Background and Methods: Vaccination is currently considered the most successful strategy for combating the SARS-CoV-2 virus. According to short-term clinical trials, protection against infection is estimated to reach up to 95% after complete vaccination (≥14 days after receipt of all recommended COVID-19 vaccine doses). Nevertheless, infections despite vaccination, so-called breakthrough infections, are documented. Even though they are more likely to have a milder or even asymptomatic course, the assessment of further transmission is highly relevant for successful containment. Therefore, we calculated the real-world transmission risk from fully vaccinated patients (vaccination group, VG) to their close contacts (CP) compared with the risk from unvaccinated reference persons matched according to age, sex, and virus type (control group = CG) utilizing data from Cologne’s health department. Results: A total of 357 breakthrough infections occurred among Cologne residents between 27 December 2020 (the date of the first vaccination in Cologne) and 6 August 2021. Of the 979 CPs in VG, 99 (10.1%) became infected. In CG, 303 of 802 CPs (37.8%) became infected. Factors promoting transmission included non-vaccinated status (β = 0.237; p < 0.001), male sex (β = 0.079; p = 0.049), the presence of symptoms (β = −0.125; p = 0.005), and lower cycle threshold value (β = −0.125; p = 0.032). This model explained 14.0% of the variance (corr. R2). Conclusion: The number of transmissions from unvaccinated controls was three times higher than from fully vaccinated patients. These real-world data underscore the importance of vaccination in enabling the relaxation of stringent and restrictive general pandemic control measures.

Systematic SARS-CoV-2 testing is a valuable tool for infection control and surveillance. However, broad application of high sensitive RT-qPCR testing in children is often hampered due to unpleasant sample collection, limited RT-qPCR capacities and high costs. Here, we developed a high-throughput approach (‘Lolli-Method’) for SARS-CoV-2 detection in children, combining non-invasive sample collection with an RT-qPCR-pool testing strategy. SARS-CoV-2 infections were diagnosed with sensitivities of 100% and 93.9% when viral loads were >106 copies/ml and >103 copies/ml in corresponding Naso-/Oropharyngeal-swabs, respectively. For effective application of the Lolli-Method in schools and daycare facilities, SEIR-modeling indicated a preferred frequency of two tests per week. The developed test strategy was implemented in 3,700 schools and 698 daycare facilities in Germany, screening over 800,000 individuals twice per week. In a period of 3 months, 6,364 pool-RT-qPCRs tested positive (0.64%), ranging from 0.05% to 2.61% per week. Notably, infections correlated with local SARS-CoV-2 incidences and with a school social deprivation index. Moreover, in comparison with the alpha variant, statistical modeling revealed a 36.8% increase for multiple (≥2 children) infections per class following infections with the delta variant. We conclude that the Lolli-Method is a powerful tool for SARS-CoV-2 surveillance and can support infection control in schools and daycare facilities.

IntroductionThe current coronavirus (SARS-CoV-2) pandemic has placed unprecedented restrictions on people’s lives and routines. To counteract the exponential spread of this virus, a lockdown was implemented in Germany in March 2020. Infected persons and their contacts were also quarantined. Compliance with quarantine measures is essential for containing the spread of the virus and avoiding incalculable consequences in terms of morbidity and mortality. On the other hand, prolonged homestays, particularly quarantining, may lead to fear, panic, anxiety and depression. Hence, determining the psychological response in people during quarantine and their coping strategies is relevant for the counselling and support of affected persons by healthcare workers.Methods and analysisThe CoCo-Fakt-Survey (Cologne-Corona-Beratung und Unterstützung Für Index- und KontAKt-Personen während der Quarantäne-ZeiT; Cologne-Corona counselling and support for index and contacts during the quarantine period—author’s translation) will examine a cohort of persons in Cologne quarantined since the beginning of the SARS-CoV-2 outbreak during March 2020. The questionnaire will include demographic data, transmission route, health status, knowledge of and adherence to quarantine measurements, psychological impact on individuals and their family members including children, mental health status, and lifestyle (physical activity/sedentary behaviour, relaxation techniques, nutrition, smoking). All Cologne residents who needed to be quarantined due to a coronavirus infection and the individuals with whom they had contact will be surveyed.Ethics and disseminationNo risks have been identified and no complications are expected. Ethics approval was obtained from the Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen Human Ethics Research Committee (351/20), and the research will be conducted in accordance with the approved protocol. The results will be disseminated through peer-reviewed journals and social medicine conferences.

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Introduction: Public health measures enacted to reduce COVID-19 transmission have affected individuals’ lifestyles, mental health and psychological well-being. To date, little is known how stay-at-home orders have influenced the eating behaviors, weight development, and alcohol consumption of quarantined persons. The CoCo-Fakt cohort study analyzed these parameters and their association with psychological distress and coping strategies. Methods: An online survey was conducted of all persons who tested positive for SARS-CoV-2 (infected persons = IP) between December 12, 2020, and January 6, 2021, as well as their close contacts (contact persons = CP) registered by the public health department of Cologne. 8,075 of 33,699 individuals were included in the analysis. In addition to demographic data, psychological distress, and coping strategies, information on changes in body weight, eating and drinking behaviors was collected. Results: IP lost 1.2 ± 4.4 kg during the quarantine period, and CP gained 1.6 ± 4.1 kg. The reasons given by IP for weight change were mainly loss of taste and feeling sick, whereas CP were more likely than IP to eat out of boredom. Higher psychological burden and lower coping strategies were associated with both weight gain and loss. Of the 30.8% of participants who changed their alcohol consumption during the quarantine period, CP in particular drank more alcohol (IP 15.2%; CP 47.7%). Significantly less alcohol was consumed by individuals with higher coping scores. Conclusion: In this short but psychologically stressful period of stay-at-home orders, changes in eating and drinking behavior as well as weight development are evident; mainly in high-risk contacts. To avoid possible long-term sequelae, health authorities should take these findings into account during the quarantine period; in particular, general practitioners should consider these findings during follow-up.