Background Increased understanding of whether individuals who have recovered from COVID-19 are protected from future SARS-CoV-2 infection is an urgent requirement. We aimed to investigate whether antibodies against SARS-CoV-2 were associated with a decreased risk of symptomatic and asymptomatic reinfection. Methods A large, multicentre, prospective cohort study was done, with participants recruited from publicly funded hospitals in all regions of England. All health-care workers, support staff, and administrative staff working at hospitals who could remain engaged in follow-up for 12 months were eligible to join The SARS-CoV-2 Immunity and Reinfection Evaluation study. Participants were excluded if they had no PCR tests after enrolment, enrolled after Dec 31, 2020, or had insufficient PCR and antibody data for cohort assignment. Participants attended regular SARS-CoV-2 PCR and antibody testing (every 2–4 weeks) and completed questionnaires every 2 weeks on symptoms and exposures. At enrolment, participants were assigned to either the positive cohort (antibody positive, or previous positive PCR or antibody test) or negative cohort (antibody negative, no previous positive PCR or antibody test). The primary outcome was a reinfection in the positive cohort or a primary infection in the negative cohort, determined by PCR tests. Potential reinfections were clinically reviewed and classified according to case definitions (confirmed, probable, or possible) and symptom-status, depending on the hierarchy of evidence. Primary infections in the negative cohort were defined as a first positive PCR test and seroconversions were excluded when not associated with a positive PCR test. A proportional hazards frailty model using a Poisson distribution was used to estimate incidence rate ratios (IRR) to compare infection rates in the two cohorts. Findings From June 18, 2020, to Dec 31, 2020, 30 625 participants were enrolled into the study. 51 participants withdrew from the study, 4913 were excluded, and 25 661 participants (with linked data on antibody and PCR testing) were included in the analysis. Data were extracted from all sources on Feb 5, 2021, and include data up to and including Jan 11, 2021. 155 infections were detected in the baseline positive cohort of 8278 participants, collectively contributing 2 047 113 person-days of follow-up. This compares with 1704 new PCR positive infections in the negative cohort of 17 383 participants, contributing 2 971 436 person-days of follow-up. The incidence density was 7·6 reinfections per 100 000 person-days in the positive cohort, compared with 57·3 primary infections per 100 000 person-days in the negative cohort, between June, 2020, and January, 2021. The adjusted IRR was 0·159 for all reinfections (95% CI 0·13–0·19) compared with PCR-confirmed primary infections. The median interval between primary infection and reinfection was more than 200 days. Interpretation A previous histo...

Over the past two decades, Acinetobacter baumannii has emerged as a leading cause of nosocomial infections worldwide. Of particular concern are pan-resistant strains, leading the World Health Organization (WHO) to designate carbapenem-resistant A. baumannii as a Priority 1 (Critical) pathogen for research and development of new antibiotics. A key component in supporting this effort is accessibility to diverse and clinically relevant strains for testing. Herein we describe a panel of 100 diverse A. baumannii strains for use in this endeavor. Whole genome sequencing was performed on 3,505 A. baumannii housed at the Multidrug resistant organism Repository and Surveillance Network. Isolates were cultured from clinical samples at healthcare facilities around the world between 2001 and 2017. Core-genome multi-locus sequence typing and high-resolution SNP-based phylogenetic analyses were used to select a final panel of 100 strains that captured the genetic diversity of the collection. Comprehensive antibiotic susceptibility testing was also performed on all 100 isolates using 14 clinically-relevant antibiotics. The final 100-strain diversity panel contained representative strains from 70 different traditional Pasteur scheme multi-locus sequence types, including major epidemic clones. This diversity was also reflected in antibiotic susceptibility and antimicrobial resistance (AMR) gene content, with phenotypes ranging from pan-sensitive to pan-resistant, and over 100 distinct AMR gene alleles identified from 32 gene families. This panel provides the most diverse and comprehensive set of A. baumannii strains for use in developing solutions to antibiotic resistance. The panel, and all available meta-data including genome sequences, will be available to industry, academic institutions, federal and other laboratories free-of-charge.

Objective: To determine antibody levels and estimate incidence of infection with pandemic (H1N1) 2009 influenza in children and pregnant women during the 2009 winter in Western Australia. Design, setting and participants: Two cross‐sectional serosurveys using stored specimens collected for unrelated pathology testing, from before and after (3 August to 30 November 2009) circulation of the pandemic virus, and before commencement of the pandemic vaccination program. Specimens were from three groups: children aged 1–4 years, older children and teenagers aged 5–19 years, and pregnant women aged 21–45 years. The groups were geographically representative of the WA population. Main outcome measures: Reactivity against pandemic (H1N1) 2009 and seasonal A(H1N1) influenza viruses measured using haemagglutination inhibition (HI) assays. Results: Antibody titres were determined for 648 individuals in the prepandemic period and 736 in the postpandemic period. In the prepandemic period, HI titres ≥ 40 against the pandemic virus were found in 0 (95% CI, 0.0%–1.6%) children aged 1–4 years, 8.3% (95% CI, 5.3%–12.7%) of older children and teenagers, and 4.5% (95% CI, 2.4%–8.3%) of pregnant women. In postpandemic specimens collected from 1 September 2009 (when influenza activity had declined to near‐baseline levels), estimated infection rates (subtracting prepandemic levels) were 25.4% (95% CI for difference, 18.6%–33.4%) in 1–4‐year‐old children, 39.4% (95% CI, 29.8%–48.5%) in older children and teenagers, and 10.2% (95% CI, 4.1%–17.1%) in pregnant women. Conclusions: A quarter of preschool children and about 40% of school‐aged children and older teenagers had serological evidence of pandemic influenza infection during winter 2009, indicating high levels of mild or asymptomatic infection. The infection rate in pregnant women was much lower. The high infection rates in children help explain the reduced impact of the pandemic virus during the 2010 winter. Augmented by vaccination, there should be sufficiently high levels of immunity in the Australian population to significantly reduce the impact of the virus in future influenza seasons.

Whole-genome sequencing (WGS) of historical clinical isolates identified a chromosomal copy of within a Tn-like transposon in MRSN 12280. The isolate was nonsusceptible to colistin by broth microdilution, and genome analysis revealed no mutations known to confer colistin resistance. To the best of our knowledge, this is the first report of in colistin-nonsusceptible .

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