Compliance with infection prevention and control (IPC) measures is critical to preventing COVID-19 transmission in healthcare settings.

To identify and explain factors influencing compliance with COVID-19-specific IPC measures among healthcare workers (HCWs) in long-term care facilities (LTCF) in Finland.

The study included a web-based survey and qualitative study based on the Theoretical Domains Framework (TDF). The link to the anonymous survey was distributed via email to LTCFs through regional IPC experts in December 2020. Outcome was modelled using ordinary logistic regression and penalised ridge logistic regression using regrouped explanatory variables and an original, more correlated set of explanatory variables, respectively. In-depth interviews were conducted among survey participants who volunteered during January–March 2021. Data were analysed thematically using qualitative data analysis software (NVIVO12).

A total of 422 HCWs from 17/20 regions responded to the survey. Three TDF domains were identified that negatively influenced IPC compliance: environmental context and resources, reinforcement and beliefs about capabilities. Twenty HCWs participated in interviews, which resulted in identification of several themes: changes in professional duties and lack of staff planning for emergencies (domain: environmental context and resources); management culture and physical absence of management (domain: reinforcement), knowledge of applying IPC measures, nature of tasks and infrastructure that supports implementation (domain: beliefs about capabilities), that explained how the domains negatively influenced their IPC behaviour.

This study provides insights into behavioural domains that can be used in developing evidence-based behaviour change interventions to support HCW compliance with pandemic-specific IPC measures in LTCFs.

Data regarding the long-term protection afforded by vaccination for the SARS-CoV-2 infection are essential for allocation of scarce vaccination resources worldwide.

We conducted a retrospective cohort study aimed at studying the kinetics of IgG antibodies against SARS-CoV-2 in COVID-19-naïve patients fully vaccinated with two doses of Comirnaty mRNA COVID-19 vaccine. Geometric mean concentrations (GMCs) of antibody levels were reported. Linear models were used to assess antibody levels after full vaccination and their decline over time.

The study included 4,740 patients and 5,719 serological tests. Unadjusted GMCs peaked 28–41 days after the first dose at 10,174 AU/mL (95% CI: 9,211–11,237) and gradually decreased but remained well above the positivity cut-off. After adjusting for baseline characteristics and repeated measurements, the antibodies half-life time was 34.1 days (95% CI: 33.1–35.2), and females aged 16–39 years with no comorbidities had antibody levels of 20,613 AU/mL (95% CI: 18,526–22,934) on day 28 post-first-dose. Antibody levels were lower among males (0.736 of the level measured in females; 95% CI: 0.672–0.806), people aged 40–59 (0.729; 95% CI: 0.649–0.818) and ≥ 60 years (0.452; 95% CI: 0.398–0.513), and patients having haematological (0.241; 95% CI: 0.190–0.306) or solid malignancies (0.757; 95% CI: 0.650–0.881), chronic kidney disease with glomerular filtration rate (GFR) ≥ 30 (0.434; 95% CI: 0.354–0.532) or with GFR < 30 mL/min (0.176; 95% CI: 0.109–0.287), and immunosuppression (0.273; 95% CI: 0.235–0.317). Body mass index, cardiovascular disease, congestive heart failure, chronic obstructive pulmonary disease, diabetes and inflammatory bowel diseases were not associated with antibody levels.

Vaccination with two doses resulted in persistently high levels of antibodies (≥ cut-off of 50 AU/mL) up to 137 days post-first-dose. Risk factors for lower antibody levels were identified.