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.

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.

The SARS-CoV-2 Delta variant (B.1.617.2) is associated with increased infectivity. Data on breakthrough SARS-CoV-2 Delta variant infections in vaccinated individuals and transmission risk are limited. The aim of this study was to provide estimates of transmission risk in Delta variant breakthrough infections. A matched case-control study was performed.. To analyse onward transmission of fully vaccinated individuals infected with B.1.617.2, we compared 85 patients (vaccination group [VG]) with an age- and sex-matched unvaccinated control group (CG; n = 85). Transmission of B.1.617.2 was significantly reduced (halved) in the VG. The number of infected contacts to total number of contacts per infected person was 0.26 ± 0.40 in the VG vs 0.56 ± 0.45 in the CG (P = .001). Similarly, fully vaccinated contacts were less likely to be infected by fully vaccinated infected persons (IPs) than by unvaccinated IPs (20.0% vs 37.5%), although this association was not significant. Fully vaccinated contacts had 50% less transmissions than unvaccinated individuals. These findings must be verified in larger sample populations, and it is especially important to investigate the role of vaccination status of close contacts.

Die SARS-CoV-2-Pandemie hat das menschliche Leben erheblich eingeschränkt. Zur Bekämpfung der Ausbreitung wurden infizierte Personen (IP) und ihre engen Kontaktpersonen (KP) in Deutschland seit Februar/März 2020 isoliert bzw. unter Quarantäne gestellt. Im Rahmen des CoCo-Fakt-Surveys (Cologne-Corona-Beratung und Unterstützung Für Index- und KontAKt-Personen während der Quarantäne-ZeiT) wurde neben der Adhärenz bzgl. der Quarantäneregeln der Gesundheitszustand, die Symptomatik, psychische Belastung, Bewältigungsstrategien (Coping-Score) sowie der individuelle Lebensstil (u.a. körperliche Aktivität, Ernährung/Gewichtsentwicklung) erfasst. Methodik Der online-basierte CoCo-Fakt-Survey wurde an alle durch das Kölner Gesundheitsamt registrierten IPs und KPs versendet (n=33699), die bis zum 9.12.20 in behördlich angeordnete Quarantäne gesetzt wurden. Ausgeschlossen wurden Personen unter 16 Jahre und ohne Mailadresse, hospitalisierte bzw. verstorbene Betroffene sowie Pflegeheim-Bewohner. Schwangere erhielten einen eigenen Fragebogen. Ergebnisse Von 13.057 Personen wurden nach der Datenbereinigung 4.065 IPs (38,8%) bzw. 6.425 KPs (61,2%) in diese Auswertung integriert. Die Quarantänedauer lag bei 11.8+/-4.6 Tagen. 60% der Personen waren weiblich, der Altersdurchschnitt betrug 40.8+/-14.2 Jahre. 80.0% hatten einen hohen, 19.1% einen mittleren und 0.9% einen geringen Bildungsgrad; 5.4% hatten Migrationshintergrund. IPs gaben eine signifikant höhere psychische Belastung an als KPs, der Coping-Score unterschied sich nicht zwischen beiden Gruppen. Die meisten Teilnehmenden nutzten aktive Bewältigungsstrategien wie Kontakte mit dem sozialen Umfeld, eine positive Einstellung und Hobbys. Die körperliche Aktivität sank während der Quarantäne um 48,2% bei IPs und um 27,1% bei KPs. Personen, die während der Quarantäne aktiv waren, fühlten sich in dieser Zeit fitter, weniger müde und weniger erschöpft. Während der Quarantänezeit nahmen IPs 1,2+/-4.4 kg ab, KPs 1,6+/-4.1 kg zu. Als Gründe für eine Gewichtsänderung gaben die IPs v.a. Geschmacksverlust und Krankheitsgefühl an, Kontaktpersonen aßen eher aus Langeweile. Fazit Die gesetzlich verordnete Quarantäne wirkt sich bei IPs sowie KPs in unterschiedlicher Weise auf die psychische Situation, aber auch den Lebensstil aus. Um neben Long-COVID auch weitere mögliche Langzeitfolgen zu vermeiden, sollte eine enge Betreuung durch den öffentlichen Gesundheitsdienst bzw. anschließend in der Hausarztpraxis erfolgen. Literatur Joisten C, Kossow A, Book J, et al. How to manage quarantine-adherence, psychosocial consequences, coping strategies and lifestyle of patients with COVID-19 and their confirmed contacts: study protocol of the CoCo-Fakt surveillance study, Cologne, Germany. BMJ Open 2021; 11: e048001. Interessenskonflikte Es bestehen keine Interessenskonflikte bzgl. der Thematik. C. Joisten erhält Vortragshonorare von Berlin Chemie, MSD Sharpe und Dohme, Novartis, Abbvie, Pfizer, Janssen, Lilly, Menarini, Chieso, Infectopharm, NovoNordisk und Daichi-Sankyo. Publication Date: 26 April 2022 (online) © 2022. Thieme. All rights reserved. Georg Thieme Verlag Rüdigerstraße 14,70469 Stuttgart, Germany

Since its first description in November 2021, the SARS-CoV-2 variant of concern Omicron (B.1.1.529) has emerged as the dominant strain in the COVID-19 pandemic. To date, it remains unclear if boosted vaccination protects against transmission. Using data from the largest German Public Health Department, Cologne, we analyzed breakthrough infections in booster-vaccinated infected persons (IP; booster-vaccinated group (BVG); n = 202) and fully vaccinated, not boosted SARS-COV2-positive patients (>3 month after receiving the second dose; unboosted, fully vaccinated group (FVG); n = 202) to close contacts compared to an age- and sex-matched unvaccinated control group (UCG; n = 202). On average, IPs had 0.42 ± 0.52 infected contacts in relation to the total number of contacts in the BVG vs. 0.57 ± 0.44 in the FVG vs. 0.56 ± 0.43 in the UVG (p = 0.054). In the median test, pairwise comparison revealed a significant difference between the BVG and both other groups; no difference was found between the fully vaccinated and the unvaccinated control group. Now, these findings must be verified in larger samples, considering the role of Omicron subvariants and the vaccination status of the contact person. However, the importance of the booster vaccination in breaking possible chains of infection in the immune escape variant Omicron is obvious.