Wastewater genomic surveillance tracks the spread of the SARS-CoV-2 Omicron variant across England (preprint)

Background Many countries have moved into a new stage of managing the SARS-CoV-2 pandemic with minimal restrictions and reduced testing in the population, leading to reduced genomic surveillance of virus variants in individuals. Wastewater-based epidemiology (WBE) can provide an alternative means of tracking virus variants in the population but is lacking verifications of its comparability to individual testing data. Methods We analysed more than 19,000 samples from 524 wastewater sites across England at least twice a week between November 2021 and February 2022, capturing sewage from >70% of the English population. We used amplicon-based sequencing and the phylogeny based de-mixing tool Freyja to estimate SARS-CoV-2 variant frequencies and compared these to the variant dynamics observed in individual testing data from clinical and community settings. Findings We show that wastewater data can reconstruct the spread of the Omicron variant across England since November 2021 in close detail and aligns closely with epidemiological estimates from individual testing data. We also show the temporal and spatial spread of Omicron within London. Our wastewater data further reliably track the transition between Omicron subvariants BA1 and BA2 in February 2022 at regional and national levels. Interpretation Our demonstration that WBE can track the fast-paced dynamics of SARS-CoV-2 variant frequencies at a national scale and closely match individual testing data in time shows that WBE can reliably fill the monitoring gap left by reduced individual testing in a more affordable way.

Analysis of the ARTIC V4 and V4.1 SARS-CoV-2 primers and their impact on the detection of Omicron BA.1 and BA.2 lineage defining mutations (preprint)

The ARTIC protocol uses a multiplexed PCR approach with two primer pools tiling the entire SARS-CoV-2 genome. Primer pool updates are necessary for accurate amplicon sequencing of evolving SARS-CoV-2 variants with novel mutations. The suitability of the ARTIC V4 and updated V4.1 primer scheme was assessed using whole genome sequencing of Omicron from clinical samples using Oxford Nanopore Technology. Analysis of Omicron BA.1 genomes revealed that 93.22% of clinical samples generated improved genome coverage at 50x read depth with V4.1 primers when compared to V4 primers. Additionally, the V4.1 primers improved coverage of BA.1 across amplicons 76 and 88, which resulted in the detection of the variant defining mutations G22898A, A26530G and C26577G. The Omicron BA.2 sub-variant (VUI-22JAN-01) replaced BA.1 as the dominant variant by March 2022, and analysis of 168 clinical samples showed reduced coverage across amplicons 15 and 75. Upon further interrogation of primer binding sites, a mutation at C4321T (present in 163/168, 97% of 30 samples) was identified as a possible cause of complete dropout of amplicon 15. Furthermore, two mutations were identified within the primer binding regions for amplicon 75: A22786C (present in 90% of samples) and C22792T (present in 12.5% of samples). Together, these mutations may result in reduced coverage of amplicon 75 and further primer updates would allow the identification of the two BA.2 defining mutations present in amplicon 75; A22688G and T22679C. This work highlights the need for ongoing surveillance of primer matches as circulating variants evolve and change.

Multi-site validation of an amplicon-based sequencing approach for human monkeypox virus (preprint)

The 2022 multi-country monkeypox outbreak concurrent with the ongoing COVID-19 pandemic has further highlighted the need for genomic surveillance and pathogen whole genome sequencing. While metagenomic sequencing approaches have been used to sequence many of the early human monkeypox virus infections, these methods are resource intensive and require samples with high viral DNA concentrations. Given the atypical clinical presentation of cases associated with the current outbreak and uncertainty regarding viral load across both the course of infection and anatomical body sites, there is an urgent need for a more sensitive and broadly applicable sequencing approach. Amplicon-based sequencing (PrimalSeq) was initially developed for sequencing of Zika virus, and later adapted as the main sequencing approach for SARS-CoV-2. Here, we used PrimalScheme to develop a primer scheme for human monkeypox virus that can be used with many sequencing and bioinformatics pipelines implemented during the COVID-19 pandemic. We sequenced clinical samples that tested presumptive positive for monkeypox virus with amplicon-based and metagenomic sequencing approaches. Upon comparison, we found notably higher genome coverage across the virus genome, particularly in higher PCR cycle threshold (lower DNA titer) samples, with minimal amplicon drop-outs, in using the amplicon-based sequencing approach. By sending out primer pool aliquots to laboratories across the United States and internationally, we validated the primer scheme in 12 public health laboratories with their established Illumina or Oxford Nanopore Technologies sequencing workflows and with different sample types across a range of Ct values. Our findings suggest that amplicon-based sequencing increases the success rate across a wider range of viral DNA concentrations, with the PCR Ct value threshold at which laboratories were able to achieve 80% genome coverage at 10X ranging between Ct 25-33. Therefore, it increases the number of samples where near-complete genomes can be generated and it provides a cost-effective and widely applicable alternative to metagenomics for continued human monkeypox virus genomic surveillance. Importantly, we show that the human monkeypox virus primer scheme can be used with currently implemented amplicon-based SARS-CoV-2 sequencing workflows, with minimal change to the protocol.

Genomic Investigations of Acute Hepatitis of Unknown Aetiology in Children (preprint)

Since the first reports of hepatitis of unknown aetiology occurring in UK children, over 1000 cases have been reported worldwide, including 268 cases in the UK, with the majority younger than 6 years old. Using genomic, proteomic and immunohistochemical methods, we undertook extensive investigation of 28 cases and 136 control subjects. In five cases who underwent liver transplantation, we detected high levels of adeno-associated virus 2 (AAV2) in the explanted livers. AAV2 was also detected at high levels in blood from 10/11 non-transplanted cases. Low levels of Adenovirus (HAdV) and Human Herpesvirus 6B (HHV-6B), both of which enable AAV2 lytic replication, were also found in the five explanted livers and blood from 15/17 and 6/9 respectively, of the 23 non-transplant cases tested. In contrast, AAV2 was detected at low titre in 6/100 whole bloods from child controls from cohorts with presence or absence of hepatitis and/or adenovirus infection. Our data show an association of AAV2 at high titre in blood or liver tissue, with unexplained hepatitis in children infected in the recent HAdV-F41 outbreak. We were unable to find evidence by electron microscopy, immunohistochemistry or proteomics of HAdV or AAV2 viral particles or proteins in explanted livers, suggesting that hepatic pathology is not due to direct lytic infection by either virus. The potential that AAV2, although not previously associated with disease, may, together with HAdV-F41 and/or HHV-6, be causally implicated in the outbreak of unexplained hepatitis, requires further investigation.

Structural epitope profiling identifies antibodies associated with critical COVID-19 and long COVID (preprint)

Antibodies can have beneficial, neutral, or harmful effects so resolving an antibody repertoire to its target epitopes may explain heterogeneity in susceptibility to infectious disease. However, the three-dimensional nature of antibody-epitope interactions limits discovery of important targets. We describe and experimentally validated a computational method and synthetic biology pipeline for identifying structurally stable and functionally important epitopes from the SARS-CoV-2 proteome. We identify patterns of antibodies associated with immunopathology, including a non-isotype switching IgM response to a membrane protein epitope strongly associated with severe COVID-19 (adjusted OR 72.14, 95% CI: 9.71 - 1300.15). We suggest the mechanism is T independent B cell activation and identify persistence (> 1 year) of this response in individuals with long COVID particularly affected by fatigue and depression. These findings may have implications for the ongoing medical and public health response to the pandemic.

Inconsistent directions of change in case severity across successive SARS-CoV-2 variant waves suggests an unpredictable future (preprint)

ObjectiveTo determine how the severity of successively dominant SARS-CoV-2 variants changed over the course of the COVID-19 pandemic. DesignRetrospective cohort analysis. SettingCommunity- and hospital-sequenced COVID-19 cases in the NHS Greater Glasgow and Clyde (NHS GG&C) Health Board. ParticipantsAll sequenced non-nosocomial adult COVID-19 cases in NHS GG&C infected with the relevant SARS-CoV-2 lineages during analysis periods. B.1.177/Alpha: 1st November 2020 - 30th January 2021 (n = 1640). Alpha/Delta: 1st April - 30th June 2021 (n = 5552). AY.4.2 Delta/non-AY.4.2 Delta: 1st July - 31st October 2021 (n = 9613). Non-AY.4.2 Delta/Omicron: 1st - 31st December 2021 (n = 3858). Main outcome measuresAdmission to hospital, ICU, or death within 28 days of positive COVID-19 test ResultsFor B.1.177/Alpha, 300 of 807 B.1.177 cases were recorded as hospitalised or worse, compared to 232 of 833 Alpha cases. After adjustment, the cumulative odds ratio was 1.51 (95% CI: 1.08-2.11) for Alpha versus B.1.177. For Alpha/Delta, 113 of 2104 Alpha cases were recorded as hospitalised or worse, compared to 230 of 3448 Delta cases. After adjustment, the cumulative odds ratio was 2.09 (95% CI: 1.42-3.08) for Delta versus Alpha. For non-AY.4.2 Delta/AY.4.2 Delta, 845 of 8644 non-AY.4.2 Delta cases were recorded as hospitalised or worse, compared to 101 of 969 AY.4.2 Delta cases. After adjustment, the cumulative odds ratio was 0.99 (95% CI: 0.76-1.27) for AY.4.2 Delta versus non-AY.4.2 Delta. For non-AY.4.2 Delta/Omicron, 30 of 1164 non-AY.4.2 Delta cases were recorded as hospitalised or worse, compared to 26 of 2694 Omicron cases. After adjustment, the median cumulative odds ratio was 0.49 (95% CI: 0.22-1.06) for Omicron versus non-AY.4.2 Delta. ConclusionsThe direction of change in disease severity between successively emerging SARS-CoV-2 variants of concern was inconsistent. This heterogeneity demonstrates that severity associated with future SARS-CoV-2 variants is unpredictable.

Scottish COVID CAncer iMmunity Prevalence (SCCAMP) - a longitudinal study of patients with cancer receiving active anti-cancer treatment during the COVID-19 pandemic (preprint)

Background Cancer and systemic anti-cancer treatment (SACT) have been identified as possible risk factors for infection and related severe illness associated with SARS-CoV-2 virus as a consequence of immune suppression. The Scottish COVID CAncer iMmunity Prevalence (SCCAMP) study aims to characterise the incidence and outcomes of SARS-Cov-2 infection in patients undergoing active anti-cancer treatment during the COVID-19 pandemic and their antibody response following vaccination. Patients and Methods Eligible patients were those attending secondary care for active anti-cancer treatment for a solid tumour. Blood samples were taken for total SARS-CoV-2 antibody assay (Siemens) at baseline and after 1.5, 3, 6 and 12 months. Data on COVID-19 infection, vaccination, cancer type, treatment and outcome was obtained from routine electronic health records. Results The study recruited 766 eligible participants between 28th May 2020 and 31st October 2021. The median age was 62.7 years, and 66.5% were female. Most received cytotoxic chemotherapy (79%), with the remaining 14% receiving immunotherapy and 7% receiving another form of anti-cancer therapy (radiotherapy, other systemic anti-cancer treatment). 48 (6.3%) tested positive for SARS-CoV-2 by PCR during the study period. The overall infection rate matched that of the age-matched local general population until May 2021, after which population levels appeared higher. Antibody testing detected additional evidence of infection prior to vaccination, taking the total number to 58 (7.6%). There was no significant difference in SARS-CoV-2 PCR positive test rates based on type of anti-cancer treatment. Mortality proportion was similar between those who died within 90 days of a positive SARS-CoV-2 PCR and those with no positive PCR (10.4% vs 10.6%). Death from all causes was lowest among vaccinated patients, and of the patients who had a positive SARS-CoV-2 PCR at any time, all of those who died during the study period were unvaccinated. Multivariate analysis correcting for age, gender, socioeconomic status, comorbidities and number of previous medications revealed that vaccination was associated with a significantly lower infection rate regardless of treatment with chemotherapy or immunotherapy with hazard ratios of 0.307 (95% CI 0.144-0.6548) or 0.314 (95% CI 0.041-2.367) in vaccinated patients respectively. Where antibody data was available, 96.3% of patients successfully raised SARS-CoV-2 antibodies at a time point after vaccination. This was unaffected by treatment type. Conclusion SCCAMP provides real-world evidence that patients with cancer undergoing SACT have a high antibody response and protection from SARS-CoV-2 infection following COVID-19 vaccination.

User acceptability of saliva and gargle samples for identifying COVID-19 positive high-risk workers (preprint)

Throughout the COVID-19 pandemic nasopharyngeal or nose/throat swabs (NTS) have been the primary approach for collecting patient samples for the subsequent detection of viral RNA. However, this procedure, if undertaken correctly, can be unpleasant and therefore deters individuals from providing high quality samples. To overcome these limitations other modes of sample collection have been explored. In a cohort of frontline healthcare workers we have compared saliva and gargle samples to gold-standard NTS. 93% of individuals preferred providing saliva or gargle samples, with little sex-dependent variation. Viral titres collected in samples were analysed using standard methods and showed that gargle and saliva were similarly comparable for identifying COVID-19 positive individuals compared to NTS (92% sensitivity; 98% specificity). We suggest that gargle and saliva collection are viable alternatives to NTS swabs and may encourage testing to provide better disease diagnosis and population surveillance.

The hyper-transmissible SARS-CoV-2 Omicron variant exhibits significant antigenic change, vaccine escape and a switch in cell entry mechanism (preprint)

Vaccination-based exposure to spike protein derived from early SARS-CoV-2 sequences is the key public health strategy against COVID-19. Successive waves of SARS-CoV-2 infections have been characterised by the evolution of highly mutated variants that are more transmissible and that partially evade the adaptive immune response. Omicron is the fifth of these Variants of Concern (VOCs) and is characterised by a step change in transmission capability, suggesting significant antigenic and biological change. It is characterised by 45 amino acid substitutions, including 30 changes in the spike protein relative to one of the earliest sequences, Wuhan-Hu-1, of which 15 occur in the receptor-binding domain, an area strongly associated with humoral immune evasion. In this study, we demonstrate both markedly decreased neutralisation in serology assays and real-world vaccine effectiveness in recipients of two doses of vaccine, with efficacy partially recovered by a third mRNA booster dose. We also show that immunity from natural infection (without vaccination) is more protective than two doses of vaccine but inferior to three doses. Finally, we demonstrate fundamental changes in the Omicron entry process in vitro, towards TMPRSS2-independent fusion, representing a major shift in the replication properties of SARS-CoV-2. Overall, these findings underlie rapid global transmission and may alter the clinical severity of disease associated with the Omicron variant.

Evaluation of SARS-CoV-2 Antibody Point of Care Devices in the Laboratory and Clinical Setting (preprint)

SARS-CoV-2 Antibody tests have been marketed to diagnose previous SARS-CoV-2 infection and as a test of immune status. There is a lack of evidence on the performance and clinical utility of these tests. We aimed to carry out an evaluation of 14 point of care (POC) SARS-CoV-2 antibody tests. Serum from participants with previous RT-PCR (Real-Time Polymerase chain reaction) confirmed SARS-CoV-2 infection and pre-pandemic controls were used to determine specificity and sensitivity of each POC device. Changes in sensitivity with increasing time from infection were determined on a cohort of participants. Corresponding neutralising antibody status was measured to establish whether the detection of antibodies by the POC device correlated with immune status. Paired capillary and serum samples were collected to ascertain whether POC devices performed comparably on capillary samples. Sensitivity and specificity varied between the POC devices and in general did not meet the manufacturers reported performance characteristics signifying the importance of independent evaluation of these tests. The sensitivity peaked at >20 days following symptoms onset however sensitivity of 3 POC devices evaluated at extended time points showed that sensitivity declined with time and this was particularly marked at >140 days post infection onset. This is relevant if the tests are to be used for sero-prevelence studies. Neutralising antibody data showed positive antibody results on POC devices did not necessarily confer high neutralising antibody titres and these POC devices cannot be used to determine immune status to the SARS-CoV-2 virus. Comparison of paired serum and capillary results showed that there was a decline in sensitivity using capillary blood. This has implications in the utility of the test as they are designed to be used on capillary blood by the general population.

Genomics-informed outbreak investigations of SARS-CoV-2 using civet (preprint)

The scale of data produced during the SARS-CoV-2 pandemic has been unprecedented, with more than 5 million sequences shared publicly at the time of writing. This wealth of sequence data provides important context for interpreting local outbreaks. However, placing sequences of interest into national and international context is difficult given the size of the global dataset. Often outbreak investigations and genomic surveillance efforts require running similar analyses again and again on the latest dataset and producing reports. We developed civet (cluster investigation and virus epidemiology tool) to aid these routine analyses and facilitate virus outbreak investigation and surveillance. Civet can place sequences of interest in the local context of background diversity, resolving the query into different 'catchments' and presenting the phylogenetic results alongside metadata in an interactive, distributable report. Civet can be used on a fine scale for clinical outbreak investigation, for local surveillance and cluster discovery, and to routinely summarise the virus diversity circulating on a national level. Civet reports have helped researchers and public health bodies feedback genomic information in the appropriate context within a timeframe that is useful for public health.

Randomised Controlled Trial of Intravenous Nafamostat Mesylate in COVID Pneumonitis: Phase 1b/2a Experimental Study to Investigate Safety, Pharmacokinetics and Pharmacodynamics (preprint)

Background: Many repurposed drugs have progressed rapidly to Phase 2 and 3 trials in COVID19 without characterisation of Pharmacokinetics /Pharmacodynamics including safety data. One such drug is Nafamostat Mesylate.Methods: We present the findings of a phase Ib/II open label, platform randomised controlled trial of intravenous Nafamostat in hospitalised patients with confirmed COVID-19 pneumonitis. Patients were assigned randomly to standard of care (SoC), Nafamostat or an alternative therapy. Nafamostat was administered as an intravenous infusion at a dose of 0.2mg/kg/hour for a maximum of seven days. The analysis population included those who received any dose of the trial drug and all patients randomised to SoC.Results: Data is reported from 42 patients, 21 of which were randomly assigned to receive intravenous Nafamostat. 78% of Nafamostat-treated patients experienced at least one AE compared to 57% of the SoC group. The Nafamostat group developed significantly higher plasma creatinine levels and had a lower number of oxygen free days (posterior mean difference 10.57 micromol/L, 95% HPD interval 2.43 - 18.92, rate ratio 0.55- 95% HPD interval 0.31- 0.99 respectively). There were no other statistically significant differences in endpoints between Nafamostat and SoC. PK data demonstrated that intravenous Nafamostat was rapidly broken down to inactive metabolites. We observed no significant anticoagulant effects in thromboelastometry. Participants in the Nafamostat group had higher D-Dimers.Interpretation: In hospitalised patients with COVID-19, we did not observe evidence of anti-inflammatory, anticoagulant or antiviral activity with intravenous Nafamostat. Further evaluation of Nafamostat delivered via a different route may be warranted.Clinical Trial Registration Details: This trial has been registered on ISRCTN (https://www.isrctn.com/) ISRCTN14212905, and Clinicaltrials.gov (https://www.clinicaltrials.gov/) NCT04473053. Funding Information: DEFINE was funded by LifeArc (an independent medical research charity under the STOPCOVID award to the University of Edinburgh. We also thank the Oxford University COVID-19 Research Response Fund (BRD00230).Declaration of Interests: The authors report no conflict of interests.Ethics Approval Statement: The DEFINE trial has received full ethical approval from Scotland A REC (20/SS/0066), the MHRA (EudraCT 2020-002230-32) and NHS Lothian. Written informed consent was taken by trial clinicians prior to any trial procedures being performed. If a patient lacked capacity, consent could be provided by their next of kin.

TITLE: Randomised Controlled Trial of Intravenous Nafamostat Mesylate in COVID pneumonitis: Phase 1b/2a Experimental Study to Investigate Safety, Pharmacokinetics and Pharmacodynamics (preprint)

Despite the success of vaccines and selected repurposed treatments, COVID-19 is likely to remain a global health problem and further chemotherapeutics are required. Many repurposed drugs have progressed rapidly to Phase 2 and 3 trials without characterisation of Pharmacokinetics (PK)/Pharmacodynamics (PD) including safety in COVID-19. One such drug is Nafamostat Mesylate (Nafamostat), a synthetic serine protease inhibitor with anticoagulant and anti-inflammatory properties. Preclinical data has demonstrated that it is has potent antiviral activity against SARS-CoV-2 by directly inhibiting the transmembrane protease serine 2 (TMPRSS2) dependent stage of host cell entry. Methods: We present the findings of a phase Ib/II open label, platform randomised controlled trial (RCT), exploring the safety of intravenous Nafamostat in hospitalised patients with confirmed COVID-19 pneumonitis. Patients were assigned randomly to standard of care (SoC), Nafamostat or an alternative therapy. Secondary endpoints included clinical endpoints such as number of oxygen free days and clinical improvement/ deterioration, PK/PD, thromboelastometry, D Dimers, cytokines, immune cell flow cytometry and viral load. Results: Data is reported from 42 patients, 21 of which were randomly assigned to receive intravenous Nafamostat. The Nafamostat group developed significantly higher plasma creatinine levels, more adverse events and a lower number of oxygen free days. There were no other statistically significant differences in the primary or secondary endpoints between Nafamostat and SoC. PK data demonstrated that intravenous Nafamostat was rapidly broken down to inactive metabolites. We observed an antifibrinolytic profile, and no significant anticoagulant effects in thromboelastometry. Participants in the Nafamostat group had higher D Dimers compared to SoC. There were no differences in cytokine profile and immune cell phenotype and viral loads between the groups. Conclusion In hospitalised patients with COVID-19, we did not observe evidence of anti-inflammatory, anticoagulant or antiviral activity with intravenous Nafamostat. Given the number of negative trials with repurposed drugs, our experimental medicine trial highlights the value of PK/PD studies prior to selecting drugs for efficacy trials. Given the mechanism of action, further evaluation of Nafamostat delivered via a different route may be warranted. This trial demonstrates the importance of experimental trials in new disease entities such as COVID-19 prior to selecting drugs for larger trials.

The SARS-CoV-2 Alpha variant is associated with increased clinical severity of disease (preprint)

BackgroundThe B.1.1.7 (Alpha) SARS-CoV-2 variant of concern was associated with increased transmission relative to other variants present at the time of its emergence and several studies have shown an association between the B.1.1.7 lineage infection and increased 28-day mortality. However, to date none have addressed the impact of infection on severity of illness or the need for oxygen or ventilation. MethodsIn this prospective clinical cohort sub-study of the COG-UK consortium, 1475 samples from hospitalised and community cases collected between the 1st November 2020 and 30th January 2021 were collected. These samples were sequenced in local laboratories and analysed for the presence of B.1.1.7-defining mutations. We prospectively matched sequence data to clinical outcomes as the lineage became dominant in Scotland and modelled the association between B.1.1.7 infection and severe disease using a 4-point scale of maximum severity by 28 days: 1. no support, 2. oxygen, 3. ventilation and 4. death. Additionally, we calculated an estimate of the growth rate of B.1.1.7-associated infections following introduction into Scotland using phylogenetic data. ResultsB.1.1.7 was responsible for a third wave of SARS-CoV-2 in Scotland, and rapidly replaced the previously dominant second wave lineage B.1.177) due to a significantly higher transmission rate ([~]5 fold). Of 1475 patients, 364 were infected with B.1.1.7, 1030 with B.1.177 and 81 with other lineages. Our cumulative generalised linear mixed model analyses found evidence (cumulative odds ratio: 1.40, 95% CI: 1.02, 1.93) of a positive association between increased clinical severity and lineage (B.1.1.7 versus non-B.1.1.7). Viral load was higher in B.1.1.7 samples than in non-B.1.1.7 samples as measured by cycle threshold (Ct) value (mean Ct change: -2.46, 95% CI: -4.22, -0.70). ConclusionsThe B.1.1.7 lineage was associated with more severe clinical disease in Scottish patients than co-circulating lineages. FundingCOG-UK is supported by funding from the Medical Research Council (MRC) part of UK Research & Innovation (UKRI), the National Institute of Health Research (NIHR) and Genome Research Limited, operating as the Wellcome Sanger Institute. Funding was also provided by UKRI through the JUNIPER consortium (grant number MR/V038613/1). Sequencing and bioinformatics support was funded by the Medical Research Council (MRC) core award (MC UU 1201412).

Longitudinal variation in SARS-CoV-2 antibody levels and emergence of viral variants: implications for the ability of serological assays to predict immunity. (preprint)

Background Serological assays are being deployed to monitor antibody responses in SARS-CoV-2 convalescents and vaccine recipients. There is a need to determine whether such assays can predict immunity, as antibody levels wane and viral variants emerge. Methods We measured antibodies in a cohort of SARS-CoV-2 infected patients using several high-throughput serological tests and functional neutralization assays. The effects of time and spike protein sequence variation on the performance and predictive value of the various assays was assessed. Findings Neutralizing antibody titers decreased over the first few months post-infection but stabilized thereafter, at about 30% of the level observed shortly after infection. Serological assays commonly used to measure antibodies against SARS-CoV-2 displayed a range of sensitivities that declined to varying extents over time. Quantitative measurements generated by serological assays based on the spike protein were better at predicting neutralizing antibody titers than assays based on nucleocapsid, but performance was variable and manufacturer positivity thresholds were not able to predict the presence or absence of detectable neutralizing activity. Even though there was some deterioration in correlation between serological measurements and functional neutralization activity, some assays maintained an ability to predict neutralizing titers, even against variants of concern. Interpretation The ability of high throughput serological assays to predict neutralizing antibody titers is likely crucial for evaluation of immunity at the population scale. These data will facilitate the selection of the most suitable assays as surrogates of functional neutralizing activity and suggest that such measurements may have utility in clinical practice.

A prospective diagnostic study to measure the accuracy of detection of SARS-CoV-2 Variants Of Concern (VOC) utilising a novel RT-PCR GENotyping algorithm in an In silico Evaluation (VOC-GENIE) (preprint)

Background SARS-CoV-2 variants of concern (VOCs) have been associated with higher rate of transmission, and evasion of immunisation and antibody therapeutics. Variant sequencing is widely utilized in the UK. However, only 0.5% (~650k) of the 133 million cumulative positive cases worldwide were sequenced (in GISAID) on 08 April 2021 with 97% from Europe and North America and only ~0.25% (~320k) were variant sequences. This may be due to the lack of availability, high cost, infrastructure and expert staff required for sequencing. Public health decisions based on a non-randomised sample of 0.5% of the population may be insufficiently powered, and subject to sampling bias and systematic error. In addition, sequencing is rarely available in situ in a clinically relevant timeframe and thus, is not currently compatible with diagnosis and treatment patient care pathways. Therefore, we investigated an alternative approach using polymerase chain reaction (PCR) genotyping to detect the key single nucleotide polymorphisms (SNPs) associated with increased transmission and immune evasion in SARS-CoV-2 variants. Methods We investigated the utility of SARS-CoV-2 SNP detection with a panel of PCR-genotyping assays in a large data set of 640,482 SARS-CoV-2 high quality, full length sequences using a prospective in silico trial design and explored the potential impact of rapid in situ variant testing on the COVID-19 diagnosis and treatment patient pathway. Results Five SNPs were selected by screening the published literature for a reported association with increased transmission and / or immune evasion. 344881 sequences contained one or more of the five SNPs. This algorithm of SNPs was found to be able to identify the four variants of concern (VOCs) and sequences containing the E484K and L452R escape mutations. Interpretation The in silico analysis suggest that the key mutations and variants of SARS-CoV-2 may be reliably detected using a focused algorithm of biologically relevant SNPs. This highlights the potential for rapid in situ PCR genotyping to compliment or replace sequencing or to be utilized instead of sequences in settings where sequencing is not feasible, accessible or affordable. Rapid detection of variants with in situ PCR genotyping may facilitate a more effective COVID-19 diagnosis and treatment patient pathway.

A Prospective Diagnostic Study to Measure the Accuracy of Detection of SARS-CoV-2 Variants Of Concern (VOC) Utilising a Novel RT-PCR GENotyping Algorithm in an in silico Evaluation (VOC-GENIE) (preprint)

Background: SARS-CoV-2 variants of concern (VOCs) have been associated with higher rate of transmission, and evasion of immunisation and antibody therapeutics. Variant sequencing is widely utilized in the UK. However, only 0.5% (~650k) of the 133 million cumulative positive cases worldwide were sequenced (in GISAID) on 08 April 2021 with 97% from Europe and North America and only ~0.25% (~320k) were variant sequences. This may be due to the lack of availability, high cost, infrastructure and expert staff required for sequencing. Public health decisions based on a non-randomised sample of 0.5% of the population may be insufficiently powered, and subject to sampling bias and systematic error. In addition, sequencing is rarely available in situ in a clinically relevant timeframe and thus, is not currently compatible with diagnosis and treatment patient care pathways. Therefore, we investigated an alternative approach using polymerase chain reaction (PCR) genotyping to detect the key single nucleotide polymorphisms (SNPs) associated with increased transmission and immune evasion in SARS-CoV-2 variants.Methods: We investigated the utility of SARS-CoV-2 SNP detection with a panel of PCR-genotyping assays in a large data set of 640,482 SARS-CoV-2 high quality, full length sequences using a prospective in silico trial design and explored the potential impact of rapid in situ variant testing on the COVID-19 diagnosis and treatment patient pathway. Results: Five SNPs were selected by screening the published literature for a reported association with increased transmission and / or immune evasion. 344881 sequences contained one or more of the five SNPs. This algorithm of SNPs was found to be able to identify the four variants of concern (VOCs) and sequences containing the E484K and L452R escape mutations.Interpretation: The in silico analysis suggest that the key mutations and variants of SARS-CoV-2 may be reliably detected using a focused algorithm of biologically relevant SNPs. This highlights the potential for rapid in situ PCR genotyping to compliment or replace sequencing or to be utilized instead of sequences in settings where sequencing is not feasible, accessible or affordable. Rapid detection of variants with in situ PCR genotyping may facilitate a more effective COVID-19 diagnosis and treatment patient pathway. Funding: The study was funded by Primer Design (UK), with kind contributions from all academic partners.Declaration of Interests: Stephen Kidd, Nick Cortes, Nathan Moore, Kate Templeton, Alex Richter and Alice Goring have no conflicting interests. R.A Trevor, Daryl Borley, Paul Oladimeji, Prachi Teltumbde, Seden Grippon, and Aida Sanchez-Bretano are employees of Novacyt group, which is a medical diagnostics company operating in the COVID-19 variant testing field. R.A Trevor has no additional direct conflicts but is a shareholder in a number of un-related private and public companies that do not operate in the COVID-19 or diagnostics field. Joanne Martin has no direct conflicts of interest. She is a principal investigator of a care home trial using Novacyt rapid testing and National Specialty Advisor for Pathology for NHS England and Improvement. She is a director and shareholder of Biomoti a drug delivery company and has a shareholding in Glyconics, a diagnostics company.

Comparison of SARS-CoV-2 serological assays for use in epidemiological surveillance in Scotland (preprint)

Background: Sero-surveillance of SARS-CoV-2 is crucial to monitoring levels of population exposure and informing public health responses, but may be influenced by variability in performance between available assays. Methods: Five commercial immunoassays and a neutralising activity assay were used to detect antibodies to SARS-CoV-2 in routine primary care and paediatric samples collected during the first wave of the pandemic in NHS Lothian, Scotland as part of ongoing surveillance efforts. For each assay, sensitivity and specificity was calculated relative to consensus results and neutralising activity. Quantitative correlation was performed between serological and neutralising titres. Results: Seroprevalence ranged from 3.4-7.3 % in primary care patients and 3-5.9 % in paediatric patients according to different immunoassays. Neutralising activity was detectable in 2.8 % and 1.3 % respectively. Relative assay performance changed depending on comparison to immunoassay consensus versus neutralising activity and qualititative versus quantitative agreement. Cross-reactivity with endemic seasonal coronaviruses was confirmed by neutralising assay in false positives for one immunoassay. Presence of false positives for another assay was found specifically in paediatric but not adult samples. Conclusions: Five serological assays show variable accuracy when applied to the general population, impacting seroprevalence estimates. Assay performance may also vary in detection of protective neutralising antibody levels. These aspects should be considered in assay selection and interpretation in epidemiological studies.

Epidemic waves of COVID-19 in Scotland: a genomic perspective on the impact of the introduction and relaxation of lockdown on SARS-CoV-2 (preprint)

The second SARS virus, SARS-CoV-2, emerged in December 2019, and within a month was globally distributed. It was first introduced into Scotland in February 2020 associated with returning travellers and visitors. By March it was circulating in communities across the UK, and to control COVID-19 cases, and prevent overwhelming of the National Health Service (NHS), a 'lockdown' was introduced on 23rd March 2020 with a restriction of people's movements. To augment the public health efforts a large-scale genome epidemiology effort (as part of the COVID-19 Genomics UK (COG-UK) consortium) resulted in the sequencing of over 5000 SARS-CoV-2 genomes by 18th August 2020 from Scottish cases, about a quarter of the estimated number of cases at that time. Here we quantify the geographical origins of the first wave introductions into Scotland from abroad and other UK regions, the spread of these SARS-CoV-2 lineages to different regions within Scotland (defined at the level of NHS Health Board) and the effect of lockdown on virus 'success'. We estimate that approximately 300 introductions seeded lineages in Scotland, with around 25% of these lineages composed of more than five viruses, but by June circulating lineages were reduced to low levels, in line with low numbers of recorded positive cases. Lockdown was, thus, associated with a dramatic reduction in infection numbers and the extinguishing of most virus lineages. Unfortunately since the summer cases have been rising in Scotland in a second wave, with >1000 people testing positive on a daily basis, and hospitalisation of COVID-19 cases on the rise again. Examining the available Scottish genome data from the second wave, and comparing it to the first wave, we find that while some UK lineages have persisted through the summer, the majority of lineages responsible for the second wave are new introductions from outside of Scotland and many from outside of the UK. This indicates that, while lockdown in Scotland is directly linked with the first wave case numbers being brought under control, travel-associated imports (mostly from Europe or other parts of the UK) following the easing of lockdown are responsible for seeding the current epidemic population. This demonstrates that the impact of stringent public health measures can be compromised if following this, movements from regions of high to low prevalence are not minimised.

Inactivated rabies virus vectored SARS-CoV-2 vaccine prevents disease in a Syrian hamster model. (preprint)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emergent coronavirus that has caused a worldwide pandemic. Although human disease is often asymptomatic, some develop severe illnesses such as pneumonia, respiratory failure, and death. There is an urgent need for a vaccine to prevent its rapid spread as asymptomatic infections accounting for up to 40% of transmission events. Here we further evaluated an inactivated rabies vectored SARS-CoV-2 S1 vaccine CORAVAX in a Syrian hamster model. CORAVAX adjuvanted with MPLA-AddaVax, a TRL4 agonist, induced high levels of neutralizing antibodies and generated a strong Th1-biased immune response. Vaccinated hamsters were protected from weight loss and viral replication in the lungs and nasal turbinates three days after challenge with SARS-CoV-2. CORAVAX also prevented lung disease, as indicated by the significant reduction in lung pathology. This study highlights CORAVAX as a safe, immunogenic, and efficacious vaccine that warrants further assessment in human trials.