OBJECTIVES:We aimed to assess the impact of COVID-19 on antibiotic consumption (AMC) and antimicrobial resistance (AMR) in the new epidemiological scenario from a cross-national perspective. METHODS:A quasi-experimental retrospective multicentre ecological study was conducted to explore the impact of COVID-19 on AMC and AMR using routinely generated retrospective time series data. This study included nine Healthcare University Hospitals from Europe and Israel on behalf QUantifying change in Antibiotic Resistance, ANTibiotic use, and INfection control during COVID-19 Epidemics project. Total effects were defined as the difference between the pre-COVID-19 period (ranging from January 2015 or January 2016 to February 2020) and during the COVID-19 pandemic period (March 2020 to July 2021 or December 2021). The outcomes were incidence density (ID) of carbapenem-resistant Acinetobacter baumannii, carbapenem-resistant Klebsiella pneumoniae, extended-spectrum beta-lactamase-producing Escherichia coli, vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus, carbapenem-resistant Pseudomonas aeruginosa and Clostridioides difficile, as monthly isolates per 1000 patient days and the monthly AMC ranked according to the Access, Watch, and Reserve WHO classification system. RESULTS:We assessed 15.9 million total hospital bed days, 315 736 COVID-19 bed days, 52 557 monthly bacterial isolates, and 461 739 monthly antimicrobial defined daily doses. The COVID-19 pandemic had a significant impact on the consumption of overall hospital antibiotics combined in all centres except two. Prescriptions for piperacillin/tazobactam, glycopeptides, and ceftazidime/avibactam increased, whereas third-generation cephalosporins, macrolides, and fluoroquinolones returned to pre-pandemic levels after an initial surge, in all centres. A positive relationship between the pandemic intensity and VRE ID was observed in 6 of 9 (66%) centres followed by methicillin-resistant S. aureus-ID and carbapenem-resistant P. aeruginosa-ID 3 of 4 (44%) for both. A negative relationship was found for extended-spectrum beta-lactamase-producing E. coli ID. DISCUSSION:The COVID-19 pandemic was associated with higher usage of broad-spectrum antibiotics and higher incidence of multidrug-resistant bacteria, with great variability by countries. These results could support international action plans that embed AMR as a priority in the post-COVID-19 era.

Objective To evaluate the dynamics and longevity of the humoral immune response to SARS-CoV-2 infection and assess the performance of professional use of the UK-RTC AbC-19 Rapid Test lateral flow immunoassay (LFIA) for the target condition of SARS-CoV-2 spike protein IgG antibodies. Design Nationwide serological study. Setting Northern Ireland, UK, May 2020–February 2021. Participants Plasma samples were collected from a diverse cohort of individuals from the general public (n=279), Northern Ireland healthcare workers (n=195), pre-pandemic blood donations and research studies (n=223) and through a convalescent plasma programme (n=183). Plasma donors (n=101) were followed with sequential samples over 11 months post-symptom onset. Main outcome measures SARS-CoV-2 antibody levels in plasma samples using Roche Elecsys Anti-SARS-CoV-2 IgG/IgA/IgM, Abbott SARS-CoV-2 IgG and EuroImmun IgG SARS-CoV-2 ELISA immunoassays over time. UK-RTC AbC-19 LFIA sensitivity and specificity, estimated using a three-reference standard system to establish a characterised panel of 330 positive and 488 negative SARS-CoV-2 IgG samples. Results We detected persistence of SARS-CoV-2 IgG antibodies for up to 10 months post-infection, across a minimum of two laboratory immunoassays. On the known positive cohort, the UK-RTC AbC-19 LFIA showed a sensitivity of 97.58% (95.28% to 98.95%) and on known negatives, showed specificity of 99.59% (98.53 % to 99.95%). Conclusions Through comprehensive analysis of a cohort of pre-pandemic and pandemic individuals, we show detectable levels of IgG antibodies, lasting over 46 weeks when assessed by EuroImmun ELISA, providing insight to antibody levels at later time points post-infection. We show good laboratory validation performance metrics for the AbC-19 rapid test for SARS-CoV-2 spike protein IgG antibody detection in a laboratory-based setting.

The SARS-CoV-2 pandemic necessitated rapid and global responses across all areas 38 of healthcare, including an unprecedented interest in serological immunoassays to 39 detect antibodies to the virus. The dynamics of the immune response to SARS-CoV- 40 2 is still not well understood and requires further investigation into the longevity of 41 humoral immune response that is evoked due to SARS-CoV-2 infection. We measured SARS-CoV-2 antibody levels in plasma samples from 880 people in 44 Northern Ireland using Roche Elecsys Anti-SARS-CoV-2 IgG/IgA/IgM, Abbott SARS- 45 CoV-2 IgG and EuroImmun IgG SARS-CoV-2 ELISA immunoassays to analyse immune dynamics over time. We undertook a laboratory evaluation for the UK-RTC 47 AbC-19 rapid lateral flow immunoassay (LFIA), for the target condition of SARS-CoV- 48 2 Spike protein IgG antibodies using a reference standard system to establish a 49 characterised panel of 330 positive and 488 negative SARS-CoV-2 IgG samples. laboratory 61 62

Background The SARS-CoV-2 pandemic necessitated rapid and global responses across all areas of healthcare, including an unprecedented interest in serological immunoassays to detect antibodies to the virus. The dynamics of the immune response to SARS-CoV-2 is still not well understood. Methods We measure SARS-CoV-2 antibody levels in plasma samples from 880 people in Northern Ireland by Roche Elecsys Anti-SARS-CoV-2 IgG/IgA/IgM, Abbott SARS-CoV-2 IgG and EuroImmun IgG SARS-CoV-2 ELISA immunoassays to analyse immune dynamics over time. Using these results, we develop a "pseudo gold standard" reference cohort against which to assess immunoassay performance. We report performance metrics for the UK-RTC AbC-19 rapid lateral flow immunoassay (LFIA) against a characterised panel of 304 positives established using the "pseudo gold standard" system and 350 negative samples. Results We detect persistence of SARS-CoV-2 IgG up to 140 days (20 weeks) post infection, across all three antibody immunoassays, at levels up to 4.4 times the cut-off for a positive result by Roche measurement. Using our "pseudo gold standard" cohort (n=348 positive, n=510 negative) we determine the sensitivity and specificity of the three commercial immunoassays used (EuroImmun; Sens. 98.9% [97.7-99.7%]; Spec. 99.2% [98.4-99.8%]; Roche; Sens. 99.4% [98.6-100%]; Spec. (96.7% [95.1-98.2%]; Abbott; Sens. 86.8% [83.1-90.2%]; Spec. (99.2% [98.4-99.8%]). The UK-RTC AbC-19 lateral flow immunoassay using shows a sensitivity of 97.70% (95.72%-99.34%) and specificity of 100% (100.00-100.00%). Conclusions Through comprehensive analysis of a large cohort of pre-pandemic and pandemic individuals, we show detectable levels of IgG antibodies, lasting up to 140 days, providing insight to immunity levels at later time points. We propose an alternative to RT-PCR positive status as a standard for assessing SARS-CoV-2 antibody assays and show strong performance metrics for the AbC-19 rapid test.