144 Probable Delirium is A Presenting Symptom of COVID-19 in Frail, Older Adults: A Study of Hospitalised and Community-Based Cohorts

Introduction

COVID-19 exhibits a more severe disease course in older adults with frailty. Awareness of atypical presentations is critical to facilitate early disease identification. This study aimed to assess how frailty affects presenting symptoms of COVID-19 in older adults.

Methods

Observational study of two distinct cohorts: (i) Hospitalised patients aged 65 and over; unscheduled admission to a large London teaching hospital between March 1st, 2020-May 5th, 2020; COVID-19 confirmed by RT-PCR of nasopharyngeal swab (n = 322); (ii) Community-based adults aged 65 and over enrolled in the COVID Symptom Study mobile application between March 24th (application launch)-May 8th, 2020; self-report or report-by-proxy data; reported test-positive for COVID-19 (n = 535). Multivariable logistic regression analysis performed on age-matched samples of both cohorts to determine associations between frailty and symptoms of COVID-19 including delirium, fever and cough.

Results

Hospital cohort: there was a significantly higher prevalence of delirium amongst the frail sample, with no difference in fever or cough. Of those presenting with delirium, 10/53 (18.9%) presented with delirium as the only documented symptom. Community-based cohort: there was a significantly higher prevalence of probable delirium in the frail sample, and also of fatigue and shortness of breath. Of those reporting probable delirium, 28/84 (33%) did not report fever or cough.

Conclusions

This study demonstrates a higher prevalence of delirium as a presenting symptom of COVID-19 infection in older adults with frailty compared to their age-matched non-frail counterparts. Clinicians should suspect COVID-19 in frail older adults presenting with delirium. Early detection facilitates infection control measures to mitigate against catastrophic spread and preventable hospitalisations and deaths amongst this population. Our findings emphasise the need for systematic frailty assessment for all acutely ill older patients in both hospital and community settings, as well as systematic evaluation of any change in mental status.

Antibody repertoire development in cartilaginous fish

There are 3 H chain and 3 L chain isotypes in the cartilaginous fish, all encoded by genes in the so-called cluster (VDDJ, VJ) organization. The H chain isotypes IgM and IgNAR, are readily detected at the protein level in most species. The third is readily identified at the protein level in skates (IgR) but only via immunoprecipitation or at the transcript level in sharks (IgW). High levels of diversity in CDR3 and up to 200 germline genes have been detected for IgM depending upon the species examined. IgNAR displays very high levels of CDR3 diversity but almost none in the germline. At least IgNAR and L chain genes have been shown to hypermutate to very high levels, apparently in response to antigen. The mutation footprints are similar to those in mammals except that the shark genes uniquely mutate nucleotide residues in tandem. A conspicuous feature of cartilaginous fish Ig genes is the presence of germline-joined genes, which are a result of RAG activity in germ cells. Such genes are expressed early in ontogeny and then extinguished or expressed at lower levels. 19S IgM and IgW expression precede that of 7S IgM and IgNAR during ontogeny. The 'switch' from 19S to 7S IgM, the regulation of expression of the Ig clusters, and the microenvironments for mutation/selection of cartilaginous fish B cells are all areas of ongoing research.

Stabilization of antibody fragments in adverse environments

Antibody fragments have the potential to be used as sensitive and specific binding agents in a broad range of industrial applications. Genetic manipulation has been used to design a series of antibody fragment configurations with a flexible linker and/or a disulphide bond between the heavy chain and light chain of an antibody fragment against the herbicide atrazine. The thermostability and stability to a range of denaturants, polar and non-polar solvents, surfactants and proteases have been compared. It has been found that a novel antibody fragment construct (STAB: stabilized antibody) containing both a flexible linker and a disulphide bond can be effectively produced and shows greatly improved stability in these diverse environments. These STABs should be useful in environmental diagnostics and remediation, and may provide a generic approach for stabilizing antibody fragments in formulations containing detergents and penetrants for topical application in the pharmaceutical and cosmetic industries.