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1.
JAMA Netw Open ; 5(8): e2228008, 2022 08 01.
Article in English | MEDLINE | ID: mdl-35994285

ABSTRACT

Importance: Several studies were conducted to estimate the average incubation period of COVID-19; however, the incubation period of COVID-19 caused by different SARS-CoV-2 variants is not well described. Objective: To systematically assess the incubation period of COVID-19 and the incubation periods of COVID-19 caused by different SARS-CoV-2 variants in published studies. Data Sources: PubMed, EMBASE, and ScienceDirect were searched between December 1, 2019, and February 10, 2022. Study Selection: Original studies of the incubation period of COVID-19, defined as the time from infection to the onset of signs and symptoms. Data Extraction and Synthesis: Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline, 3 reviewers independently extracted the data from the eligible studies in March 2022. The parameters, or sufficient information to facilitate calculation of those values, were derived from random-effects meta-analysis. Main Outcomes and Measures: The mean estimate of the incubation period and different SARS-CoV-2 strains. Results: A total of 142 studies with 8112 patients were included. The pooled incubation period was 6.57 days (95% CI, 6.26-6.88) and ranged from 1.80 to 18.87 days. The incubation period of COVID-19 caused by the Alpha, Beta, Delta, and Omicron variants were reported in 1 study (with 6374 patients), 1 study (10 patients), 6 studies (2368 patients) and 5 studies (829 patients), respectively. The mean incubation period of COVID-19 was 5.00 days (95% CI, 4.94-5.06 days) for cases caused by the Alpha variant, 4.50 days (95% CI, 1.83-7.17 days) for the Beta variant, 4.41 days (95% CI, 3.76-5.05 days) for the Delta variant, and 3.42 days (95% CI, 2.88-3.96 days) for the Omicron variant. The mean incubation was 7.43 days (95% CI, 5.75-9.11 days) among older patients (ie, aged over 60 years old), 8.82 days (95% CI, 8.19-9.45 days) among infected children (ages 18 years or younger), 6.99 days (95% CI, 6.07-7.92 days) among patients with nonsevere illness, and 6.69 days (95% CI, 4.53-8.85 days) among patients with severe illness. Conclusions and Relevance: The findings of this study suggest that SARS-CoV-2 has evolved and mutated continuously throughout the COVID-19 pandemic, producing variants with different enhanced transmission and virulence. Identifying the incubation period of different variants is a key factor in determining the isolation period.


Subject(s)
COVID-19 , SARS-CoV-2 , Adolescent , Aged , COVID-19/epidemiology , Child , Humans , Infectious Disease Incubation Period , Middle Aged , Pandemics
2.
Emerg Infect Dis ; 28(10): 2078-2081, 2022 Oct.
Article in English | MEDLINE | ID: mdl-35994726

ABSTRACT

We analyzed the first 255 PCR-confirmed cases of monkeypox in Italy in 2022. Preliminary estimates indicate mean incubation period of 9.1 (95% CI 6.5-10.9) days, mean generation time of 12.5 (95% CI 7.5-17.3) days, and reproduction number among men who have sex with men of 2.43 (95% CI 1.82-3.26).


Subject(s)
Monkeypox , Sexual and Gender Minorities , Homosexuality, Male , Humans , Infectious Disease Incubation Period , Italy/epidemiology , Male , Monkeypox virus , Reproduction
3.
Front Public Health ; 10: 905020, 2022.
Article in English | MEDLINE | ID: mdl-35968429

ABSTRACT

Background: The incubation period of the coronavirus disease 2019 (COVID-19) is estimated to vary by demographic factors and the COVID-19 epidemic periods. Objective: This study examined the incubation period of the wild type of SARS-CoV-2 infections by the different age groups, gender, and epidemic periods in South Korea. Methods: We collected COVID-19 patient data from the Korean public health authorities and estimated the incubation period by fitting three different distributions, including log-normal, gamma, and Weibull distributions, after stratification by gender and age groups. To identify any temporal impact on the incubation period, we divided the study period into two different epidemic periods (Period-1: 19 January-19 April 2020 and Period-2: 20 April-16 October 2020), and assessed for any differences. Results: We identified the log-normal as the best-fit model. The estimated median incubation period was 4.6 (95% CI: 3.9-4.9) days, and the 95th percentile was 11.7 (95% CI: 10.2-12.2) days. We found that the incubation period did not differ significantly between males and females (p = 0.42), age groups (p = 0.60), and the two different epidemic periods (p = 0.77). Conclusions: The incubation period of wild type of SARS-CoV-2 infection during the COVID-19 pandemic 2020, in South Korea, does not likely differ by age group, gender and epidemic period.


Subject(s)
COVID-19 , COVID-19/epidemiology , Female , Humans , Infectious Disease Incubation Period , Male , Pandemics , Republic of Korea/epidemiology , SARS-CoV-2
4.
Multimedia | Multimedia Resources | ID: multimedia-9779

ABSTRACT

O vídeo apresenta informações sobre o que caracteriza um período de incubação de uma doença. No caso do novo coronavírus, o período de incubação é de duas semanas. O aplicativo FioLibras é um projeto do Instituto de Comunicação e Informação Científica e Tecnológica em Saúde da Fundação Oswaldo Cruz (Icict/Fiocruz), em parceria com o Núcleo de Estudos em Diversidade e Inclusão de Surdos da Universidade Federal Fluminense (Nuedis/UFF), e conta com financiamento do Fundo de Inovação da Fiocruz e do Ministério da Saúde, por meio do Programa Fiocruz de Fomento à Inovação (Inova Fiocruz).


Subject(s)
Infectious Disease Incubation Period , Coronavirus Infections , Information Dissemination , Sign Language , e-Accessibility
5.
BMJ Case Rep ; 15(7)2022 Jul 05.
Article in English | MEDLINE | ID: mdl-35790324

ABSTRACT

Leprosy is a chronic granulomatous infection predominantly involving the skin and peripheral nervous system. The condition is caused by infection with the obligate intracellular bacillus Mycobacterium leprae and the clinical phenotype is largely dependent on the host immune response to the organism. Transmission is suspected to occur via respiratory secretions with infection usually requiring prolonged periods of contact. The incubation period is highly variable with disease manifestations appearing up to several decades after the initial exposure. The disease can be broadly divided into 'paucibacillary' and 'multibacillary', and treatment with multidrug therapy including dapsone, clofazimine and rifampicin offers high rates of cure. Here, we report of a case of leprosy with a suspected incubation period in excess of 50 years following occupational exposure in rural Australia. To our knowledge, this incubation period is the longest reported to date.


Subject(s)
Leprosy, Multibacillary , Leprosy , Drug Therapy, Combination , Humans , Infectious Disease Incubation Period , Leprostatic Agents/therapeutic use , Leprosy/drug therapy , Leprosy, Multibacillary/diagnosis , Leprosy, Multibacillary/drug therapy , Mycobacterium leprae
6.
Euro Surveill ; 27(24)2022 06.
Article in English | MEDLINE | ID: mdl-35713026

ABSTRACT

In May 2022, monkeypox outbreaks have been reported in countries not endemic for monkeypox. We estimated the monkeypox incubation period, using reported exposure and symptom-onset times for 18 cases detected and confirmed in the Netherlands up to 31 May 2022. Mean incubation period was 8.5 days (5th-95th percentiles: 4.2-17.3), underpinning the current recommendation to monitor or isolate/quarantine case contacts for 21 days. However, as the incubation period may differ between different transmission routes, further epidemiological investigations are needed.


Subject(s)
Disease Outbreaks , Monkeypox , Humans , Infectious Disease Incubation Period , Monkeypox/diagnosis , Monkeypox/epidemiology , Monkeypox virus , Netherlands/epidemiology
7.
J Math Biol ; 84(6): 53, 2022 05 09.
Article in English | MEDLINE | ID: mdl-35532851

ABSTRACT

This paper establishes the global attractivity of a positive constant equilibrium of a nonlocal and time-delayed diffusive malaria model in a homogeneous case. The same problem was achieved in a recent paper (Lou and Zhao in J Math Biol 62:543-568, 2011) by using the fluctuation method, but with a sufficient condition that the disease will become stable requires a sufficiently large basic reproduction number [Formula: see text]. The present study is devoted to remove the sufficient condition by utilizing an appropriate Lyapunov functional and shows that the disease will become stable when [Formula: see text] is exactly greater than one, which remarkably improves the known results in Lou and Zhao (2011).


Subject(s)
Malaria , Models, Biological , Animals , Basic Reproduction Number , Computer Simulation , Infectious Disease Incubation Period , Mosquito Vectors
8.
Article in English | MEDLINE | ID: mdl-35627870

ABSTRACT

We aimed to elucidate the range of the incubation period in patients infected with the SARS-CoV-2 Omicron variant in comparison with the Alpha variant. Contact tracing data from three Japanese public health centers (total residents, 1.06 million) collected following the guidelines of the Infectious Diseases Control Law were reviewed for 1589 PCR-confirmed COVID-19 cases diagnosed in January 2022. We identified 77 eligible symptomatic patients for whom the date and setting of transmission were known, in the absence of any other probable routes of transmission. The observed incubation period was 3.03 ± 1.35 days (mean ± SDM). In the log-normal distribution, 5th, 50th and 95th percentile values were 1.3 days (95% CI: 1.0-1.6), 2.8 days (2.5-3.1) and 5.8 days (4.8-7.5), significantly shorter than among the 51 patients with the Alpha variant diagnosed in April and May in 2021 (4.94 days ± 2.19, 2.1 days (1.5-2.7), 4.5 days (4.0-5.1) and 9.6 days (7.4-13.0), p < 0.001). As this incubation period, mainly of sublineage BA.1, is even shorter than that in the Delta variant, it is thought to partially explain the variant replacement occurring in late 2021 to early 2022 in many countries.


Subject(s)
COVID-19 , Infectious Disease Incubation Period , SARS-CoV-2 , COVID-19/epidemiology , Contact Tracing , Humans , Japan/epidemiology , SARS-CoV-2/genetics , SARS-CoV-2/physiology
9.
BMC Pulm Med ; 22(1): 188, 2022 May 12.
Article in English | MEDLINE | ID: mdl-35549897

ABSTRACT

BACKGROUND: Most severe, critical, or mortal COVID-19 cases often had a relatively stable period before their status worsened. We developed a deterioration risk model of COVID-19 (DRM-COVID-19) to predict exacerbation risk and optimize disease management on admission. METHOD: We conducted a multicenter retrospective cohort study with 239 confirmed symptomatic COVID-19 patients. A combination of the least absolute shrinkage and selection operator (LASSO), change-in-estimate (CIE) screened out independent risk factors for the multivariate logistic regression model (DRM-COVID-19) from 44 variables, including epidemiological, demographic, clinical, and lung CT features. The compound study endpoint was progression to severe, critical, or mortal status. Additionally, the model's performance was evaluated for discrimination, accuracy, calibration, and clinical utility, through internal validation using bootstrap resampling (1000 times). We used a nomogram and a network platform for model visualization. RESULTS: In the cohort study, 62 cases reached the compound endpoint, including 42 severe, 18 critical, and two mortal cases. DRM-COVID-19 included six factors: dyspnea [odds ratio (OR) 4.89;confidence interval (95% CI) 1.53-15.80], incubation period (OR 0.83; 95% CI 0.68-0.99), number of comorbidities (OR 1.76; 95% CI 1.03-3.05), D-dimer (OR 7.05; 95% CI, 1.35-45.7), C-reactive protein (OR 1.06; 95% CI 1.02-1.1), and semi-quantitative CT score (OR 1.50; 95% CI 1.27-1.82). The model showed good fitting (Hosmer-Lemeshow goodness, X2(8) = 7.0194, P = 0.53), high discrimination (the area under the receiver operating characteristic curve, AUROC, 0.971; 95% CI, 0.949-0.992), precision (Brier score = 0.051) as well as excellent calibration and clinical benefits. The precision-recall (PR) curve showed excellent classification performance of the model (AUCPR = 0.934). We prepared a nomogram and a freely available online prediction platform ( https://deterioration-risk-model-of-covid-19.shinyapps.io/DRMapp/ ). CONCLUSION: We developed a predictive model, which includes the including incubation period along with clinical and lung CT features. The model presented satisfactory prediction and discrimination performance for COVID-19 patients who might progress from mild or moderate to severe or critical on admission, improving the clinical prognosis and optimizing the medical resources.


Subject(s)
COVID-19 , COVID-19/diagnostic imaging , Cohort Studies , Humans , Infectious Disease Incubation Period , Lung/diagnostic imaging , Retrospective Studies , Tomography, X-Ray Computed
11.
Emerg Infect Dis ; 28(6): 1224-1228, 2022 06.
Article in English | MEDLINE | ID: mdl-35393009

ABSTRACT

Contact tracing data of SARS-CoV-2 Omicron variant cases during December 2021 in Cantabria, Spain, showed increased transmission (secondary attack rate 39%) compared with Delta cases (secondary attack rate 26%), uninfluenced by vaccination status. Incubation and serial interval periods were also reduced. Half of Omicron transmissions happened before symptom onset in the index case-patient.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , Humans , Incidence , Infectious Disease Incubation Period , Spain/epidemiology
12.
Emerg Infect Dis ; 28(4): 793-801, 2022 04.
Article in English | MEDLINE | ID: mdl-35318913

ABSTRACT

Chronic wasting disease (CWD) is a naturally-occurring neurodegenerative disease of cervids. Raccoons (Procyon lotor) and meadow voles (Microtus pennsylvanicus) have previously been shown to be susceptible to the CWD agent. To investigate the potential for transmission of the agent of CWD from white-tailed deer to voles and subsequently to raccoons, we intracranially inoculated raccoons with brain homogenate from a CWD-affected white-tailed deer (CWDWtd) or derivatives of this isolate after it had been passaged through voles 1 or 5 times. We found that passage of the CWDWtd isolate through voles led to a change in the biologic behavior of the CWD agent, including increased attack rates and decreased incubation periods in raccoons. A better understanding of the dynamics of cross-species transmission of CWD prions can provide insights into how these infectious proteins evolve in new hosts.


Subject(s)
Deer , Neurodegenerative Diseases , Wasting Disease, Chronic , Animals , Arvicolinae , Incidence , Infectious Disease Incubation Period , Raccoons , Wasting Disease, Chronic/epidemiology
13.
Article in English | MEDLINE | ID: mdl-35162151

ABSTRACT

Few studies have assessed incubation periods of the severe acute respiratory syndrome coronavirus 2 Delta variant. This study aimed to elucidate the transmission dynamics, especially the incubation period, for the Delta variant compared with non-Delta strains. We studied unvaccinated coronavirus disease 2019 patients with definite single exposure date from August 2020 to September 2021 in Japan. The incubation periods were calculated and compared by Mann-Whitney U test for Delta (with L452R mutation) and non-Delta cases. We estimated mean and percentiles of incubation period by fitting parametric distribution to data in the Bayesian statistical framework. We enrolled 214 patients (121 Delta and 103 non-Delta cases) with one specific date of exposure to the virus. The mean incubation period was 3.7 days and 4.9 days for Delta and non-Delta cases, respectively (p-value = 0.000). When lognormal distributions were fitted, the estimated mean incubation periods were 3.7 (95% credible interval (CI) 3.4-4.0) and 5.0 (95% CI 4.5-5.6) days for Delta and non-Delta cases, respectively. The estimated 97.5th percentile of incubation period was 6.9 (95% CI 5.9-8.0) days and 10.4 (95% CI 8.6-12.7) days for Delta and non-Delta cases, respectively. Unvaccinated Delta variant cases had shorter incubation periods than non-Delta variant cases.


Subject(s)
COVID-19 , Infectious Disease Incubation Period , Bayes Theorem , Humans , Japan/epidemiology , SARS-CoV-2 , Vaccination/statistics & numerical data
15.
Int J Environ Health Res ; 32(8): 1707-1715, 2022 Aug.
Article in English | MEDLINE | ID: mdl-33818217

ABSTRACT

The COVID-19 pandemic has been causing serious disasters to mankind. The incubation period is a key parameter for epidemic control and also an important basis for epidemic prediction, but its distribution law remains unclear. This paper analyzed the epidemiological information of 787 confirmed non-Wuhan resident cases, and systematically studied the characteristics of the incubation period of COVID-19 based on the interval-censored data estimation method. The results show that the incubation period of COVID-19 approximately conforms to the Gamma distribution with a mean value of 7.8 (95%CI:7.4-8.5) days and a median value of 7.0 (95%CI:6.7-7.3) days. The incubation period was positively correlated with age and negatively correlated with disease severity. Female cases presented a slightly higher incubation period than that of males. The proportion of infected persons who developed symptoms within 14 days was 91.6%. These results are of great significance to the prevention and control of the COVID-19 pandemic.


Subject(s)
COVID-19 , China/epidemiology , Female , Humans , Infectious Disease Incubation Period , Male , Pandemics
16.
BMC Med ; 19(1): 308, 2021 12 07.
Article in English | MEDLINE | ID: mdl-34872559

ABSTRACT

BACKGROUND: From 2 January to 14 February 2021, a local outbreak of COVID-19 occurred in Shijiazhuang, the capital city of Hebei Province, with a population of 10 million. We analyzed the characteristics of the local outbreak of COVID-19 in Shijiazhuang and evaluated the effects of serial interventions. METHODS: Publicly available data, which included age, sex, date of diagnosis, and other patient information, were used to analyze the epidemiological characteristics of the COVID-19 outbreak in Shijiazhuang. The maximum likelihood method and Hamiltonian Monte Carlo method were used to estimate the serial interval and incubation period, respectively. The impact of incubation period and different interventions were simulated using a well-fitted SEIR+q model. RESULTS: From 2 January to 14 February 2021, there were 869 patients with symptomatic COVID-19 in Shijiazhuang, and most cases (89.6%) were confirmed before 20 January. Overall, 40.2% of the cases were male, 16.3% were aged 0 to 19 years, and 21.9% were initially diagnosed as asymptomatic but then became symptomatic. The estimated incubation period was 11.6 days (95% CI 10.6, 12.7 days) and the estimated serial interval was 6.6 days (0.025th, 0.975th: 0.6, 20.0 days). The results of the SEIR+q model indicated that a longer incubation period led to a longer epidemic period. If the comprehensive quarantine measures were reduced by 10%, then the nucleic acid testing would need to increase by 20% or more to minimize the cumulative number of cases. CONCLUSIONS: Incubation period was longer than serial interval suggested that more secondary transmission may occur before symptoms onset. The long incubation period made it necessary to extend the isolation period to control the outbreak. Timely contact tracing and implementation of a centralized quarantine quickly contained this epidemic in Shijiazhuang. Large-scale nucleic acid testing also helped to identify cases and reduce virus transmission.


Subject(s)
COVID-19 , Infectious Disease Incubation Period , Quarantine , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/epidemiology , Child , Child, Preschool , China/epidemiology , Disease Outbreaks , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Models, Theoretical , SARS-CoV-2 , Young Adult
17.
BMC Public Health ; 21(1): 2239, 2021 12 09.
Article in English | MEDLINE | ID: mdl-34886835

ABSTRACT

BACKGROUND: COVID-19 patients with long incubation period were reported in clinical practice and tracing of close contacts, but their epidemiological or clinical features remained vague. METHODS: We analyzed 11,425 COVID-19 cases reported between January-August, 2020 in China. The accelerated failure time model, Logistic and modified Poisson regression models were used to investigate the determinants of prolonged incubation period, as well as their association with clinical severity and transmissibility, respectively. RESULT: Among local cases, 268 (10.2%) had a prolonged incubation period of > 14 days, which was more frequently seen among elderly patients, those residing in South China, with disease onset after Level I response measures administration, or being exposed in public places. Patients with prolonged incubation period had lower risk of severe illness (ORadjusted = 0.386, 95% CI: 0.203-0.677). A reduced transmissibility was observed for the primary patients with prolonged incubation period (50.4, 95% CI: 32.3-78.6%) than those with an incubation period of ≤14 days. CONCLUSIONS: The study provides evidence supporting a prolonged incubation period that exceeded 2 weeks in over 10% for COVID-19. Longer monitoring periods than 14 days for quarantine or persons potentially exposed to SARS-CoV-2 should be justified in extreme cases, especially for those elderly.


Subject(s)
COVID-19 , Epidemics , Infectious Disease Incubation Period , COVID-19/epidemiology , China/epidemiology , Humans , Quarantine , SARS-CoV-2
18.
J Gen Virol ; 102(12)2021 12.
Article in English | MEDLINE | ID: mdl-34904943

ABSTRACT

Prion diseases are fatal and infectious neurodegenerative diseases in humans and other mammals caused by templated misfolding of the endogenous prion protein (PrP). Although there is currently no vaccine or therapy against prion disease, several classes of small-molecule compounds have been shown to increase disease-free incubation time in prion-infected mice. An apparent obstacle to effective anti-prion therapy is the emergence of drug-resistant strains during static therapy with either single compounds or multi-drug combination regimens. Here, we treated scrapie-infected mice with dynamic regimens that alternate between different classes of anti-prion drugs. The results show that alternating regimens containing various combinations of Anle138b, IND24 and IND116135 reduce the incidence of combination drug resistance, but do not significantly increase long-term disease-free survival compared to monotherapy. Furthermore, the alternating regimens induced regional vacuolation profiles resembling those generated by a single component of the alternating regimen, suggesting the emergence of strain dominance.


Subject(s)
Drug Resistance/drug effects , Prions/antagonists & inhibitors , Scrapie/drug therapy , Animals , Brain/pathology , Disease Models, Animal , Disease-Free Survival , Drug Therapy, Combination , Infectious Disease Incubation Period , Mice , Prions/drug effects , Scrapie/mortality , Scrapie/pathology
19.
Emerg Infect Dis ; 27(12): 3147-3150, 2021 12.
Article in English | MEDLINE | ID: mdl-34808074

ABSTRACT

Toscana virus (TOSV) is an emerging pathogen in the Mediterranean area and is neuroinvasive in its most severe form. Basic knowledge on TOSV biology is limited. We conducted a systematic review on travel-related infections to estimate the TOSV incubation period. We estimated the incubation period at 12.1 days.


Subject(s)
Bunyaviridae Infections , Infectious Disease Incubation Period , Sandfly fever Naples virus , Virus Diseases , Antibodies, Viral , Bunyaviridae Infections/epidemiology , Humans , Sandfly fever Naples virus/genetics , Travel , Travel-Related Illness
20.
Western Pac Surveill Response J ; 12(2): 65-81, 2021.
Article in English | MEDLINE | ID: mdl-34540315

ABSTRACT

BACKGROUND: The emergence of a new pathogen requires a rapid assessment of its transmissibility, to inform appropriate public health interventions. METHODS: The peer-reviewed literature published between 1 January and 30 April 2020 on COVID-19 in PubMed was searched. Estimates of the incubation period, serial interval and reproduction number for COVID-19 were obtained and compared. RESULTS: A total of 86 studies met the inclusion criteria. Of these, 33 estimated the mean incubation period (4-7 days) and 15 included estimates of the serial interval (mean 4-8 days; median length 4-5 days). Fifty-two studies estimated the reproduction number. Although reproduction number estimates ranged from 0.3 to 14.8, in 33 studies (63%), they fell between 2 and 3. DISCUSSION: Studies calculating the incubation period and effective reproduction number were published from the beginning of the pandemic until the end of the study period (30 April 2020); however, most of the studies calculating the serial interval were published in April 2020. The calculated incubation period was similar over the study period and in different settings, whereas estimates of the serial interval and effective reproduction number were setting-specific. Estimates of the serial interval were shorter at the end of the study period as increasing evidence of pre-symptomatic transmission was documented and as jurisdictions enacted outbreak control measures. Estimates of the effective reproduction number varied with the setting and the underlying model assumptions. Early analysis of epidemic parameters provides vital information to inform the outbreak response.


Subject(s)
COVID-19/epidemiology , Basic Reproduction Number , Disease Outbreaks , Humans , Infectious Disease Incubation Period , Pandemics , SARS-CoV-2
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