Social network-based cohorting to reduce the spread of SARS-CoV-2 in secondary schools: A simulation study in classrooms of four European countries.

BACKGROUND: Operating schools safely under pandemic conditions is a widespread policy goal. We analyse the effectiveness of classroom cohorting, i.e., the decomposition of classrooms into smaller isolated units, in inhibiting the spread of SARS-CoV-2 in European secondary schools and compare different cohorting strategies. METHODS: Using real-world network data on 12,291 adolescents collected in classrooms in England, Germany, the Netherlands, and Sweden in 2010/2011, we apply agent-based simulations to compare the effect of forming cohorts randomly to network-based cohorting. Network-based cohorting attempts to allocate out-of-school contacts to the same cohort to prevent cross-cohort infection more effectively. We consider explicitly minimizing out-of-school cross-cohort contacts, approximating this information-heavy optimization strategy by chained nominations of contacts, and dividing classrooms by gender. We also compare the effect of instructing cohorts in-person every second week to daily but separate in-person instruction of both cohorts. FINDINGS: We find that cohorting reduces the spread of SARS-CoV-2 in classrooms. Relative to random cohorting, network-based strategies further reduce infections and quarantines when transmission dynamics are strong. In particular, network-based cohorting inhibits superspreading in classrooms. Cohorting that explicitly minimizes cross-cohort contacts is most effective, but approximation based on chained nominations and classroom division by gender also outperform random cohorting. Every-second-week instruction in-person contains outbreaks more effectively than daily in-person instruction of both cohorts. INTERPRETATION: Cohorting of school classes can curb SARS-CoV-2 outbreaks in the school context. Factoring in out-of-school contacts can achieve a more effective separation of cohorts. Network-based cohorting reduces the risk of outbreaks in schools and can prevent superspreading events. FUNDING: None.

Changes in Turkish- and Resettler-origin Adolescents' Acculturation Profiles of Identification: A Three-year Longitudinal Study from Germany.

Little is known on how ethnic minority adolescents develop acculturation profiles of identification (i.e., how they combine their ethnic and national identification, such as being high on both and thus rather "integrated" or high on ethnic and low on national and thus rather "separated"). In a first step, this 3-year longitudinal study classified Turkish (n = 344) and resettler-origin (n = 121) ethnic minority adolescents living in Germany (Mage = 14.2, SD = 1.54, 51.6% female) according to their levels of ethnic and national identification. Latent profile analyses identified four profiles (separated, integrated, medium-ethnic, low-ethnic) for the former and three profiles (separated, integrated, low-and-medium ethnic) for the latter group. Latent transition analyses revealed considerable instability of profile attributions over time. Integration declined among both groups and results provided no evidence that national group boundaries are more permeable for resettler-origin than for Turkish-origin adolescents. Additional analyses revealed that perceived ethnic discrimination affected the probability to be in a particular profile but did not moderate transition probabilities. Overall, results suggest that during early-to-mid adolescence it is increasingly difficult to uphold a dual identity.

Differential Influence of Same- and Cross-Ethnic Friends on Ethnic-Racial Identity Development in Early Adolescence.

Recent research has shown that peers influence ethnic-racial identity (ERI) development during early adolescence. Arguments based on social identity theory, however, suggest that only same-ethnic but not cross-ethnic friends are important for ERI development. Using longitudinal social network analysis, we examined peer influence of both same- and cross-ethnic friends on ERI attachment and private regard. Data were drawn from six ethnically diverse schools in Western Germany (N = 1,349; Mage  = 13.3). Our results provide empirical evidence for early adolescents' ERI being influenced by same- but less by cross-ethnic friends. Considering peers' ethnicity therefore is crucial for understanding peer influence on ERI development.

Identity threat and identity multiplicity among minority youth: Longitudinal relations of perceived discrimination with ethnic, religious, and national identification in Germany.

The notion that ethnic and religious minority identities are inherently incompatible with the national identities of European immigrant-receiving societies is popular in public discourse. Although findings documenting such negative associations seemingly support this claim, other research shows that the intergroup context matters for the extent to which minorities' ethnic and religious identities are conflicting (i.e., negatively associated) or compatible (i.e., positively associated) with European national identities. However, previous research relied on cross-sectional data and therefore could not capture the dynamic process through which minority youth come to develop compatible or conflicting identification patterns. We extend this work with a longitudinal approach by capturing developmental trajectories of identity multiplicity among ethnic minority early adolescents in Germany over three waves with 9-month intervals. At each measurement point, participants reported their ethnic, religious, and (German) national identification and their experiences with discriminatory treatment. We estimate a cross-lagged panel model to study how identification relates to perceived discrimination and how this affects (changes in) associations between ethnic, religious, and national identification of minority youth. Our results show prevalent positive associations between ethnic, religious, and national identification across minority youth in the sample. Those who report more frequent discrimination, however, lower their (German) national identification over time, which in turn predicts increased minority identification. We conclude that identity threat indeed triggers a development of more conflicting identification patterns.

Young immigrants' host country identification and their friendships with natives: Does relative group size matter?

Recent network research indicates that native youth prefer to befriend immigrants with stronger rather than weaker host country identification. Surprisingly, however, no respective preference of high-identifying immigrants for native friends has been found, and there is little evidence that friends influence immigrants' identification. Seeking to make sense of these unexpected findings, my aims are twofold: First, I reproduce an earlier study using three waves of newly collected network panel data. Second, going beyond a robustness test with better data, I suggest that relative group size within school accounts for earlier findings. I hypothesize that immigrants' host country identification only affects their own friendship choices in schools with high shares of immigrants, because only in those schools they can be picky about befriending natives. Stochastic actor-oriented models support this notion, pointing to an interplay of preferences and opportunities in shaping the relation between host country identification and interethnic friendships.

The Effects of Ethnic Minority Adolescents' Ethnic Self-Identification on Friendship Selection.

This study investigated the effects of ethnic minority adolescents' ethnic self-identification (host country, dual, or heritage country) on friendship choices among ethnic majority and minority peers. Hypotheses were derived from similarity-attraction and social identity theory and tested using longitudinal social network data from 1,004 middle school students (five schools) in Germany. Results showed that ethnic minority adolescents' ethnic self-identification affected friendship selection beyond ethnic homophily. While host country and dual identification was beneficial with respect to friendships with both ethnic majority and minority peers, heritage country identification was detrimental to relations with both of them.

Do national identification and interethnic friendships affect one another? A longitudinal test with adolescents of Turkish origin in Germany.

Previous research has repeatedly found a positive association between immigrants' identification with the receiving society and their share of interethnic friends. That is, immigrants with a low level of national identification have relatively little contact with natives, and vice versa. Earlier cross-sectional studies, however, were not able to draw firm causal conclusions about the direction of causality. Theoretically, four different scenarios exist: The causal arrow might run from identification to friends (A), but also from friends to identification (B) or in both directions (C). Finally, the relationship might be spurious, caused by unobserved joint determinants (D). Using three-wave panel data for adolescents of Turkish origin in Germany, I examine these four scenarios. First-difference models with lagged independent variables that account for both time-invariant unobserved heterogeneity and potential reverse causality provide no evidence of reciprocal effects between national identification and interethnic friendships. This finding contradicts common interpretations of cross-sectional studies.