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On the basis of a semi-realistic SIR microsimulation for Germany and Poland, we show that the R0 parameter interval for which the COVID-19 epidemic stays overcritical but below the capacity limit of the health care system to reach herd immunity is so narrow that a successful implementation of this strategy is likely to fail, which is in contrast to results obtained from classical differential equation models. Our microsimulation is based on official census data and involves household composition and age distribution as the main population structure variables. Outside household contacts are characterised by an out-reproduction number R* which is the only free parameter of the model. For a subcritical domain we compute the time till extinction and prevalence as a function of the initial number of infected individuals and R*. For the Polish city of Wrocław we also discuss the combined impact of testing coverage and contact reduction. For both countries we estimate R* for disease progression until 20th of March 2020.

BackgroundEstimating the actual number of COVID-19 infections is crucial for steering through the COVID-19 pandemic crisis. It is, however, notoriously difficult, as many cases have no or only mild symptoms. Surveillance data for in-household secondary infections offers unbiased samples for COVID-19 prevalence estimation.MethodsWe analyse 16 115 Polish surveillance records to obtain key figures of the COVID-19 pandemic. We propose conservative upper and lower bound estimators for the number of SARS-CoV-2 infections. Further, we estimate age-dependent bounds on the severe case rate, death rate, and the in-household attack rate.ResultsBy maximum likelihood estimates, the total number of COVID-19 cases in Poland as of July 22nd, 2020, is at most around 13 times larger and at least 1.6 times larger than the recorded number. The lower bound on the severeness rate ranges between 0.2% for the 0–39 year-old to 5.7% for older than 80, while the upper bound is between 2.6% and 34.1%. The lower bound on the death rate is between 0.04% for the age group 40–59 to 1.34% for the oldest. Overall, the severeness and death rates grow exponentially with age. The in-household attack ratio is 8.18% for the youngest group and 16.88% for the oldest.ConclusionsThe proposed approach derives highly relevant figures on the COVID-19 pandemic from routine surveillance data, under assumption that household members of detected infected are tested and all severe cases are diagnosed.MOCOSThe MOCOS (MOdellingCOronaSpread) international research group is an interdisciplinary scientific consortium. The following authors are MOCOS members: Barbara Adamik, Marek Bawiec, Viktor Bezborodov, Przemyslaw Biecek, Wolfgang Bock, Marcin Bodych, Jan Pablo Burgard, Tyll Krueger, Agata Migalska, Tomasz Ożański, Barbara Pabjan, Magdalena Rosińska, Piotr Sobczyk and Ewa Szczurek

A simple model describing the dynamics of opinion forming in a two-party society is presented. Using a Monte Carlo simulation, we show what is the role played by the mobility of the electorate and the size of the groups within which opinions are exchanged. Each individual is characterized by its opinion and its susceptibility to the influence of others. We show what is the effect for a party to have a small percentage of supporters who will never change their mind. We determine when a party having at the beginning a smaller number of supporters, could nevertheless win democratic elections. The influence of an external random field (media) is also discussed.

We present a model of a prison with two types of inmates. One (recidivists) is a better organized and has more influence on the formation of opinions, whereas the second one is more susceptible to the influence of internal and external pressure. We study, via computer simulations, the interplay between well-organized minority and the rest and how the final decision, like e.g. starting a riot, depends on such factors as: fraction of recidivists, their initial support of the riot and possibility of contacts among cells. We find that, as expected, the riot is more likely to start if there is more recidivists favoring it at the beginning. The influence of external factors (media) turned out to have a larger impact on the second group of prisoners. Contrary to a common practice, we show that in order to prevent riots it might be better not to block the inter-cell contacts.

The question whether and how to use models in sociology is not a new one but it is still worth to discuss concerning the state of sociological research and current development of research on agent models in sociology and other disciplines. The aim of this paper is to discuss the most effective way of using models in sociology by taking into account essential features of social phenomena and the specific subject of sociological research. In order to do this I present main problems of research subject and methods in sociology. The article is written for a specific purpose, namely, to develop the cooperation between sociology and physics. It is an attempt to present the sociological approach to models for physicists who are not very much familiar with sociological perspective.

Badania przeprowadzono w latach 2012−2014, na próbie mieszkańców Wrocławia oraz na próbie elit, studentów i uczniów szkół średnich, klas maturalnych. Badania prowadzono w zespole osób: P. Czajkowski, S. Kłopot, B. Pabjan, M. Zuber. Badania pamięci zbiorowej są wielodyscyplinarne, w badaniach społecznych pamięci dominuje podejście jakościowe. Inną cechą tego nurtu badań jest przewaga refleksji teoretycznej nad metodologiczną. Artykuł jest próbą wypełnienia tej luki − analizuje możliwości i ograniczenia badań pamięci zbiorowej i specyfikę badania pamięci zbiorowej mieszkańców miasta. Dyskutowane są wybrane przykłady (z badań własnych) ilustrujące takie kwestie, jak: funkcje pomiaru ilościowego w badaniu pamięci zbiorowej, zastosowanie fotografii w analizie odbioru przestrzeni miejskiej, badanie zbiorowej recepcji przeszłości miasta i wykorzystanie eksperymentu naturalnego do badań. The research on collective memory has few important charactersitics: it is regarded as an mulitdisciplinary field, it is dominated by the qualitative approach, there is relatively well developed theoretical analysis but less methodological reflections. The paper attempts to fill this gap by analysing the selected issues of quantitative research on collective memory and the specificity of researching the collective memory of local city community. The paper discusses the selected examples (from author’s research) illustrating such issues as the effects of quantitative measurement to understand how the collective memory is formed, the use of photographs to examine the reception of the urban space, the study of reception of the city history and the application of the natural experiment to survey techniques. Publikacja finansowana ze środków Wydziału Nauk Społecznych Uniwersytetu Wrocławskiego. W artykule przedstawiono wyniki badań empirycznych przeprowadzonych w ramach międzynarodowego projektu badawczego “The Memory of vanished populations” sfinansowanego przez The Swedish Bank Tercennary Foundation i prowadzonego we współpracy z Uniwersytetem w Lund.

The assumption that society is a complex system is a common and trivial in sociology. Most of the great sociological theories treat society as a complex system explicitly or implicitly. Because social system is always multidimensional it is easier to build such a theory than to apply it to practice. Therefore, it is still not fully explored issue, especially when theory meets empirical data. The aim of this article is to examine the complexity of a social system on the example of prison. The main issues discussed here are: the interplay of elements of the system and its consequences, dynamics of social process, influence of social change and interdependence of microsystem and macrosystem. The article presents the sociological perspective on social system.