Delta and Omicron: protective measures and SARS-CoV-2 infections in day care centres in Germany in the 4th and 5th wave of the pandemic 2021/2022.

BACKGROUND: During the five waves of the SARS-CoV-2 pandemic so far, German early childhood education and care (ECEC) centres implemented various protective measures, such as wearing a face mask, fixed children-staff groups or regular ventilation. In addition, parents and ECEC staff were increasingly vaccinated throughout 2021. During the 4th wave, variant of concern (VOC) Delta-driven transmission indicators reached record values at the end of 2021. Those values were even exceeded in the 5th wave at the beginning of 2022 when Omicron dominated. We examine which factors facilitated or prevented infection with SARS-CoV-2 in ECEC centres, and if these differed between different phases within wave 4 (Delta) and 5 (Omicron). METHODS: Since August 2020, a weekly online survey among approximately 8000 ECEC managers has been conducted, monitoring both incident SARS-CoV-2 infections and protective measures taken. We included data from calendar week 26/2021 to 05/2022. We estimate the probability of any infections and the number of SARS-CoV-2 infections in children, parents and staff using random-effect-within-between (REWB) panel models for binomial and count data. RESULTS: While children, parents and staff of ECEC centres with a high proportion of children from families with low socioeconomic status (SES) have a higher risk of infections in the beginning of wave 4 (OR up to 1.99 [1.56; 2.56]), this effect diminishes for children and parents with rising incidences. Protective measures, such as wearing face masks, tend to have more extensive effects with rising incidences in wave 5 (IRR up to 0.87 [0.8; 0.93]). Further, the protective effect of vaccination against infection among staff is decreasing from wave 4 to wave 5 (OR 0.3 [0.16; 0.55] to OR 0.95, [0.84; 1.07, n.s.]). The degree of transmission from staff to child and from staff to parent is decreasing from wave 4 to wave 5, while transmission from child to staff seems to increase. CONCLUSION: While Omicron seems to affect children and parents from ECEC centres with families with all SES levels more equally than Delta, the protective effect of vaccination against infection is decreasing and the effect of protective measures like face masks becomes increasingly important. In order to prevent massive closures of ECEC centres due to infection of staff, protective measures should be strictly adhered to, especially to protect staff in centres with a high proportion of children from families with low socioeconomic status.

COVID-19 infections in day care centres in Germany: social and organisational determinants of infections in children and staff in the second and third wave of the pandemic.

BACKGROUND: During the SARS-CoV-2 pandemic, German early childhood education and care (ECEC) centres organised children's attendance in different ways, they reduced opening hours, provided emergency support for a few children, or closed completely. Further, protection and hygiene measures like fixed children-staff groups, ventilation and surface disinfection were introduced in ECEC centres. To inform or modify public health measures in ECEC, we investigate the occurrence of SARS-CoV-2 infections among children and staff in ECEC centres in light of social determinants (i.e. the socioeconomic status of the children) and recommended structural and hygiene measures. We focus on the question if the relevant factors differ between the 2nd (when no variant of concern (VOC) circulated) and the 3rd wave (when VOC B.1.1.7 (Alpha) predominated). METHODS: Based on panel data from a weekly online survey of ECEC centre managers (calendar week 36/2020 to 22/2021, ongoing) including approx. 8500 centres, we estimate the number of SARS-CoV-2 infections in children and staff using random-effect-within-between (REWB) panel models for count data in the 2nd and 3rd wave. RESULTS: ECEC centres with a high proportion of children with low socioeconomic status (SES) have a higher risk of infections in staff and children. Strict contact restrictions between groups like fixed group assignments for children and fixed staff assignments to groups prevent infections. Both effects tend to be stronger in the 3rd wave. CONCLUSION: ECEC centres with a large proportion of children with a low SES background and lack of using fixed child/staff cohorts experience higher COVID-19 rates. Over the long run, centres should be supported in maintaining recommended measures. Preventive measures such as the vaccination of staff should be prioritised in centres with large proportions of low SES children.

[SARS-CoV-2 incidence, transmission, and containment measures in daycare centers during the COVID-19 pandemic-findings from the Corona Daycare Study]. / Infektionsgeschehen und Eindämmungsmaßnahmen in Kitas während der COVID-19-Pandemie ­ Erkenntnisse aus der Corona-KiTa-Studie.

BACKGROUND: Daycare centers are of substantial sociopolitical and pedagogical relevance; at the same time, the close contact of children in daycare groups among each other and with employees favors the transmission of infections. In the COVID-19 pandemic, questions arose about how infection events occur in daycare centers, what role daycare children play in the pandemic, and what protective and hygienic measures are implemented in daycare centers. From 06/2020 to 12/2021, we conducted the "Corona Day Care Study," in which we address pedagogical and infection epidemiological topics in a joint approach. METHODS: In the study, data are collected from different sources. Official reporting data as well as weekly data from daycare centers in the so-called KiTa Register are continuously evaluated. In addition, SARS-CoV­2 outbreaks in daycare centers are investigated on site by repeated sample collection and interviews. RESULTS: SARS-CoV­2 infection incidence in daycare centers or in daycare-aged children was very dynamic from 03/2020 to 05/2021. In the second and third pandemic waves, the number of SARS-CoV­2 outbreaks in daycare centers rose sharply, accompanied by a substantial increase in daycare and group closures. Most recently, the proportion of affected children in outbreaks increased steadily. However, preliminary examinations of SARS-CoV­2 outbreaks (n = 28) revealed that, on average, only a fraction of daycare contact persons (6.8%) were infected by child index cases. Transmission frequencies differed markedly between the individual daycare centers. DISCUSSION: The combination of regularly collected reporting and survey data as well as outbreak investigations allows a multilayered monitoring and understanding of infection events in daycare centers; its findings could be incorporated into recommendations for public health measures.