19 in WZ of China from January 27 to February 12, 2020.Results: The median age of all patients was 48.0 years, and 46.8% were females. 37.5% of patients had a history of residence in Wuhan. Fever (72.1%) and cough (43.6%) were the most frequent symptoms. In addition, three kinds of unconventional cases were observed, in which included 4.4% confirmed virus carrier who were asymptomatic, 7.8% confirmed patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact, and 10.7% confirmed patients who had no link to Wuhan city nor a history of intimate contact with patients or individuals from Wuhan without any symptoms, respectively.Conclusion: Our findings presented the possibility of asymptomatic carriers affected with SARS-CoV-2, and this phenomenon suggested that chances of uncontrollable transmission in the larger population might be higher than formerly estimated, and transmission by these three kinds of unconventional patients in WZ may be one of the characteristics of infection in other Chinese cities outside the Wuhan epidemic area.

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SARS-CoV-2 in peritoneal swabs from asymptomatic patients undergoing emergency abdominal surgery

Journal of Surgical Case Reports ◽

10.1093/jscr/rjab116 ◽

2021 ◽

Vol 2021 (4) ◽

Author(s):

Jasim AlAradi ◽

Rawan A Rahman AlHarmi ◽

Mariam AlKooheji ◽

Sayed Ali Almahari ◽

Mohamed Abdulla Isa ◽

...

Keyword(s):

Peritoneal Fluid ◽

Case Series ◽

Rapid Test ◽

Nasopharyngeal Swab ◽

Rt Pcr ◽

Protective Measures ◽

The Public ◽

Asymptomatic Patients ◽

Number Of Patients ◽

Viral Transfer

Abstract This is a case series of five patients with acute abdomen requiring surgery who tested positive for coronavirus disease 2019 (COVID-19) and were asymptomatic, with the purpose of detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in peritoneal fluid. Nasopharyngeal swab was done as a prerequisite for admission or prior to admission as part of random testing. Two methods of viral testing were employed: Xpert® Xpress SARS-CoV-2 (rapid test) and real-time reverse transcription polymerase chain reaction (RT-PCR). Either or both tests were done, with the former performed for patients requiring surgery immediately. Surgery was performed within 24–36 h from admission. Peritoneal fluid swabs were obtained for the detection of SARS-CoV-2 using RT-PCR test. Swabs were immediately placed in viral transfer media and delivered to the public health laboratory in an ice bag. SARS-CoV-2 was not detected in peritoneal swabs. Due to the limited number of patients, further studies are required; yet, protective measures should still be taken by surgeons when dealing with COVID-19 cases.

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High incidence of asymptomatic SARS-CoV-2 infection, Chongqing, China

10.1101/2020.03.16.20037259 ◽

2020 ◽

Cited By ~ 4

Author(s):

Yang Tao ◽

Panke Cheng ◽

Wen Chen ◽

Peng Wan ◽

Yaokai Chen ◽

...

Keyword(s):

Asymptomatic Patient ◽

Medical Center ◽

Age Groups ◽

The Elderly ◽

Hospital Length ◽

Hospital Length Of Stay ◽

Asymptomatic Patients ◽

Imported Cases ◽

History Of ◽

Epidemiological Characteristics

SummaryBackgroundSARS-CoV-2 has been a global pandemic, but the emergence of asymptomatic patients has caused difficulties in the prevention of the epidemic. Therefore, it is significant to understand the epidemiological characteristics of asymptomatic patients with SARS-CoV-2 infection.MethodsIn this single-center, retrospective and observational study, we collected data from 167 patients with SARS-CoV-2 infection treated in Chongqing Public Health Medical Center (Chongqing, China) from January to March 2020. The epidemiological characteristics and variable of these patients were collected and analyzed.Findings82.04% of the SARS-CoV-2 infected patients had a travel history in Wuhan or a history of contact with returnees from Wuhan, showing typical characteristics of imported cases, and the proportion of severe Covid-19 patients was 13.2%, of which 59% were imported from Wuhan. For the patients who was returnees from Wuhan, 18.1% was asymptomatic patients. In different infection periods, compared with the proportion after 1/31/2020, the proportion of asymptomatic patient among SARS-CoV-2 infected patient was higher(19% VS 1.5%). In different age groups, the proportion of asymptomatic patient was the highest(28.6%) in children group under 14, next in elder group over 70 (27.3%). Compared with mild and common Covid-19 patients, the mean latency of asymptomatic was longer (11.25 days VS 8.86 days), but the hospital length of stay was shorter (14.3 days VS 16.96 days).ConclusionThe SARS-CoV-2 prevention needs to focus on the screening of asymptomatic patients in the community with a history of contact with the imported population, especially for children and the elderly population.

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Successive Bloodmeals Enhance Virus Dissemination Within Mosquitoes And Increase Transmission Potential

10.1101/246306 ◽

2018 ◽

Cited By ~ 3

Author(s):

Philip M. Armstrong ◽

Hanna Ehrlich ◽

Angela Bransfield ◽

Joshua L. Warren ◽

Virginia E. Pitzer ◽

...

Keyword(s):

Vector Competence ◽

Basic Reproductive Number ◽

Reproductive Number ◽

Transmission Potential ◽

The Public ◽

Virus Dissemination ◽

Virus Escape ◽

Extrinsic Incubation Period ◽

And Behavior ◽

Transmission Status

SUMMARY PARAGRAPHThe recent Zika virus (ZIKV) and chikungunya virus (CHIKV) epidemics highlight the explosive nature of arthropod-borne (arbo) viruses transmitted by Aedes aegypti mosquitoes1,2. Vector competence and the extrinsic incubation period (EIP) are two key entomological parameters used to assess the public health risk posed by arboviruses3. These are typically measured empirically by offering mosquitoes an infectious bloodmeal and temporally sampling mosquitoes to determine infection and transmission status. This approach has been used for the better part of a century; however, it does not accurately capture the biology and behavior of many mosquito vectors which refeed frequently (every 2-3 days)4. Here we demonstrate that administration of a second non-infectious bloodmeal significantly shortens the EIP of ZIKV-infected Ae. aegypti by enhancing virus escape from the mosquito midgut. Similarly, a second bloodmeal increased the competence of this species for dengue virus and CHIKV. This effect was also observed for ZIKV in Aedes albopictus, suggesting that this species might be a more important vector than once thought and that this phenomenon may be common among other virus-vector pairings. Modeling of these findings reveals that a shortened EIP would result in a significant increase in the basic reproductive number, R0. This increase helps explain how Ae.aegypti can sustain an explosive epidemic like ZIKV despite its relatively poor vector competence in single-feed laboratory trials. Together, these data demonstrate a direct and unrecognized link between mosquito feeding behavior, EIP, and vector competence.

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The effects of the clinical symptoms pneumonia-confirmation strategy of the COVID-19 epidemic in Wuhan, China

10.21203/rs.3.rs-28619/v1 ◽

2020 ◽

Author(s):

Yanjin Wang ◽

Pei Wang ◽

Shudao Zhang ◽

Hao Pan

Keyword(s):

Turning Point ◽

Clinical Symptoms ◽

Transmission Rate ◽

Basic Reproductive Number ◽

Reproductive Number ◽

The Novel ◽

Wuhan City ◽

Start Date ◽

Rapid Spread ◽

Novel Coronavirus

Abstract Motivated by the quick control in Wuhan, China, and the rapid spread in other countries of COVID-19, we investigate the questions that what is the turning point in Wuhan by quantifying the variety of basic reproductive number after the lockdown city. The answer may help the world to control the COVID-19 epidemic. A modified SEIR model is used to study the COVID-19 epidemic in Wuhan city. Our model is calibrated by the hospitalized cases. The modeling result gives out that the means of basic reproductive numbers are 1.5517 (95% CI 1.1716-4.4283) for the period from Jan 25 to Feb 11, 2020, and 0.4738(95% CI 0.0997-0.8370) for the period from Feb 12 to Mar 10. The transmission rate fell after Feb 12, 2020 as a result of China’s COVID-19 strategy of keeping society distance and the medical support from all China, but principally because of the clinical symptoms to be used for the novel coronavirus pneumonia (NCP) confirmation in Wuhan since Feb 12, 2020. Clinical diagnosis can quicken up NCP-confirmation such that the COVID-19 patients can be isolated without delay. So the clinical symptoms pneumonia-confirmation is the turning point of the COVID-19 battle of Wuhan. The measure of clinical symptoms pneumonia-confirmation in Wuhan has delayed the growth and reduced size of the COVID-19 epidemic, decreased the peak number of the hospitalized cases by 96% in Wuhan. Our modeling also indicates that the earliest start date of COVID-19 in Wuhan may be Nov 2, 2019.

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Variation in SARS-CoV-2 free-living survival and environmental transmission can modulate the intensity of COVID-19 outbreaks

10.1101/2020.05.04.20090092 ◽

2020 ◽

Cited By ~ 2

Author(s):

C. Brandon Ogbunugafor ◽

Miles Miller-Dickson ◽

Victor A. Meszaros ◽

Lourdes M. Gomez ◽

Anarina L. Murillo ◽

...

Keyword(s):

Basic Reproductive Number ◽

Reproductive Number ◽

Disease Dynamics ◽

Free Living ◽

Environmental Transmission ◽

Country Level ◽

History Of ◽

Virus Survival ◽

Case Data

ABSTRACTCOVID-19 has circled the globe, rapidly expanding into a pandemic within a matter of weeks. While early studies revealed important features of SARS-CoV-2 transmission, the role of variation in free-living virus survival in modulating the dynamics of outbreaks remains unclear and controversial. Using an empirically determined understanding of the natural history of SARS-CoV-2 infection and detailed, country-level case data, we elucidate how variation in free-living virus survival influences key features of COVID-19 epidemics. Our findings suggest that environmental transmission can have a subtle, yet significant influence on COVID-19’s basic reproductive number () and other key signatures of outbreak intensity. Summarizing, we propose that variation in environmental transmission may explain some observed differences in disease dynamics from setting to setting, and can inform public health interventions.

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An artificially simulated outbreak of a respiratory infectious disease

10.21203/rs.2.14142/v7 ◽

2020 ◽

Author(s):

Zuiyuan Guo ◽

Shuang Xu ◽

Libo Tong ◽

Botao Dai ◽

Yuandong Liu ◽

...

Keyword(s):

Infectious Disease ◽

Infectious Diseases ◽

Attack Rate ◽

General Pattern ◽

Basic Reproductive Number ◽

Reproductive Number ◽

Developmental Trend ◽

Collision Model ◽

Military Camp ◽

Epidemiological Characteristics

Abstract Background Outbreaks of respiratory infectious diseases often occur in crowded places. To understand the pattern of spread of an outbreak of a respiratory infectious disease and provide a theoretical basis for targeted implementation of scientific prevention and control, we attempted to establish a stochastic model to simulate an outbreak of a respiratory infectious disease at a military camp. This model fits the general pattern of disease transmission and further enriches theories on the transmission dynamics of infectious diseases. Methods We established an enclosed system of 500 people exposed to adenovirus type 7 (ADV 7) in a military camp. During the infection period, the patients transmitted the virus randomly to susceptible people. The spread of the epidemic under militarized management mode was simulated using a computer model named “the random collision model”, and the effects of factors such as the basic reproductive number ( R 0 ), time of isolation of the patients (TOI), interval between onset and isolation (IOI), and immunization rates (IR) on the developmental trend of the epidemic were quantitatively analysed. Results Once the R 0 exceeded 1.5, the median attack rate increased sharply; when R 0 =3, with a delay in the TOI, the attack rate increased gradually and eventually remained stable. When the IOI exceeded 2.3 days, the median attack rate also increased dramatically. When the IR exceeded 0.5, the median attack rate approached zero. The median generation time was 8.26 days, (95% confidence interval [CI]: 7.84-8.69 days). The partial rank correlation coefficients between the attack rate of the epidemic and R 0 , TOI, IOI, and IR were 0.61, 0.17, 0.45, and -0.27, respectively. Conclusions The random collision model not only simulates how an epidemic spreads with superior precision but also allows greater flexibility in setting the activities of the exposure population and different types of infectious diseases, which is conducive to furthering exploration of the epidemiological characteristics of epidemic outbreaks.

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A New Features of SARS-CoV-2 Infection in Wenzhou, China

10.21203/rs.2.23945/v1 ◽

2020 ◽

Author(s):

Zhao Hongjun ◽

Xiaoxiao Lu ◽

Tiegang Li ◽

Boqi Rao ◽

Dedong Wang ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Clinical Characteristics ◽

Cross Sectional Study ◽

Sectional Study ◽

Wuhan City ◽

Intimate Contact ◽

Cross Sectional ◽

Epidemic Area ◽

History Of ◽

Epidemiological Characteristics

Abstract BACKGROUND: An outbreak of pneumonia associated with the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) was initially emerged in Wuhan city, and subsequently spread throughout China. Then the epidemic is rapidly circulating in a few other countries at present. So it is very urgent to delineate the clinical characteristics of these affected patients. METHODS: To investigate the epidemiological characteristics of this new Coronavirus Disease 2019 (COVID-19), a cross-sectional study was executed with 459 patients with confirmed COVID-19 in Wenzhou, China, from January 27 to February 12, 2020. RESULTS: The median age of all patients was 48.0 years, and 46.8% were females. 37.5% of patients had a history of residence in Wuhan. Fever (72.1%) and cough (43.6%) were the most frequent symptoms. We also found that there were three kinds of unconventional patients including 4.4% of total confirmed patients who were asymptomatic, 7.8% patients who had no link to Wuhan city but contact with individuals from Wuhan without any symptoms at the time of contact, and 10.7% who had no link to Wuhan city nor a history of intimate contact with patients or individuals from Wuhan without any symptoms, respectively. CONCLUSIONS: Our findings presented the possibility of asymptomatic carriers affected with SARS-CoV-2, and this phenomenon suggested that chances of uncontrollable transmission in the larger population might be higher than formerly estimated, and transmission by these three kinds of unconventional patients in Wenzhou may be one of the characteristics of infection in other Chinese cities outside the Wuhan epidemic area.

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