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Previous studies have associated COVID-19 symptoms severity with levels of physical activity. We therefore investigated longitudinal trajectories of COVID-19 symptoms in a cohort of healthcare workers (HCWs) with non-hospitalised COVID-19 and their real-world physical activity. 121 HCWs with a history of COVID-19 infection who had symptoms monitored through at least two research clinic visits, and via smartphone were examined. HCWs with a compatible smartphone were provided with an Apple Watch Series 4 and were asked to install the MyHeart Counts Study App to collect COVID-19 symptom data and multiple physical activity parameters. Unsupervised classification analysis of symptoms identified two trajectory patterns of long and short symptom duration. The prevalence for longitudinal persistence of any COVID-19 symptom was 36% with fatigue and loss of smell being the two most prevalent individual symptom trajectories (24.8% and 21.5%, respectively). 8 physical activity features obtained via the MyHeart Counts App identified two groups of trajectories for high and low activity. Of these 8 parameters only 'distance moved walking or running' was associated with COVID-19 symptom trajectories. We report a high prevalence of long-term symptoms of COVID-19 in a non-hospitalised cohort of HCWs, a method to identify physical activity trends, and investigate their association. These data highlight the importance of tracking symptoms from onset to recovery even in non-hospitalised COVID-19 individuals. The increasing ease in collecting real-world physical activity data non-invasively from wearable devices provides opportunity to investigate the association of physical activity to symptoms of COVID-19 and other cardio-respiratory diseases., (© 2023. The Author(s).)

The prevalence and strength of serological responses mounted toward SARS-CoV-2 proteins other than nucleocapsid (N) and spike (S), which may be of use as additional serological markers, remains underexplored. Using high-content microscopy to assess antibody responses against full-length StrepTagged SARS-CoV-2 proteins, we found that 85% (166/196) of unvaccinated individuals with RT-PCR confirmed SARS-CoV-2 infections and 74% (31/42) of individuals infected after being vaccinated developed detectable IgG against the structural protein M, which is higher than previous estimates. Compared with N antibodies, M IgG displayed a shallower time-dependent decay and greater specificity. Sensitivity for SARS-CoV-2 seroprevalence was enhanced when N and M IgG detection was combined. These findings indicate that screening for M seroconversion may be a good approach for detecting additional vaccine breakthrough infections and highlight the potential to use HCM as a rapidly deployable method to identify the most immunogenic targets of newly emergent pathogens., Competing Interests: The authors declare no competing interests., (© 2023 The Author(s).)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune responses and infection outcomes were evaluated in 2,686 patients with varying immune-suppressive disease states after administration of two Coronavirus Disease 2019 (COVID-19) vaccines. Overall, 255 of 2,204 (12%) patients failed to develop anti-spike antibodies, with an additional 600 of 2,204 (27%) patients generating low levels (<380 AU ml -1 ). Vaccine failure rates were highest in ANCA-associated vasculitis on rituximab (21/29, 72%), hemodialysis on immunosuppressive therapy (6/30, 20%) and solid organ transplant recipients (20/81, 25% and 141/458, 31%). SARS-CoV-2-specific T cell responses were detected in 513 of 580 (88%) patients, with lower T cell magnitude or proportion in hemodialysis, allogeneic hematopoietic stem cell transplantation and liver transplant recipients (versus healthy controls). Humoral responses against Omicron (BA.1) were reduced, although cross-reactive T cell responses were sustained in all participants for whom these data were available. BNT162b2 was associated with higher antibody but lower cellular responses compared to ChAdOx1 nCoV-19 vaccination. We report 474 SARS-CoV-2 infection episodes, including 48 individuals with hospitalization or death from COVID-19. Decreased magnitude of both the serological and the T cell response was associated with severe COVID-19. Overall, we identified clinical phenotypes that may benefit from targeted COVID-19 therapeutic strategies., (© 2023. The Author(s).)

Background: Both infection and vaccination, alone or in combination, generate antibody and T cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the maintenance of such responses-and hence protection from disease-requires careful characterization. In a large prospective study of UK healthcare workers (HCWs) (Protective Immunity from T Cells in Healthcare Workers [PITCH], within the larger SARS-CoV-2 Immunity and Reinfection Evaluation [SIREN] study), we previously observed that prior infection strongly affected subsequent cellular and humoral immunity induced after long and short dosing intervals of BNT162b2 (Pfizer/BioNTech) vaccination., Methods: Here, we report longer follow-up of 684 HCWs in this cohort over 6-9 months following two doses of BNT162b2 or AZD1222 (Oxford/AstraZeneca) vaccination and up to 6 months following a subsequent mRNA booster vaccination., Findings: We make three observations: first, the dynamics of humoral and cellular responses differ; binding and neutralizing antibodies declined, whereas T and memory B cell responses were maintained after the second vaccine dose. Second, vaccine boosting restored immunoglobulin (Ig) G levels; broadened neutralizing activity against variants of concern, including Omicron BA.1, BA.2, and BA.5; and boosted T cell responses above the 6-month level after dose 2. Third, prior infection maintained its impact driving larger and broader T cell responses compared with never-infected people, a feature maintained until 6 months after the third dose., Conclusions: Broadly cross-reactive T cell responses are well maintained over time-especially in those with combined vaccine and infection-induced immunity ("hybrid" immunity)-and may contribute to continued protection against severe disease., Funding: Department for Health and Social Care, Medical Research Council., Competing Interests: Declaration of interests S.J.D. is a Scientific Advisor to the Scottish Parliament on COVID-19, for which she receives a fee. A.J.P. is Chair of UK Department of Health and Social Care’s (DHSC) Joint Committee on Vaccination and Immunisation (JCVI) but does not participate in policy decisions on COVID-19 vaccines. He was previously a member of the WHO’s SAGE. The views expressed in this article do not necessarily represent the views of DHSC, JCVI, or WHO. A.J.P. is chief investigator on clinical trials of Oxford University’s COVID-19 vaccine funded by NIHR. Oxford University has entered a joint COVID-19 vaccine development partnership with AstraZeneca. G.S. sits on the GSK Vaccines Scientific Advisory Board and is a founder member of RQ Biotechnology., (Copyright © 2023. Published by Elsevier Inc.)

Two doses of BNT162b2 mRNA vaccine induces a strong systemic SARS-CoV-2 specific humoral response. However, SARS-CoV-2 airborne transmission makes mucosal immune response a crucial first line of defense. Therefore, we characterized SARS-CoV-2-specific IgG responses induced by BNT162b2 vaccine, as well as IgG responses to other pathogenic and seasonal human coronaviruses in oral fluid and plasma from 200 UK healthcare workers who were naïve (N=62) or previously infected with SARS-CoV-2 (N=138) using a pan-coronavirus multiplex binding immunoassay (Meso Scale Discovery ® ). Additionally, we investigated the impact of historical SARS-CoV-2 infection on vaccine-induced IgG, IgA and neutralizing responses in selected oral fluid samples before vaccination, after a first and second dose of BNT162b2, as well as following a third dose of mRNA vaccine or breakthrough infections using the same immunoassay and an ACE2 inhibition assay. Prior to vaccination, we found that spike-specific IgG levels in oral fluid positively correlated with IgG levels in plasma from previously-infected individuals (Spearman r=0.6858, p<0.0001) demonstrating that oral fluid could be used as a proxy for the presence of plasma SARS-CoV-2 IgG. However, the sensitivity was lower in oral fluid (0.85, 95% CI 0.77-0.91) than in plasma (0.94, 95% CI 0.88-0.97). Similar kinetics of mucosal and systemic spike-specific IgG levels were observed following vaccination in naïve and previously-infected individuals, respectively. In addition, a significant enhancement of OC43 and HKU1 spike-specific IgG levels was observed in previously-infected individuals following one vaccine dose in oral fluid (OC43 S: p<0.0001; HKU1 S: p=0.0423) suggesting cross-reactive IgG responses to seasonal beta coronaviruses. Mucosal spike-specific IgA responses were induced by mRNA vaccination particularly in previously-infected individuals (71%) but less frequently in naïve participants (23%). Neutralizing responses to SARS-CoV-2 ancestral and variants of concerns were detected following vaccination in naïve and previously-infected participants, with likely contribution from both IgG and IgA in previously-infected individuals (correlations between neutralizing responses and IgG: Spearman r=0.5642, p<0.0001; IgA: Spearman r=0.4545, p=0.0001). We also observed that breakthrough infections or a third vaccine dose enhanced mucosal antibody levels and neutralizing responses. These data contribute to show that a previous SARS-CoV-2 infection tailors the mucosal antibody profile induced by vaccination., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. However, for prior studies, not related to the research published here, MSD have provided access to early phase assay plates free of charge to MC., (Copyright © 2022 Longet, Hargreaves, Healy, Brown, Hornsby, Meardon, Tipton, Barnes, Dunachie, Duncan, Klenerman, Richter, Turtle, de Silva and Carroll.)

Background: Previous infection with SARS-CoV-2 affects the immune response to the first dose of the SARS-CoV-2 vaccine. We aimed to compare SARS-CoV-2-specific T-cell and antibody responses in health-care workers with and without previous SARS-CoV-2 infection following a single dose of the BNT162b2 (tozinameran; Pfizer-BioNTech) mRNA vaccine., Methods: We sampled health-care workers enrolled in the PITCH study across four hospital sites in the UK (Oxford, Liverpool, Newcastle, and Sheffield). All health-care workers aged 18 years or older consenting to participate in this prospective cohort study were included, with no exclusion criteria applied. Blood samples were collected where possible before vaccination and 28 (±7) days following one or two doses (given 3-4 weeks apart) of the BNT162b2 vaccine. Previous infection was determined by a documented SARS-CoV-2-positive RT-PCR result or the presence of positive anti-SARS-CoV-2 nucleocapsid antibodies. We measured spike-specific IgG antibodies and quantified T-cell responses by interferon-γ enzyme-linked immunospot assay in all participants where samples were available at the time of analysis, comparing SARS-CoV-2-naive individuals to those with previous infection., Findings: Between Dec 9, 2020, and Feb 9, 2021, 119 SARS-CoV-2-naive and 145 previously infected health-care workers received one dose, and 25 SARS-CoV-2-naive health-care workers received two doses, of the BNT162b2 vaccine. In previously infected health-care workers, the median time from previous infection to vaccination was 268 days (IQR 232-285). At 28 days (IQR 27-33) after a single dose, the spike-specific T-cell response measured in fresh peripheral blood mononuclear cells (PBMCs) was higher in previously infected (n=76) than in infection-naive (n=45) health-care workers (median 284 [IQR 150-461] vs 55 [IQR 24-132] spot-forming units [SFUs] per 10 6 PBMCs; p<0·0001). With cryopreserved PBMCs, the T-cell response in previously infected individuals (n=52) after one vaccine dose was equivalent to that of infection-naive individuals (n=19) after receiving two vaccine doses (median 152 [IQR 119-275] vs 162 [104-258] SFUs/10 6 PBMCs; p=1·00). Anti-spike IgG antibody responses following a single dose in 142 previously infected health-care workers (median 270 373 [IQR 203 461-535 188] antibody units [AU] per mL) were higher than in 111 infection-naive health-care workers following one dose (35 001 [17 099-55 341] AU/mL; p<0·0001) and higher than in 25 infection-naive individuals given two doses (180 904 [108 221-242 467] AU/mL; p<0·0001)., Interpretation: A single dose of the BNT162b2 vaccine is likely to provide greater protection against SARS-CoV-2 infection in individuals with previous SARS-CoV-2 infection, than in SARS-CoV-2-naive individuals, including against variants of concern. Future studies should determine the additional benefit of a second dose on the magnitude and durability of immune responses in individuals vaccinated following infection, alongside evaluation of the impact of extending the interval between vaccine doses., Funding: UK Department of Health and Social Care, and UK Coronavirus Immunology Consortium., Competing Interests: CD worked on the Oxford–AstraZeneca COVID-19 vaccine trial (phase 1–3). AO reports personal fees from Take Two Interactive and personal fees from Genome BC, outside the submitted work. PCM reports grants from the Wellcome Trust during the conduct of the study. SLR-J reports grants from the UK Department of Health and Social Care during the conduct of the study and grants from UK Research and Innovation (UKRI), National Institute for Health Research (NIHR), and Global Challenges Research Fund outside the submitted work. SD reports grants from the UK Department of Health and Social Care, UK Coronavirus Immunology Consortium (UKRI), the Huo Family Foundation, and the NIHR during the conduct of the study. CJAD reports grants from the Wellcome Trust during the conduct of the study. LT reports personal fees from Eisai outside the submitted work. All other authors declare no competing interests., (© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.)

Extension of the interval between vaccine doses for the BNT162b2 mRNA vaccine was introduced in the United Kingdom to accelerate population coverage with a single dose. At this time, trial data were lacking, and we addressed this in a study of United Kingdom healthcare workers. The first vaccine dose induced protection from infection from the circulating alpha (B.1.1.7) variant over several weeks. In a substudy of 589 individuals, we show that this single dose induces severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibody (NAb) responses and a sustained B and T cell response to the spike protein. NAb levels were higher after the extended dosing interval (6-14 weeks) compared with the conventional 3- to 4-week regimen, accompanied by enrichment of CD4 + T cells expressing interleukin-2 (IL-2). Prior SARS-CoV-2 infection amplified and accelerated the response. These data on dynamic cellular and humoral responses indicate that extension of the dosing interval is an effective immunogenic protocol., Competing Interests: Declaration of interests A.J.P. is Chair of the United Kingdom Department of Health and Social Care (DHSC) Joint Committee on Vaccination & Immunisation (JCVI) but does not participate in policy decisions on COVID-19 vaccines. He is a member of the WHO’s SAGE. The views expressed in this article do not necessarily represent the views of the DHSC, JCVI, or WHO. A.J.P. is chief investigator on clinical trials of Oxford University’s COVID-19 vaccine funded by NIHR. Oxford University has entered a joint COVID-19 vaccine development partnership with AstraZeneca., (Copyright © 2021 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Clostridium difficile is recognized as a frequent cause of antibiotic-associated diarrhea and colitis., Objectives: The aim of this review is to investigate the efficacy of antibiotic therapy for C. difficile-associated diarrhea (CDAD)., Search Strategy: MEDLINE (1966 to March 24, 2010), EMBASE (1980 to March 24, 2010), Cochrane Central Register of Controlled Trials and the Cochrane IBD/FBD Review Group Specialized Trials Register were searched using the following search terms: "pseudomembranous colitis and randomized trial"; "Clostridium difficile and randomized trial"; "antibiotic associated diarrhea and randomized trial"., Selection Criteria: Only randomized, controlled trials assessing antibiotic treatment for CDAD were included in the review. The following outcomes were sought: initial resolution of diarrhea; initial conversion of stool to cytotoxin and/or culture negative; recurrence of diarrhea; recurrence of fecal evidence of CDAD; patient response to cessation of prior antibiotic therapy; emergent surgery; and death., Data Collection and Analysis: Three authors independently assessed abstracts and full text articles for inclusion. The risk of bias was independently rated by two authors. For dichotomous outcomes, relative risks (RR) and 95% confidence intervals (CI) were derived from each study and summary statistics obtained when appropriate, using a fixed effects model, except where significant heterogeneity was detected, at which time a random effects model was used., Main Results: Fifteen studies (total of 1152 participants) with CDAD were included. Nine different antibiotics were investigated: vancomycin, metronidazole, fusidic acid, nitazoxanide, teicoplanin, rifampin, rifaximin, bacitracin and fidaxomicin (OPT-80). Most of the studies were active comparator studies comparing vancomycin with other antibiotics. The risk of bias was rated as high for 12 of 15 included studies. Patients with severe CDAD were often excluded from the included studies. In the only placebo-controlled trial vancomycin was found to be superior to placebo for treatment of CDAD for initial symptomatic cure. Initial symptomatic cure was achieved in 41% of vancomycin patients compared to 4% of placebo patients (1 study; 44 patients; RR 9.00; 95% CI 1.24 to 65.16). Vancomycin was significantly superior to placebo for initial bacteriologic response. Initial bacteriologic response was achieved in 45% of vancomycin patients compared to 4% of placebo patients (1 study; 44 patients; RR 10.00; 95% CI 1.40 to 71.62). The results of this study should be interpreted with caution due to the small number of patients and high risk of bias. No statistically significant differences in efficacy were found between vancomycin and metronidazole, vancomycin and fusidic acid, vancomycin and nitazoxanide, or vancomycin and rifaximin. No statistically significant differences in efficacy were found between metronidazole and nitazoxanide or metronidazole and fusidic acid. Vancomycin was significantly superior to bacitracin for initial bacteriologic response. Initial bacteriologic response was achieved in 48% of vancomycin patients compared to 25% of bacitracin patients (2 studies; 104 patients; RR 0.52; 95% CI 0.31 to 0.86). Teicoplanin, an antibiotic of limited availability and great cost, was significantly superior to vancomycin for initial bacteriologic response and cure. Initial bacteriologic response was achieved in 62% of vancomycin patients compared to 87% of teicoplanin patients (2 studies; 110 patients; RR 1.43; 95% CI 1.14 to 1.81). Bacteriologic cure was achieved in 45% of vancomycin patients compared to 82% of teicoplanin patients (2 studies; 110 patients; RR 1.82; 95% CI 1.19 to 2.78). These results should be interpreted with caution due to the small number of patients and the high risk of bias in the two studies in the pooled analysis. Teicoplanin was significantly superior to metronidazole for initial bacteriologic response. Initial bacteriologic response was achieved in 71% of metronidazole patients compared to 93% of teicoplanin patients (1 study; 59 patients; RR 0.76; 95% CI 0.60 to 0.98). This result should be interpreted with caution due to the small number of patients and high risk of bias in the study. Only one study investigated synergistic antibiotic combination, metronidazole and rifampin, and no advantage was demonstrated for the drug combination. This result should be interpreted with caution due to the small number of patients and high risk of bias in the study. Adverse events including surgery and death occurred infrequently in the included studies. There was a total of 18 deaths among 1152 patients in this systematic review. Among the studies that commented on the cause of mortality the deaths were attributed to underlying disease rather than CDAD or antibiotic treatment. One study reported a partial colectomy after failed CDAD treatment., Authors' Conclusions: Current evidence leads to uncertainty whether mild CDAD needs to be treated. The studies provide little evidence for antibiotic treatment of severe CDAD as many studies excluded these patients. Considering the two goals of therapy: improvement of the patient's clinical condition and prevention of spread of C. difficile infection to other patients, one should choose the antibiotic that brings both symptomatic cure and bacteriologic cure. A recommendation to achieve these goals cannot be made because of the small numbers of patients in the included studies and the high risk of bias in these studies, especially related to dropouts. Most of the active comparator studies found no statistically significant difference in efficacy between vancomycin and other antibiotics including metronidazole, fusidic acid, nitazoxanide or rifaximin. Teicoplanin may be an attractive choice but for its limited availability (Teicoplanin is not available in the USA) and great cost relative to the other options. More research of antibiotic treatment and other treatment modalities of CDAD is required.