ABSTRACT
We describe three cases of critical acute myositis with myocarditis occurring within 22 days of each other at a single institution, all within one month of receiving the initial cycle of the anti-PD-1 drug Pembrolizumab. Analysis of T cell receptor repertoires from peripheral blood and tissues revealed a high degree of clonal expansion and public clones between cases, with several T cell clones expanded within the skeletal muscle putatively recognising viral epitopes. All patients had recently received a COVID-19 mRNA booster vaccine prior to treatment and were positive for SARS-CoV2 Spike antibody. In conclusion, we report a series of unusually severe myositis and myocarditis following PD-1 blockade and the COVID-19 mRNA vaccination.
Subject(s)
COVID-19 , Myocarditis , MyositisABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is normally controlled by effective host immunity including innate, humoral and cellular responses. However, the trajectories and correlates of acquired immunity, and the capacity of memory responses months after infection to neutralise variants of concern - which has important public health implications - is not fully understood. To address this, we studied a cohort of 78 UK healthcare workers who presented in April to June 2020 with symptomatic PCR-confirmed infection or who tested positive during an asymptomatic screening programme and tracked virus-specific B and T cell responses longitudinally at 5-6 time points each over 6 months, prior to vaccination. We observed a highly variable range of responses, some of which - T cell interferon-gamma (IFN-γ) ELISpot, N-specific antibody waned over time across the cohort, while others (spike-specific antibody, B cell memory ELISpot) were stable. In such cohorts, antiviral antibody has been linked to protection against re-infection. We used integrative analysis and a machine-learning approach (SIMON - Sequential Iterative Modeling Over Night) to explore this heterogeneity and to identify predictors of sustained immune responses. Hierarchical clustering defined a group of high and low antibody responders, which showed stability over time regardless of clinical presentation. These antibody responses correlated with IFN-γ ELISpot measures of T cell immunity and represent a subgroup of patients with a robust trajectory for longer term immunity. Importantly, this immune-phenotype associates with higher levels of neutralising antibodies not only against the infecting (Victoria) strain but also against variants B.1.1.7 (alpha) and B.1.351 (beta). Overall memory responses to SARS-CoV-2 show distinct trajectories following early priming, that may define subsequent protection against infection and severe disease from novel variants.
Subject(s)
COVID-19ABSTRACT
ObjectivesWe investigate determinants of SARS-CoV-2 anti-spike IgG responses in healthcare workers (HCWs) following one or two doses of Pfizer-BioNTech or Oxford-AstraZeneca vaccines. MethodsHCWs participating in regular SARS-CoV-2 PCR and antibody testing were invited for serological testing prior to first and second vaccination, and 4 weeks post-vaccination if receiving a 12-week dosing interval. Quantitative post-vaccination anti-spike antibody responses were measured using the Abbott SARS-CoV-2 IgG II Quant assay (detection threshold: [≥]50 AU/ml). We used multivariable logistic regression to identify predictors of seropositivity and generalised additive models to track antibody responses over time. ResultsVaccine uptake was 80%, but less in lower-paid roles and Black, south Asian and minority ethnic groups. 3570/3610(98.9%) HCWs were seropositive >14 days post-first vaccination and prior to second vaccination, 2706/2720(99.5%) after Pfizer-BioNTech and 864/890(97.1%) following Oxford-AstraZeneca vaccines. Previously infected and younger HCWs were more likely to test seropositive post-first vaccination, with no evidence of differences by sex or ethnicity. All 470 HCWs tested >14 days after second vaccine were seropositive. Quantitative antibody responses were higher after previous infection: median(IQR) >21 days post-first Pfizer-BioNTech 14,604(7644-22,291) AU/ml vs. 1028(564-1985) AU/ml without prior infection (p<0.001). Oxford-AstraZeneca vaccine recipients had lower readings post-first dose compared to Pfizer-BioNTech, with and without previous infection, 10,095(5354-17,096) and 435(203-962) AU/ml respectively (both p<0.001 vs. Pfizer-BioNTech). Antibody responses post-second vaccination were similar to those after prior infection and one vaccine dose. ConclusionsVaccination leads to detectable anti-spike antibodies in nearly all adult HCWs. Whether differences in response impact vaccine efficacy needs further study.
ABSTRACT
Background Natural and vaccine-induced immunity will play a key role in controlling the SARS-CoV-2 pandemic. SARS-CoV-2 variants have the potential to evade natural and vaccine-induced immunity. Methods In a longitudinal cohort study of healthcare workers (HCWs) in Oxfordshire, UK, we investigated the protection from symptomatic and asymptomatic PCR-confirmed SARS-CoV-2 infection conferred by vaccination (Pfizer-BioNTech BNT162b2, Oxford-AstraZeneca ChAdOx1 nCOV-19) and prior infection (determined using anti-spike antibody status), using Poisson regression adjusted for age, sex, temporal changes in incidence and role. We estimated protection conferred after one versus two vaccinations and from infections with the B.1.1.7 variant identified using whole genome sequencing. Results 13,109 HCWs participated; 8285 received the Pfizer-BioNTech vaccine (1407 two doses) and 2738 the Oxford-AstraZeneca vaccine (49 two doses). Compared to unvaccinated seronegative HCWs, natural immunity and two vaccination doses provided similar protection against symptomatic infection: no HCW vaccinated twice had symptomatic infection, and incidence was 98% lower in seropositive HCWs (adjusted incidence rate ratio 0.02 [95%CI <0.01-0.18]). Two vaccine doses or seropositivity reduced the incidence of any PCR-positive result with or without symptoms by 90% (0.10 [0.02-0.38]) and 85% (0.15 [0.08-0.26]) respectively. Single-dose vaccination reduced the incidence of symptomatic infection by 67% (0.33 [0.21-0.52]) and any PCR-positive result by 64% (0.36 [0.26-0.50]). There was no evidence of differences in immunity induced by natural infection and vaccination for infections with S-gene target failure and B.1.1.7. Conclusion Natural infection resulting in detectable anti-spike antibodies and two vaccine doses both provide robust protection against SARS-CoV-2 infection, including against the B.1.1.7 variant.
Subject(s)
COVID-19 , Protein S DeficiencyABSTRACT
BackgroundIt is critical to understand whether infection with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) protects from subsequent reinfection. MethodsWe investigated the incidence of SARS-CoV-2 PCR-positive results in seropositive and seronegative healthcare workers (HCWs) attending asymptomatic and symptomatic staff testing at Oxford University Hospitals, UK. Baseline antibody status was determined using anti-spike and/or anti-nucleocapsid IgG assays and staff followed for up to 30 weeks. We used Poisson regression to estimate the relative incidence of PCR-positive results and new symptomatic infection by antibody status, accounting for age, gender and changes in incidence over time. ResultsA total of 12219 HCWs participated and had anti-spike IgG measured, 11052 were followed up after negative and 1246 after positive antibody results including 79 who seroconverted during follow up. 89 PCR-confirmed symptomatic infections occurred in seronegative individuals (0.46 cases per 10,000 days at risk) and no symptomatic infections in those with anti-spike antibodies. Additionally, 76 (0.40/10,000 days at risk) anti-spike IgG seronegative individuals had PCR-positive tests in asymptomatic screening, compared to 3 (0.21/10,000 days at risk) seropositive individuals. Overall, positive baseline anti-spike antibodies were associated with lower rates of PCR-positivity (with or without symptoms) (adjusted rate ratio 0.24 [95%CI 0.08-0.76, p=0.015]). Rate ratios were similar using anti-nucleocapsid IgG alone or combined with anti-spike IgG to determine baseline status. ConclusionsPrior SARS-CoV-2 infection that generated antibody responses offered protection from reinfection for most people in the six months following infection. Further work is required to determine the long-term duration and correlates of post-infection immunity.
Subject(s)
COVID-19 , Severe Acute Respiratory SyndromeABSTRACT
BackgroundSARS-CoV-2 IgG antibody measurements can be used to estimate the proportion of a population exposed or infected and may be informative about the risk of future infection. Previous estimates of the duration of antibody responses vary. MethodsWe present 6 months of data from a longitudinal seroprevalence study of 3217 UK healthcare workers (HCWs). Serial measurements of IgG antibodies to SARS-CoV-2 nucleocapsid were obtained. Bayesian mixed linear models were used to investigate antibody waning and associations with age, gender, ethnicity, previous symptoms and PCR results. ResultsIn this cohort of working age HCWs, antibody levels rose to a peak at 24 (95% credibility interval, CrI 19-31) days post-first positive PCR test, before beginning to fall. Considering 452 IgG seropositive HCWs over a median of 121 days (maximum 171 days) from their maximum positive IgG titre, the mean estimated antibody half-life was 85 (95%CrI, 81-90) days. The estimated mean time to loss of a positive antibody result was 137 (95%CrI 127-148) days. We observed variation between individuals; higher maximum observed IgG titres were associated with longer estimated antibody half-lives. Increasing age, Asian ethnicity and prior self-reported symptoms were independently associated with higher maximum antibody levels, and increasing age and a positive PCR test undertaken for symptoms with longer antibody half-lives. ConclusionIgG antibody levels to SARS-CoV-2 nucleocapsid wane within months, and faster in younger adults and those without symptoms. Ongoing longitudinal studies are required to track the long-term duration of antibody levels and their association with immunity to SARS-CoV-2 reinfection. SummarySerially measured SARS-CoV-2 anti-nucleocapsid IgG titres from 452 seropositive healthcare workers demonstrate levels fall by half in 85 days. From a peak result, detectable antibodies last a mean 137 days. Levels fall faster in younger adults and following asymptomatic infection.
ABSTRACT
Thresholds for SARS-CoV-2 antibody assays have typically been determined using samples from symptomatic, often hospitalised, patients. Assay performance following mild/asymptomatic infection is unclear. We assessed IgG responses in asymptomatic healthcare workers with a high pre-test probability of Covid-19, e.g. 807/9292(8.9%) reported loss of smell/taste. The proportion reporting anosmia/ageusia increased at antibody titres below diagnostic thresholds for both an in-house ELISA and the Abbott Architect chemiluminescent microparticle immunoassay (CMIA): 424/903(47%) reported anosmia/ageusia with a positive ELISA, 59/387(13.2%) with high-negative titres, and 324/7943(4.1%) with low-negative results. Adjusting for the proportion of staff reporting anosmia/ageusia suggests the sensitivity of both assays is lower than previously reported: Oxford ELISA 90.8% (95%CI 86.1-92.1%) and Abbott CMIA 80.9% (77.5-84.3%). However, the sensitivity may be lower if some anosmia/ageusia in those with low-negative titres is Covid-19-associated. Samples from individuals with mild/asymptomatic infection should be included in SARS-CoV-2 immunoassay evaluations. Reporting equivocal SARS-CoV-2 antibody results should be considered.
Subject(s)
COVID-19 , Olfaction Disorders , AgeusiaABSTRACT
Background: Laboratory diagnosis of SARS-CoV-2 infection (the cause of COVID-19) uses PCR to detect viral RNA (vRNA) in respiratory samples. SARS-CoV-2 RNA has also been detected in other sample types, but there is limited understanding of the clinical or laboratory significance of its detection in blood. Methods: We undertook a systematic literature review to assimilate the evidence for the frequency of vRNA in blood, and to identify associated clinical characteristics. We performed RT-PCR in serum samples from a UK clinical cohort of acute and convalescent COVID-19 cases (n=212), together with convalescent plasma samples collected by NHS Blood and Transplant (NHSBT) (n=111 additional samples). To determine whether PCR-positive blood samples could pose an infection risk, we attempted virus isolation from a subset of RNA-positive samples. Results: We identified 28 relevant studies, reporting SARS-CoV-2 RNA in 0-76% of blood samples; pooled estimate 10% (95%CI 5-18%). Among serum samples from our clinical cohort, 27/212 (12.7%) had SARS-CoV-2 RNA detected by RT-PCR. RNA detection occurred in samples up to day 20 post symptom onset, and was associated with more severe disease (multivariable odds ratio 7.5). Across all samples collected [≥]28 days post symptom onset, 0/143 (0%, 95%CI 0.0-2.5%) had vRNA detected. Among our PCR-positive samples, cycle threshold (ct) values were high (range 33.5-44.8), suggesting low vRNA copy numbers. PCR-positive sera inoculated into cell culture did not produce any cytopathic effect or yield an increase in detectable SARS-CoV-2 RNA. Conclusions: vRNA was detectable at low viral loads in a minority of serum samples collected in acute infection, but was not associated with infectious SARS-CoV-2 (within the limitations of the assays used). This work helps to inform biosafety precautions for handling blood products from patients with current or previous COVID-19.
Subject(s)
COVID-19 , Severe Acute Respiratory Syndrome , Acute DiseaseABSTRACT
Objective To ascertain the diagnostic performance of faecal immunochemical test (FIT) in symptomatic primary care patients, to provide objective data on which to base referral guidelines. Design Stool samples from routine primary care practice in Oxfordshire, UK were analysed using the HM-JACKarc FIT method between March 2017 to March 2020. Clinical details described on the test request were recorded. Patients were followed up for up-to 36 months in linked hospital records for evidence of benign and serious (colorectal cancer, high-risk adenomas and bowel inflammation) colorectal disease. The diagnostic accuracy of FIT is reported by gender, age, and FIT threshold. Results In 9,896 adult patients with at least 6 months of follow-up, a FIT result ≥10 μg/g had an overall sensitivity for colorectal cancer of 90.5% (95% CI 84.9%-96.1%), women 90.0 (80.7-99.3), men 90.8 (83.7-97.8); overall specificity 91.3 (90.8-91.9), women 92.4 (91.8-93.1), men 89.8 (88.8-90.7); overall Positive Predictive Value (PPV) 10.1 (8.15-12.0), women 7.64 (5.24-10.0), men 12.5 (9.52-15.5)); and an overall Negative Predictive Value (NPV) 99.9 (99.8-100.0), women 99.8 (99.7-100.), men 99.9 (99.9-100.0). The PPV and specificity of FIT were higher for serious colorectal disease combined and the sensitivity and NPV were lower than for colorectal cancer alone. The Area Under the Curve (AUC) for all patients did not change substantially by increasing the minimum age of testing. In this population, 10% would be further investigated to detect 91% of the cancers at 10ug/g and 3% further investigated to detect 54% of the cancers at 150ug/g. The number needed to scope to detect one cancer was ten using FIT at 10ug/g. Conclusion A FIT threshold of 10 µg/g is appropriate to triage adult patients presenting to primary care with symptoms of serious colorectal disease. FIT may provide an appropriate approach to reprioritising patients colorectal cancer symptoms whose tests have been delayed by the COVID-19 pandemic. What is already known on this subject? Faecal Immunochemical Testing (FIT) is recommended by NICE to triage symptomatic primary care patients into further investigation for serious colorectal disease, including colorectal cancer. Almost no real-world data exists documenting the diagnostic accuracy of low FIT thresholds associated with colorectal cancer or serious colorectal disease in primary care with symptoms of colorectal cancer. What are the new findings? In 9,896 consecutive FITs submitted by English General Practitioners to a large English laboratory, using a threshold of 10ug/g, FIT had a sensitivity and specificity of 91% for colorectal cancer, a sensitivity of 53% and a specificity of 92% for serious colorectal disease. Of the population tested with FIT, 10% would be further investigated to detect 91% of the cancers at 10ug/g, 4% would be further investigated to detect 74% of the cancers at 50ug/g, and 3% further investigated to detect 54% of the cancers at 150ug/g. How might it impact on clinical practice in the foreseeable future? Low threshold FIT could be used as a triage test without overburdening endoscopy resources, supporting widespread implementation of the NICE recommendations for its use in low-risk patients in primary care. FIT may be an effective test for re-prioritizing patients whose endoscopy test have been deferred due to the COVID-19 pandemic to match available endoscopy resources to those at highest risk of colorectal cancer.
Subject(s)
COVID-19 , Neoplasms , Adenoma , Inflammation , Colorectal NeoplasmsABSTRACT
Aims To determine analytical capabilities of a commonly used faecal immunochemical test (FIT) to detect haemoglobin (Hb) in the context of NICE guidance DG30, and the likely use of FIT to reprioritise patients delayed by the COVID-19 pandemic. Methods Data obtained from independent verification studies and clinical testing of the HM-JACKarc FIT method in routine primary care practice were analysed to derive analytical performance characteristics. Results Detection capabilities for the FIT method were 0.5 µg/g (limit of blank), 1.1 (limit of detection) and 15.0 µg/g (limit of quantification). 31 of 33 (94%) non-homogenised specimens analysed in triplicate were consistently categorised relative to 10 µg/g compared to all 33 (100%) homogenised specimens. Imprecision in non-homogenised specimens was higher (median 27.8%, (range 20.5% - 48.6%)) than in homogenised specimens (10.2%, (7.0 to 13.5%)). Considerable variation was observed in sequential clinical specimens from individual patients but no positive or negative trend in specimen degradation was observed (p=0.26). Conclusions The FIT method is capable of detecting Hb at concentrations well below the DG30 threshold of 10 µg/g. However, total imprecision is considerable when including sampling variation. Binary categorisation against a single defined threshold above and below 10 µg/g was more consistent and improved following specimen homogenisation. This approach may be more appropriate when reporting results for symptomatic patients tested in primary care, including those who have had definitive investigation delayed by the COVID-19 pandemic and need to be re-prioritised. Key Messages Faecal immunochemical testing (FIT) is increasingly used to detect blood at low haemoglobin (Hb) concentrations in specimens from symptomatic primary care patients but the analytical characteristics in this context have not been fully documented. A commonly used FIT method showed good capability in a routine UK clinical setting to detect Hb at the NICE recommended threshold of 10µg/g. Imprecision estimates were considerable when sampling was considered, even above the limit of quantification of 15 µg/g. Analytical variability appears too high for reliable reporting of quantitative Hb concentrations: reporting positive or negative results around a threshold of 10µg/g appears more appropriate after sample homogenisation. Dichotomous FIT reporting is likely to be an important tool to risk stratify patients with lower GI cancer symptoms who have had their test deferred due to the COVID-19 pandemic