Systemic SARS-CoV-2-specific antibody responses to infection and to COVID-19 and BCG vaccination (preprint)

SARS-CoV-2 infections elicit antibodies against the viral spike (S) and nucleocapsid (N) proteins; COVID-19 vaccines against the S-protein only. The BCG-Corona trial, initiated in March 2020 in SARS-CoV-2-naive Dutch healthcare workers, captured several epidemic peaks and the introduction of COVID-19 vaccines during the one-year follow-up. We assessed determinants of systemic anti-S1 and anti-N immunoglobulin type G (IgG) responses using trial data. Participants were randomized to BCG or placebo vaccination, reported daily symptoms, SARS-CoV-2 test results, and COVID-19 vaccinations, and donated blood for SARS-CoV-2 serology at two time points. In the 970 participants, anti-S1 geometric mean antibody concentrations (GMCs) were much higher than anti-N GMCs. Anti-S1 GMCs significantly increased with increasing number of immune events (SARS-CoV-2 infection or COVID-19 vaccination): 104.7 international units (IU)/ml, 955.0 IU/ml, and 2290.9 IU/ml for one, two, and three immune events, respectively (p<0.001). In adjusted multivariable linear regression models, anti-S1 and anti-N log10 concentrations were significantly associated with infection severity, and anti-S1 log10 concentration with COVID-19 vaccine type/dose. In univariable models, anti-N log10 concentration was also significantly associated with acute infection duration, and severity and duration of individual symptoms. Antibody concentrations were not associated with Long COVID or long-term loss of smell/taste.

Bacillus Calmette-Guerin vaccine to reduce COVID-19 infections and hospitalisations in healthcare workers: a living systematic review and prospective ALL-IN meta-analysis of individual participant data from randomised controlled trials (preprint)

BACKGROUND: The objective is to determine the impact of the Bacillus Calmette-Guerin (BCG) vaccine compared to placebo or no vaccine on COVID-19 infections and hospitalisations in healthcare workers. We are using a living and prospective approach to Individual-Participant-Data (IPD) meta-analysis of ongoing studies based on the Anytime Live and Leading Interim (ALL-IN) meta-analysis statistical methodology. METHODS: Planned and ongoing randomised controlled trials were identified from trial registries and by snowballing (final elicitation: Oct 3 2022). The methodology was specified prospectively -- with no trial results available -- for trial inclusion as well as statistical analysis. Inclusion decisions were made collaboratively based on a risk-of-bias assessment by an external protocol review committee (Cochrane risk-of-bias tool adjusted for use on protocols), expected homogeneity in treatment effect, and agreement with the predetermined event definitions. The co-primary endpoints were incidence of COVID-19 infection and COVID-19-related hospital admission. Accumulating IPD from included trials was analysed sequentially using the exact e-value logrank test (at level alpha = 0.5% for infections and level alpha = 4.5% for hospitalisations) and anytime-valid 95%-confidence intervals (CIs) for the hazard ratio (HR) for a predetermined fixed-effects approach to meta-analysis (no measures of statistical heterogeneity). Infections were included if demonstrated by PCR tests, antigen tests or suggestive lung CTs. Participants were censored at date of first COVID-19-specific vaccination and two-stage analyses were performed in calendar time, with a stratification factor per trial. RESULTS: Six trials were included in the primary analysis with 4 433 participants in total. The e-values showed no evidence of a favourable effect of minimal clinically relevance (HR < 0.8) in comparison to the null (HR = 1) for COVID-19 infections, nor for COVID-19 hospitalisations (HR < 0.7 vs HR = 1). COVID-19 infection was observed in 251 participants receiving BCG and 244 participants not receiving BCG, HR 1.02 (anytime-valid 95%-CI 0.78-1.35). COVID-19 hospitalisations were observed in 13 participants receiving BCG and 7 not receiving BCG, resulting in an uninformative estimate (HR 1.88; anytime-valid 95%-CI 0.26-13.40). DISCUSSION: It is highly unlikely that BCG has a clinically relevant effect on COVID-19 infections in healthcare workers. With only limited observations, no conclusion could be drawn for COVID-19 related hospitalisation. Due to the nature of ALL-IN meta-analysis, emerging data from new trials can be included without violating type-I error rates or interval coverage. We intend to keep this meta-analysis alive and up-to-date, as more trials report. For COVID-19 related hospitalisations, we do not expect enough future observations for a meaningful analysis. For BCG-mediated protection against COVID-19 infections, on the other hand, more observations could lead to a more precise estimate that concludes the meta-analysis for futility, meaning that the current interval excludes the HR of 0.8 predetermined as effect size of minimal clinical relevance. OTHER: No external funding. Preregistered at PROSPERO: CRD42021213069.

BCG vaccination of healthcare workers does not reduce SARS-CoV-2 infections nor infection severity or duration: a randomised placebo-controlled trial (preprint)

Background. Bacillus Calmette-Guerin (BCG) vaccination has been hypothesised to reduce SARS-CoV-2 infection, severity, and/or duration via trained immunity induction. Methods. Healthcare workers (HCWs) in 9 Dutch hospitals were randomised to BCG or placebo vaccination (1:1) in March/April 2020 and followed for one year. They reported daily symptoms, SARS-CoV-2 test results, and healthcare-seeking behaviour via a smartphone application, and donated blood for SARS-CoV-2 serology at two time points. Results. 1,511 HCWs were randomised and 1,309 analysed (665 BCG and 644 placebo). Of the 298 infections detected during the trial, 74 were detected by serology only. The SARS-CoV-2 incidence rates were 0.25 and 0.26 per person-year in the BCG and placebo groups, respectively (incidence rate ratio=0.95; 95% confidence interval 0.76-1.21; p=0.732). Only three participants required hospitalisation for COVID-19. The proportions of participants with asymptomatic, mild, or mild-to-moderate infections, and the mean infection durations, did not differ between randomisation groups. Unadjusted and adjusted logistic regression and Cox proportional hazards models showed no differences between BCG and placebo vaccination for any of these outcomes either. The percentage of participants with seroconversion (7.8% versus 2.8%; p=0.006) and mean anti-S1 antibody concentration (13.1 versus 4.3 IU/ml; p=0.023) were higher in the BCG than placebo group at 3 months but not at 6 or 12 months post-vaccination. Conclusions. BCG vaccination of HCWs did not reduce SARS-CoV-2 infections nor infection duration or severity (on a scale from asymptomatic to moderate). In the first 3 months after vaccination, BCG vaccination may enhance SARS-CoV-2 antibody production during SARS-CoV-2 infection.

Efficacy and Safety of the CVnCoV SARS-CoV-2 mRNA Vaccine Candidate: Results from Herald, a Phase 2b/3, Randomised, Observer-Blinded, Placebo-Controlled Clinical Trial in Ten Countries in Europe and Latin America (preprint)

Background: Additional safe and effective vaccines are needed to control the COVID-19 pandemic.Methods: HERALD is an ongoing phase 2b/3 randomised, observer-blinded, placebo-controlled clinical trial in ten countries in Europe and Latin America. SARS-CoV-2 naïve adults were randomised 1:1 to receive two doses of CVnCoV mRNA vaccine candidate or placebo 28 days apart. Primary efficacy analysis included symptomatic COVID-19 more than 14 days after second dose. Solicited adverse events (AEs) were assessed in phase 2b participants and unsolicited AEs in all participants. The study is registered at ClinicalTrials.gov (NCT04652102).Findings: Between 11 December 2020 and 12 April 2021, 39 680 participants were randomised and 39 529 received CVnCoV (19 783) or placebo (19 746). Overall VE was 48·2% (95% CI: 31·0–61·4; 83/12 851 vs. 145/12 221 in CVnCoV and placebo recipients, respectively). Overall VE against moderate-to-severe COVID-19 was 70·7% (95% CI: 42·5–86·1; 12/12 851 vs. 37/12 211, respectively). In participants aged 18–60 years VE was 52·5% (95% CI: 36·2–64·8; 71/11 532 vs. 136/11 031, respectively). Too few cases occurred in participants aged ≥61 years (CVnCoV: 12, placebo: 9) precluding VE evaluation. Wild type SARS-CoV-2 was detected in 7/204 (3%) sequenced cases, with 14 variants being responsible for the other cases. Solicited adverse events, mostly systemic, were more common in CVnCoV recipients; 542/2002 CVnCoV recipients and 61/1980 placebo recipients reported grade 3 events. Unsolicited serious AEs were reported for 82/19 746 CVnCoV recipients and 66/19 746 placebo recipients; 8 and 2 SAEs, respectively were considered related to vaccination. Fatal SAEs were reported for 8 and 6 CVnCoV and placebo recipients.Interpretation: CVnCoV is efficacious in the prevention of COVID-19 of any severity and has an acceptable safety profile.Trial Registration: Study number: ClinicalTrials.gov Identifier: NCT04652102. Funding: This trial was funded by the German Federal Ministry of Education and Research (grant01KI20703), and CureVac AG.Declaration of Interest: MB declares institutional funding from CureVac during the conduct of this study, from Janssen Vaccines, molecular partners, and Merck outside of the submitted work, and consulting fees from Janssen Vaccines. EJLDB, and MFMR, TO and XSL declare institutional funding from CureVac during the conduct of this study. LE, and LG declare institutional funding from CureVac during the conduct of this study and outside of the submitted work. CFL declares institutional funding from CureVac during the conduct of this study, and outside of the submitted work, and is a member of WHO Covid-19 Vaccine Effectiveness Working Group and WHO Product Development for Vaccines Advisory Committee (PDVAC). CL declares institutional funding from CureVac during the conduct of this study, and is a member of the of German Society of Infection board. ILR declares institutional funding from CureVac during the conduct of this study and from J &J, and OSE Immunotherapeutics outside of the submitted work. PGK declares institutional funding from CureVac during the conduct of this study, and is a member of the scientific advisory board for the HERALD clinical trial. VVRH declares institutional funding from CureVac during the conduct of this study, and speakers fees from Gilead outside of the submitted work. HJ declares consultant fees from CureVac, is the Medical Responsible Person for the HERALD clinical trial, and is co-chair of DSMB for the HERALD clinical trial. AK and PM are employed by CureVac, and hold stock options. OSK declares consultant fees from CureVac during the conduct of this study, and is a member of the DSMB for a CVnCoV phase 1 trial. TV declares consultant fees from CureVac during the conduct of this study, and consultant fees from CureVac, AstraZeneca, Pfizer, Johnson&Johnson, and Moderna outside of the submitted work. LO is employed by CureVac, and holds stock options, and is the holder of a pending patent. The other authors declare no competing interests.Ethical Approval: The trial protocol and amendments have been approved by the appropriate independent ethics committee or institutional review board at each study centre

Human Plasma IgG1 Repertoires are Simple, Unique, and Dynamic (preprint)

The human body produces a vast variety of circulating immunoglobulins (Igs) to recognize and combat pathogens and other non-self molecular components. In human plasma the most abundant class of Igs is the immunoglobulin G subclass I (IgG1) 1. Through somatic recombination and hypermutation, our bodies can theoretically produce several billions of distinct IgG1 variants 2,3. The theoretically available IgG1 repertoire thereby far exceeds the physical number of memory B cells available 4. The theoretical possibilities are highly suggestive of a vastly complex IgG1 plasma repertoire, but here we show that in all studied individuals, this repertoire is dominated by only a few dozens of clones. Our data indicate that each person’s IgG1 repertoire is distinctly unique, representing a personalized barcode. We sequentially measured IgG1 repertoires of critically ill individuals with hospital-acquired sepsis, revealing the occurrence and disappearance of specific IgG1 clones during the evolution of the disease. We demonstrate here that 1) personalized IgG1 profiling by LC-MS is feasible, 2) each person exhibits a unique serological IgG1 repertoire, 3) this repertoire adapts to changes in physiology, and 4) that individual plasma IgG clones can be de novo sequenced by integrative protein-centric and peptide-centric proteomic approaches. We foresee that the presented mass spectrometric approach will accommodate more rapid development of monoclonal antibody treatments, immediately assessing fully human, matured, and optimized molecules. The potential of repertoires from disease survivors can then be used to prevent disease excesses, as was demonstrated for Ebola 5-7, and is the hope for the current COVID-19 pandemic.

Model-based evaluation of school- and non-school-related measures to control the COVID-19 pandemic (preprint)

BackgroundIn autumn 2020, many countries, including the Netherlands, are experiencing a second wave of the COVID-19 pandemic. Health policymakers are struggling with choosing the right mix of measures to keep the COVID-19 case numbers under control, but still allow a minimum of social and economic activity. The priority to keep schools open is high, but the role of school-based contacts in the epidemiology of SARS-CoV-2 is incompletely understood. We used a transmission model to estimate the impact of school contacts on transmission of SARS-CoV-2 and to assess the effects of school-based measures, including school closure, on controlling the pandemic at different time points during the pandemic. Methods and FindingsThe age-structured model was fitted to age-specific seroprevalence and hospital admission data from the Netherlands during spring 2020. Compared to adults older than 60 years, the estimated susceptibility was 23% (95%CrI 20--28%) for children aged 0 to 20 years and 61% (95%CrI 50%--72%) for the age group of 20 to 60 years. The time points considered in the analyses were (i) August 2020 when the effective reproduction number (Re) was estimated to be 1.31 (95%CrI 1.15--2.07), schools just opened after the summer holidays and measures were reinforced with the aim to reduce Re to a value below 1, and (ii) November 2020 when measures had reduced Re to 1.00 (95%CrI 0.94--1.33). In this period schools remained open. Our model predicts that keeping schools closed after the summer holidays, in the absence of other measures, would have reduced Re by 10% (from 1.31 to 1.18 (95%CrI 1.04--1.83)) and thus would not have prevented the second wave in autumn 2020. Reducing non-school-based contacts in August 2020 to the level observed during the first wave of the pandemic would have reduced Re to 0.83 (95%CrI 0.75--1.10). Yet, this reduction was not achieved and the observed Re in November was 1.00. Our model predicts that closing schools in November 2020 could reduce Re from the observed value of 1.00 to 0.84 (95%CrI 0.81--0.90), with unchanged non-school based contacts. Reductions in Re due to closing schools in November 2020 were 8% for 10 to 20 years old children, 5% for 5 to 10 years old children and negligible for 0 to 5 years old children. ConclusionsThe impact of measures reducing school-based contacts, including school closure, depends on the remaining opportunities to reduce non-school-based contacts. If opportunities to reduce Re with non-school-based measures are exhausted or undesired and Re is still close to 1, the additional benefit of school-based measures may be considerable, particularly among the older school children.

Screening for SARS-CoV-2 infection in asymptomatic individuals using the Panbio COVID-19 Antigen Rapid Test (Abbott) compared to RT-qPCR (preprint)

BackgroundAntigen-based point of care tests for identification of SARS-CoV-2 may markedly enhance effectiveness of population-based controlling strategies. Previous studies have demonstrated acceptable sensitivity and high specificity compared to RT-qPCR in symptomatic individuals, but test performance for asymptomatic individuals is unknown. MethodsTest performance of the Panbio COVID-19 Ag Rapid Test (Abbott) was compared to RT-qPCR in a longitudinal cohort study of asymptomatic football players and staff members of professional football clubs. Based on timing of symptoms and prior and subsequent test results, positive RT-qPCR tests were categorized as pre-symptomatic, early or late infection or persistent RNA shedding. Findings2425 tests were performed in 824 individuals, of which 52 (6.3%) were SARS-CoV-2 positive based on RT-qPCR. There were 2406 paired sets from asymptomatic subjects for analysis. Sixteen Panbio tests were inconclusive, for which sensitivity analyses were performed (considering results as either positive or negative or being excluded). Sensitivity of Panbio ranged from 61.76% (95% CI 49.2-73.3) to 69.12% (95% CI: 56.7-79.8) and specificity from 99.53% (95% CI: 99.2-99.8) to 100% (95% CI: 99.8-100). Sensitivity of Panbio to detect subjects with pre-symptomatic/early infection (n= 42) ranged from 81.82% (95% CI: 67.3-91.8) to 90.91% (95% CI: 78.3-97.5) with specificity always above 99%. InterpretationIn asymptomatic subjects the Panbio COVID-19 Ag Rapid Test had sensitivity of 81.82% to 90.91% and specificity above 99% for identifying pre-symptomatic and early SARS-CoV-2 infection. FundingThis study was funded by the executing institutes. The Panbio COVID-19 Ag Rapid Tests were provided by the Ministry of Health, Welfare and Sport (VWS).

Real-life validation of the Panbio COVID-19 Antigen Rapid Test (Abbott) in community-dwelling subjects with symptoms of potential SARS-CoV-2 infection (preprint)

Background: RT-qPCR is the reference test for identification of active SARS-CoV-2 infection, but is associated with diagnostic delay. Antigen detection assays can generate results within 20 minutes and outside of laboratory settings. Yet, their diagnostic test performance in real life settings has not been determined. Methods: The diagnostic value of the Panbio COVID-19 Ag Rapid Test (Abbott), was determined in comparison to RT-qPCR (Seegene Allplex) in community-dwelling mildly symptomatic subjects in a medium (Utrecht, the Netherlands) and high endemic area (Aruba), using two concurrently obtained nasopharyngeal swabs. Findings: 1367 and 208 subjects were enrolled in Utrecht and Aruba, respectively. SARS-CoV-2 prevalence, based on RT-qPCR, was 10.2% (n=139) and 30.3% (n=63) in Utrecht and Aruba respectively. Specificity of the Panbio COVID-19 Ag Rapid Test was 100% (95%CI: 99.7-100%) in both settings. Test sensitivity was 72.6% (95%CI: 64.5-79.9%) in the Netherlands and 81.0% (95% CI: 69.0-89.8%) in Aruba. Probability of false negative results was associated with RT-qPCR Ct-values, but not with duration of symptoms. Restricting RT-qPCR test positivity to Ct-values <32 yielded test sensitivities of 95.2% (95%CI: 89.3-98.5%) in the Netherlands and 98.0% (95%CI: 89.2-99.95%) in Aruba. Interpretation: In community-dwelling subjects with mild respiratory symptoms the Panbio COVID-19 Ag Rapid Test had 100% specificity, and a sensitivity above 95% for nasopharyngeal samples when using Ct values <32 cycles as cut-off for RT-qPCR test positivity. Considering short turnaround times, user friendliness, low costs and opportunities for decentralized testing, this test can improve our efforts to control transmission of SARS-CoV-2. Funding: UMCU and LABHOH, Aruba