scholarly journals Computing a Lower Bound for the Total Size of the COVID-19 Infected Population Iceberg Using the General Age-Group Distribution

Author(s):  
Yuval Shahar ◽  
Osnat Mokryn

The COVID-19 pandemic has raised questions regarding the total prevalence of infection, referred to as the (Infection) Iceberg. Accurate estimates of country-specific Iceberg sizes support better pandemic monitoring, evaluation of proximity to herd immunity, estimation of infection fatality rates (IFRs), and assessment of risks due to infection by asymptomatic individuals. Previous suggestions included surveying the population for COVID-19 symptoms, and a few countries performed randomized serological testing. We suggest a new method for setting a lower bound on the Iceberg size, by finding the Pivot group, the population sub-group with the highest relative risk for being confirmed as positively infected in the RT-PCR test. We differentiate between susceptibility to infection, which we assume to be uniform across all population sub-groups, and susceptibility to developing symptoms and complications, which may differ between sub-group. Our key assumption is that the Pivot sub-group's proportion within the infected Iceberg is similar to its proportion within the population (or even lower). We compute the minimal Iceberg Factor that allows for a sufficient number of people from the Pivot sub-group within the presumed Iceberg to explain the portion of the Pivot group that is confirmed positive, and also the minimal Iceberg Factor when allowing for a statistically insignificant deviation from the population's Pivot group proportion. We demonstrate, using the UK and Spain serological surveys, that our key assumption holds, and that the actual Iceberg factors fit our predictions. We compute minimal Iceberg factors, and when possible, assessed IFRs and serology-based IFRs, for nine countries.

Author(s):  
Sebastián Videla ◽  
Aurema Otero ◽  
Sara Martí ◽  
M. Ángeles Domínguez ◽  
Nuria Fabrellas ◽  
...  

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in December 2019 and still is a major global health challenge. Lockdown measures and social distancing sparked a global shift towards online learning, which deeply impacted universities’ daily life, and the University of Barcelona (UB) was not an exception. Accordingly, we aimed to determine the impact of the SARS-CoV-2 pandemic at the UB. To that end, we performed a cross-sectional study on a sample of 2784 UB members (n = 52,529). Participants answered a brief, ad hoc, online epidemiological questionnaire and provided a nasal swab for reverse transcription polymerase chain reaction (RT-PCR) SARS-CoV-2 analysis and a venous blood sample for SARS-CoV-2 IgG antibody assay. Total prevalence of SARS-CoV-2 infection (positive RT-PCR or positive IgG) was 14.9% (95%CI 13.3 to 17.0%). Forty-four participants (1.6%, 95%CI: 1.2–2.1%) were positive for SARS-CoV-2 RT-PCR. IgG against SARS-CoV-2 was observed in 12.8% (95%CI: 11.6–14.1%) of participants. Overall, while waiting for population vaccination and/or increased herd immunity, we should concentrate on identifying and isolating new cases and their contacts.


2021 ◽  
Author(s):  
Grace Hsiao-Hsuan Jen ◽  
Amy Ming-Fang Yen ◽  
Cheng-Yang Hsu ◽  
Harold Sjursen ◽  
Sam Li-Sheng Chen ◽  
...  

BACKGROUND Pre-symptomatic imported COVID-19 cases play an important role in border control strategies for containing their further spread to community outbreaks. OBJECTIVE A pre-symptomatic incubation model was proposed to develop precision screening, quarantine, and isolation strategies for containing imported COVID-19 case. METHODS The natural history model of pre-symptomatic and symptomatic COVID-19 was constructed by using 727 imported cases of COVID-19 in Taiwan, consisting of the first pandemic period (March-June), the second containment period (July-September), and the third pandemic period (October-December) in parallel with the evolution of new virus variants. We collected the valuable information on symptomatic cases ascertained upon the arrival and the natural transition from pre-symptomatic RT-PCR detectable phase (RT-PCRDP) to symptomatic phase during 14-day quarantine period. We estimated the incidence of pre-symptomatic disease and the dwelling time from pre-symptomatic RT-PCRDP to symptomatic phase on which we were based to simulate various strategies of screening with RT-PCR test and the optimal interval of quarantine and isolation for the vaccinated and unvaccinated travelers. RESULTS The overall daily rate (per 100,000) of pre-symptomatic COVID-19 cases was 106 (95% CI: 95-118) in the first period (March-June), fell to 37 (95% CI: 27.9-47.2) in the second period (July-September), and resurged to 141 (95% CI: 117-164) in the third period (October-December). Given the median dwelling time, over 82% of the transition from pre-symptomatic to symptomatic phase were noted in 5-day quarantine. The length of quarantine given two tests can be reduced from 14 to 5 days for the unvaccinated traveler. It can be precisely determined by the classification of country-specific risk and may be reduced to two days or lifting, depending on country-specific risk, after vaccination. CONCLUSIONS Precision strategies for imported COVID-19 cases provide a solution to the trade-off between border control and re-opening to travel before vaccination to reach herd immunity worldwide.


1998 ◽  
Vol 38 (12) ◽  
pp. 51-56 ◽  
Author(s):  
K. Henshilwood ◽  
J. Green ◽  
D. N. Lees

This study investigates human enteric virus contamination of a shellfish harvesting area. Samples were analysed over a 14-month period for Small Round Structured Viruses (SRSVs) using a previously developed nested RT-PCR. A clear seasonal difference was observed with the largest numbers of positive samples obtained during the winter period (October to March). This data concurs with the known winter association of gastroenteric illness due to oyster consumption in the UK and also with the majority of the outbreaks associated with shellfish harvested from this area during the study period. RT-PCR positive amplicons were further characterised by cloning and sequencing. Sequence analysis of the positive samples identified eleven SRSV strains, of both Genogroup I and Genogroup II, occurring throughout the study period. Many shellfish samples contained a mixture of strains with a few samples containing up to three different strains with both Genogroups represented. The observed common occurrence of strain mixtures may have implications for the role of shellfish as a vector for dissemination of SRSV strains. These results show that nested RT-PCR can identify SRSV contamination in shellfish harvesting areas. Virus monitoring of shellfish harvesting areas by specialist laboratories using RT-PCR is a possible approach to combating the transmission of SRSVs by molluscan shellfish and could potentially offer significantly enhanced levels of public health protection.


Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 550
Author(s):  
Peter A. C. Maple

In the UK, population virus or antibody testing using virus swabs, serum samples, blood spots or oral fluids has been performed to a limited extent for several diseases including measles, mumps, rubella and hepatitis and HIV. The collection of population-based infection and immunity data is key to the monitoring of disease prevalence and assessing the effectiveness of interventions such as behavioural modifications and vaccination. In particular, the biological properties of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its interaction with the human host have presented several challenges towards the development of population-based immunity testing. Measuring SARS-CoV-2 immunity requires the development of antibody assays of acceptable sensitivity and specificity which are capable of accurately detecting seroprevalence and differentiating protection from non-protective responses. Now that anti-COVID-19 vaccines are becoming available there is a pressing need to measure vaccine efficacy and the development of herd immunity. The unprecedented impact of the SARS-CoV-2 pandemic in the UK in terms of morbidity, mortality, and economic and social disruption has mobilized a national scientific effort to learn more about this virus. In this article, the challenges of testing for SARS-CoV-2 infection, particularly in relation to population-based immunity testing, will be considered and examples given of relevant national level studies.


2021 ◽  
Vol 8 (7) ◽  
pp. 117
Author(s):  
Giovanni Cilia ◽  
Laura Zavatta ◽  
Rosa Ranalli ◽  
Antonio Nanetti ◽  
Laura Bortolotti

The deformed wing virus (DWV) is one of the most common honey bee pathogens. The virus may also be detected in other insect species, including Bombus terrestris adults from wild and managed colonies. In this study, individuals of all stages, castes, and sexes were sampled from three commercial colonies exhibiting the presence of deformed workers and analysed for the presence of DWV. Adults (deformed individuals, gynes, workers, males) had their head exscinded from the rest of the body and the two parts were analysed separately by RT-PCR. Juvenile stages (pupae, larvae, and eggs) were analysed undissected. All individuals tested positive for replicative DWV, but deformed adults showed a higher number of copies compared to asymptomatic individuals. Moreover, they showed viral infection in their heads. Sequence analysis indicated that the obtained DWV amplicons belonged to a strain isolated in the United Kingdom. Further studies are needed to characterize the specific DWV target organs in the bumblebees. The result of this study indicates the evidence of DWV infection in B. terrestris specimens that could cause wing deformities, suggesting a relationship between the deformities and the virus localization in the head. Further studies are needed to define if a specific organ could be a target in symptomatic bumblebees.


BMJ Open ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. e018394 ◽  
Author(s):  
Dörthe Brüggmann ◽  
Jana Kollascheck ◽  
David Quarcoo ◽  
Michael H Bendels ◽  
Doris Klingelhöfer ◽  
...  

ObjectiveAbout 2% of all pregnancies are complicated by the implantation of the zygote outside the uterine cavity and termed ectopic pregnancy. Whereas a multitude of guidelines exists and related research is constantly growing, no thorough assessment of the global research architecture has been performed yet. Hence, we aim to assess the associated scientific activities in relation to geographical and chronological developments, existing research networks and socioeconomic parameters.DesignRetrospective, descriptive study.SettingOn the basis of the NewQIS platform, scientometric methods were combined with novel visualising techniques such as density-equalising mapping to assess the scientific output on ectopic pregnancy. Using the Web of Science, we identified all related entries from 1900 to 2012.Results8040 publications were analysed. The USA and the UK were dominating the field in regard to overall research activity (2612 and 723 publications), overall citation numbers and country-specific H-Indices (US: 80, UK: 42). Comparison to economic power of the most productive countries demonstrated that Israel invested more resources in ectopic pregnancy-related research than other nations (853.41 ectopic pregnancy-specific publications per 1000 billlion US$ gross domestic product (GDP)), followed by the UK (269.97). Relation to the GDP per capita index revealed 49.3 ectopic pregnancy-specific publications per US$1000 GDP per capita for the USA in contrast to 17.31 for the UK. Semiqualitative indices such as country-specific citation rates ranked Switzerland first (24.7 citations per ectopic pregnancy-specific publication), followed by the Scandinavian countries Finland and Sweden. Low-income countries did not exhibit significant research activities.ConclusionsThis is the first in-depth analysis of global ectopic pregnancy research since 1900. It offers unique insights into the global scientific landscape. Besides the USA and the UK, Scandinavian countries and Switzerland can also be regarded as leading nations with regard to their relative socioeconomic input.


2021 ◽  
Vol 32 (7) ◽  
pp. 282-287
Author(s):  
Alison While

Vaccine hesitancy is a concern both globally and within the UK. Alison While reviews the evidence relating to vaccine hesitancy, its underlying factors and the sociodemographic variations Vaccination is an important public health intervention, but its effectiveness depends upon the uptake of vaccination reaching sufficient levels to yield ‘herd’ immunity. While the majority of the UK hold positive attitudes about vaccination, some people, including health professionals, decline vaccinations. This article reviews the evidence relating to vaccine hesitancy, its underlying factors and the sociodemographic variations.


2020 ◽  
Vol 76 (5) ◽  
pp. 289-296 ◽  
Author(s):  
Jane L. Lynch ◽  
Margarita Barrientos-Pérez ◽  
Mona Hafez ◽  
Muhammad Yazid Jalaludin ◽  
Margarita Kovarenko ◽  
...  

<b><i>Background:</i></b> With increased awareness of type 2 diabetes (T2D) in children and adolescents, an overview of country-specific differences in epidemiology data is needed to develop a global picture of the disease development. <b><i>Summary:</i></b> This study examined country-specific prevalence and incidence data of youth-onset T2D published between 2008 and 2019, and searched for national guidelines to expand the understanding of country-specific similarities and differences. Of the 1,190 articles and 17 congress abstracts identified, 58 were included in this review. Our search found the highest reported prevalence rates of youth-onset T2D in China (520 cases/100,000 people) and the USA (212 cases/100,000) and lowest in Denmark (0.6 cases/100,000) and Ireland (1.2 cases/100,000). However, the highest incidence rates were reported in Taiwan (63 cases/100,000) and the UK (33.2 cases/100,000), with the lowest in Fiji (0.43 cases/100,000) and Austria (0.6 cases/100,000). These differences in epidemiology data may be partly explained by variations in the diagnostic criteria used within studies, screening recommendations within national guidelines and race/ethnicity within countries. <b><i>Key Messages:</i></b> Our study suggests that published country-specific epidemiology data for youth-onset T2D are varied and scant, and often with reporting inconsistencies. Finding optimal diagnostic criteria and screening strategies for this disease should be of high interest to every country. <b><i>Trial Registration:</i></b> Not applicable.


2021 ◽  
Author(s):  
Jakub Liu ◽  
Tomasz Suchocki ◽  
Joanna Szyda

Abstract One of the seminal events since 2019 has been the outbreak of the SARS-CoV-2 pandemic. Countries have adopted various policies to deal with it, but they also differ in their socio-geographical characteristics and in the public health care facilities. The aim of our study was to investigate differences between epidemiological parameters across countries. The analysed data represents SARS-CoV-2 repository provided by the Johns Hopkins University. Separately for each country we estimated recovery and mortality rates using the SIRD model applied to the first 30, 60, 150 and 300 days of the pandemic. Moreover, a mixture of normal distributions was fitted to the number of confirmed cases and deaths during the first 300 days. The estimates of peaks’ means and variances were used to identify countries with outlying parameters. For the period of 300 days Belgium, Cyprus, France, the Netherlands, Serbia and the UK were classified as outliers by all three outlier detection methods. Yemen was classified as an outlier for each of the four considered timeframes, due to high mortality rates. During the first 300 days of the pandemic the majority of countries underwent three peaks in the number of confirmed cases, except Australia and Kazakhstan with two peaks.


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