KCL TEST: an open-source inspired asymptomatic SARS-CoV-2 surveillance programme in an academic institution (preprint)

Testing was paramount in the management of the COVID-19 pandemic. Rapid deployment of new laboratories became widespread worldwide. Our university established KCL TEST: a SARS-CoV-2 asymptomatic testing programme that enabled sensitive and accessible PCR testing of SARS-CoV-2 RNA in saliva at 20 to 50% the price of commercial kits. We performed 158,277 PCRs in saliva for staff, students and their household contacts of Kings College London, free of charge and with an average turnaround time of 8 hours. Our pipeline is mainly made of open-source automation and non-commercial reagents and has been recently recommended for ISO15189 accreditation. Here we provide our blueprint and results to enable the rapid launch of diagnostic laboratories where and when needed. Our data span over 18 months and parallels that of the UK Office for National Statistics, with a lower positive rate and virtually no delta wave. Our observations strongly support regular asymptomatic community testing to decrease outbreaks and provide safe working spaces. KCL TEST demonstrates that universities can provide agile, resilient and accurate testing that reflects the infection rate and trend of the general population. We call for the integration of academic institutions in pandemic preparedness, with capabilities to rapidly deploy highly skilled staff, as well as develop, test and accommodate efficient low-cost pipelines.

The effect of Omicron breakthrough infection and extended BNT162b2 booster dosing on neutralization breadth against SARS-CoV-2 variants of concern (preprint)

COVID-19 vaccines are playing a vital role in controlling the COVID-19 pandemic. As SARS-CoV-2 variants encoding mutations in the surface glycoprotein, Spike, continue to emerge, there is increased need to identify immunogens and vaccination regimens that provide the broadest and most durable immune responses. We compared the magnitude and breadth of the neutralizing antibody response, as well as levels of Spike-reactive memory B cells, in individuals receiving a second dose of BNT126b2 at a short (3-4 week) or extended interval (8-12 weeks) and following a third vaccination approximately 6-8 months later. We show that whilst an extended interval between the first two vaccinations can greatly increase the breadth of the immune response and generate a higher proportion of Spike reactive memory B cells, a third vaccination leads to similar levels between the two groups. Furthermore, we show that the third vaccine dose enhances neutralization activity against omicron lineage members BA.1, BA.2 and BA.4/BA.5 and this is further increased following breakthrough infection during the UK omicron wave. These findings are relevant for vaccination strategies in populations where COVID-19 vaccine coverage remains low.

Antibody levels following vaccination against SARS-CoV-2: associations with post-vaccination infection and risk factors (preprint)

SARS-CoV-2 antibody levels can be used to assess humoral immune responses following SARS-CoV-2 infection or vaccination, and may predict risk of future infection. From cross-sectional antibody testing of 9,361 individuals from TwinsUK and ALSPAC UK population-based longitudinal studies (jointly in April-May 2021, and TwinsUK only in November 2021-January 2022), we tested associations between antibody levels following vaccination and: (1) SARS-CoV-2 infection following vaccination(s); (2) health, socio-demographic, SARS-CoV-2 infection and SARS-CoV-2 vaccination variables. Within TwinsUK, single-vaccinated individuals with the lowest 20% of anti-Spike antibody levels at initial testing had 3-fold greater odds of SARS-CoV-2 infection over the next six to nine months, compared to the top 20%. In TwinsUK and ALSPAC, individuals identified as at increased risk of COVID-19 complication through the UK "Shielded Patient List" had consistently greater odds (2 to 4-fold) of having antibody levels in the lowest 10%. Third vaccination increased absolute antibody levels for almost all individuals, and reduced relative disparities compared with earlier vaccinations. These findings quantify the association between antibody level and risk of subsequent infection, and support a policy of triple vaccination for the generation of protective antibodies.

Concordance of B and T cell responses to SARS-CoV-2 infection, irrespective of symptoms suggestive of COVID-19. (preprint)

ObjectivesTo assess T cell responses in individuals with and without a positive antibody response to SARS-CoV-2, in symptomatic and asymptomatic individuals during the COVID-19 pandemic. MethodsParticipants were drawn from the TwinsUK cohort, selected according to a) presence or absence of COVID-associated symptoms (S+, S-), logged prospectively through the COVID Symptom Study app, and b) Anti-IgG Spike and anti-IgG Nucleocapsid antibodies measured by ELISA (Ab+, Ab-), during the first wave of the UK pandemic. T cell helper and regulatory responses after stimulation with SARS-CoV-2 peptides were assessed. Results32 participants were included in final analysis. 14 of 15 with IgG Spike antibodies had a T cell response to SARS-CoV-2-specific peptides; none of 17 participants without IgG Spike antibodies had a T cell response (Chi-squared 28.2, p<0.001). Quantitative T cell responses correlated strongly with fold-change in IgG Spike antibody titre (rho=0.79, p<0.0001) but not to symptom score (rho=0.17, p=0.35). ConclusionsHumoral and cellular immune responses to SARS-CoV-2 are highly correlated, with no evidence that cellular immunity differs from antibody status four months after acute illness.

Humoral responses following SARS-CoV-2 breakthrough infection in COVID-19 vaccinated individuals (preprint)

Numerous studies have shown that a prior SARS-CoV-2 infection can greatly enhance the antibody response to COVID-19 vaccination, with this so called "hybrid immunity" leading to greater neutralization breadth against SARS-CoV-2 variants of concern. However, little is known about how breakthrough infection (BTI) in COVID-19 vaccinated individuals will impact the magnitude and breadth of the neutralizing antibody response. Here, we compared neutralizing antibody responses between unvaccinated and COVID-19 vaccinated individuals (including both AZD1222 and BNT162b2 vaccinees) who have been infected with the delta (B.1.617.2) variant. Rapid production of Spike-reactive IgG was observed in the vaccinated group providing evidence of effective vaccine priming. Overall, potent cross-neutralizing activity against current SARS-CoV-2 variants of concern was observed in the BTI group compared to the infection group. This study provides important insights into population immunity where transmission levels remain high.

Antibody longevity and cross-neutralizing activity following SARS-CoV-2 wave 1 and B.1.1.7 infections (preprint)

As SARS-CoV-2 variants continue to emerge globally, a major challenge for COVID-19 vaccination is the generation of a durable antibody response with cross-neutralizing activity against both current and newly emerging viral variants. Cross-neutralizing activity against major variants of concern (B.1.1.7, P.1 and B.1.351) has been observed following vaccination, albeit at a reduced potency, but whether vaccines based on the Spike glycoprotein of these viral variants will produce a superior cross-neutralizing antibody response has not been fully investigated. Here, we used sera from individuals infected in wave 1 in the UK to study the long-term cross-neutralization up to 10 months post onset of symptoms (POS), as well as sera from individuals infected with the B.1.1.7 variant to compare cross-neutralizing activity profiles. We show that neutralizing antibodies with cross-neutralizing activity can be detected from wave 1 up to 10 months POS. Although neutralization of B.1.1.7 and B.1.351 is lower, the difference in neutralization potency decreases at later timepoints suggesting continued antibody maturation and improved tolerance to Spike mutations. Interestingly, we found that B.1.1.7 infection also generates a cross-neutralizing antibody response, which, although still less potent against B.1.351, can neutralize parental wave 1 virus to a similar degree as B.1.1.7. These findings have implications for the optimization of vaccines that protect against newly emerging viral variants.

Single dose of BNT162b2 mRNA vaccine against SARS-CoV2 induces neutralizing antibody and polyfunctional T-cell responses in patients with CML (preprint)

Patients receiving targeted cancer treatments such as tyrosine kinase inhibitors (TKIs) have been classified in the clinically extremely vulnerable group to develop severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including patients with Chronic Myeloid Leukaemia (CML) taking TKIs. In addition, concerns that immunocompromised individuals with solid and haematological malignancies may not mount an adequate immune response to a single dose of SARS-CoV-2 BNT162b2 (Pfizer- BioNTech) vaccine have been raised. We evaluated humoral and cellular immune responses after a first injection of BNT162b2 vaccine in 16 CML patients. Seroconversion and cellular immune response prior and after vaccination were assessed. By day 21 post-vaccination, anti-Spike IgG were detected in 14/16 (87.5%) of CML patients and all developed a neutralizing antibody response (ID50>50), including medium (ID50 of 200-500) or high (501-2000) neutralising antibodies titres in 9/16 (56.25%) patients. T cell response was seen in 14/15 (93.3%) evaluable patients, with polyfunctional responses seen in 12/15 (80%) patients (polyfunctional CD4+ response 9/15, polyfunctional CD8+ T cell response 9/15). These data demonstrate the immunogenicity of a single dose of SARS-CoV-2 BNT162b2 vaccine in most CML patients with both neutralizing antibodies and polyfunctional T-cell responses seen, in contrast to patients with solid tumour or lymphoid haematological malignancies.

Comparative performance of SARS-CoV-2 lateral flow antigen tests demonstrates their utility for high sensitivity detection of infectious virus in clinical specimens (preprint)

Background: Rapid antigen lateral flow devices (LFDs) are set to become a cornerstone of SARS-CoV-2 mass community testing. However, their reduced sensitivity compared to PCR has raised questions of how well they identify infectious cases. Understanding their capabilities and limitations is therefore essential for successful implementation. To address this, we evaluated six commercial LFDs on the same collection of clinical samples and assessed their correlation with infectious virus culture and cycle threshold (Ct) values. Methods: A head-to-head comparison of specificities and sensitivities was performed on six commercial rapid antigen tests using combined nasal/oropharyngeal swabs, and their limits of detection determined using viral plaque forming units (PFU). Three of the LFDs were selected for a further study, correlating antigen test result with RT-PCR Ct values and positive viral culture in Vero-E6 cells. This included sequential swabs and matched serum samples obtained from four infected individuals with varying disease severities. Detection of antibodies was performed using an IgG/IgM Rapid Test Cassette, and neutralising antibodies by infectious virus assay. Finally, the sensitivities of selected rapid antigen LFTs were assessed in swabs with confirmed B.1.1.7 variant, currently the dominant genotype in the UK. Findings: Most of the rapid antigen LFDs showed a high specificity (>98%), and accurately detected 50 PFU/test (equivalent N1 Ct of 23.7 or RNA copy number of 3x106/ml). Sensitivities of the LFDs performed on clinical samples ranged from 65 to 89%. These sensitivities increased in most tests to over 90% for samples with Cts lower than 25. Positive virus culture was achieved for 57 out of 141 samples, with 80% of the positive cultures from swabs with Cts lower than 23. Importantly, sensitivity of the LFDs increased to over 95% when compared with the detection of infectious virus alone, irrespective of Ct. Longitudinal studies of PCR-positive samples showed that most of the tests identified all infectious samples as positive, but differences in test sensitivities can lead to missed cases in the absence of repeated testing. Finally, test performance was not impacted when re-assessed against swabs positive for the dominant UK variant B.1.1.7. Interpretation: In this comprehensive comparison of antigen LFD and virus infectivity, we demonstrate a clear relationship between Ct values, quantitative culture of infectious virus and antigen LFD positivity in clinical samples. Our data support regular testing of target groups using LFDs to supplement the current PCR testing capacity, to rapidly identify infected individuals in situations where they would otherwise go undetected.

SARS-CoV-2 recruits a haem metabolite to evade antibody immunity (preprint)

The coronaviral spike is the dominant viral antigen and the target of neutralizing antibodies. We show that SARS-CoV-2 spike binds biliverdin and bilirubin, the tetrapyrrole products of haem metabolism, with nanomolar affinity. Using cryo-electron microscopy and X-ray crystallography we mapped the tetrapyrrole interaction pocket to a deep cleft on the spike N-terminal domain (NTD). At physiological concentrations, biliverdin significantly dampened the reactivity of SARS-CoV-2 spike with immune sera and inhibited a subset of neutralizing antibodies. Access to the tetrapyrrole-sensitive epitope is gated by a flexible loop on the distal face of the NTD. Accompanied by profound conformational changes in the NTD, antibody binding requires relocation of the gating loop, which folds into the cleft vacated by the metabolite. Our results indicate that the virus co-opts the haem metabolite for the evasion of humoral immunity via allosteric shielding of a sensitive epitope and demonstrate the remarkable structural plasticity of the NTD.

Indicators of COVID-19 status in a cohort study of university staff and post-graduate research students, including results from home antibody testing (preprint)

BackgroundCohort studies of people with a history of COVID-19 infection and controls will be essential to understand the epidemiology of long-term effects. However, clinical diagnosis requires resources that are frequently restricted to the severely ill. Cohort studies may have to rely on surrogate indicators of COVID-19 illness. We describe the prevalence and overlap of five potential indicators: self-reported suspicion, self-reported core symptoms, symptom algorithm, self-reported routine test results, and home antibody testing. MethodsAn occupational cohort of staff and postgraduate students at a large London university who participated in surveys and antibody testing. Self-report items cover March to June 2020 and antibody test results from lateral flow IgG/IgM antibody test cassettes sent to participants in June 2020. ResultsValid antibody test results were returned for 1882 participants. Of the COVID-19 indicators, the highest prevalence was core symptoms (770 participants positive, 41%), followed by participant suspicion of infection (n=509, 27%), a symptom algorithm (n=297, 16%), study antibody positive test (n=124, 6.6%) and self-report of a positive external test (n=39, 2.1%). Study antibody positive result was rare in people who had no suspicion they had experienced COVID-19 (n=4, 0.7%) or did not experience core symptoms (n=10, 1.6%). When study antibody test results were compared with earlier external antibody results in those who had reported them, the study antibody results agreed in 88% cases (kappa= 0.636), with a lower proportion testing positive on this occasion (proportion with antibodies detected 15% in study test vs 24% in external testing). DiscussionOur results demonstrate that there is some agreement between different COVID indicators, but that they a more complete story when used together. Antibody testing may provide greater certainty and be one of the only ways to detect asymptomatic cases, but is likely to under-ascertain due to weak antibody responses to mild infection, which wane over time. Cohort studies will need to review how they deal with different and sometimes conflicting indicators of COVID-19 illness in order to study the long-term outcomes of COVID-19 infection and related impacts. What is already known on this subject?Research into the effects of COVID-19 in the community is needed to respond to the pandemic. Objective testing has not been widely available and accuracy may not be high when carried out in retrospect. Many cohort studies are considering how best to measure COVID-19 infection status. What this study adds?Antibody testing is feasible, but it is possible that sensitivity may be poor. Each indicator included added different aspects to the ascertainment of COVID-19 exposure. Using combinations of self-reported and objectively measured variables, it may be possible to tailor COVID-19 indicators to the situation.

Combined epidemiological and genomic analysis of nosocomial SARS-CoV-2 transmission identifies community social distancing as the dominant intervention reducing outbreaks (preprint)

Many healthcare facilities report SARS-CoV-2 outbreaks but transmission analysis is complicated by the high prevalence of infection and limited viral genetic diversity. The contribution of different vectors to nosocomial infection or the effectiveness of interventions is therefore currently unclear. Detailed epidemiological and viral nanopore sequence data were analysed from 574 consecutive patients with a PCR positive SARS-CoV-2 test between March 13th and March 31st, when the pandemic first impacted on a large, multisite healthcare institution in London. During this time the first major preventative interventions were introduced, including progressive community social distancing (CSD) policies leading to mandatory national lockdown, exclusion of hospital visitors, and introduction of universal surgical facemask-use by healthcare-workers (HCW). Incidence of nosocomial cases, community SARS-CoV-2 cases and infection in a cohort of 228 HCWs followed the same dynamic course, decreasing shortly after introduction of CSD measures and prior to the main hospital-based interventions. We investigated clusters involving nosocomial cases based on overlapping ward-stays during the 14-day incubation period and SARS-CoV-2 genome sequence similarity. Our method placed 63 (79%) of 80 sequenced probable and definite nosocomial cases into 14 clusters containing a median of 4 patients (min 2, max 19) No genetic support was found for the majority of epidemiological clusters (31/44, 70%) and genomics revealed multiple contemporaneous outbreaks within single epidemiological clusters. We included a measure of hospital enrichment compared to community cases to increase confidence in our clusters, which were 1-14 fold enriched. Applying genomics, we could provide a robust estimate of the incubation period for nosocomial transmission, with a median lower bound and upper bound of 6 and 9 days respectively. Six (43%) clusters spanned multiple wards, with evidence of cryptic transmission, and community-onset cases could not be identified in more than half the clusters, particularly on the elective hospital site, implicating HCW as vectors of transmission. Taken together these findings suggest that CSD had the dominant impact on reducing nosocomial transmission by reducing HCW infection.

Immunophenotyping of Circulating Leukocytes Reveal Non-specific Activation of Innate and Adaptive Immune Systems in Multi-System Inflammatory Syndrome of Childhood Temporally Associated with SARS-Cov-2 Infection: Descriptive Cohort Study (preprint)

We describe the innate and adaptive immune system trajectory in Multi-system inflammatory syndrome of childhood (MIS-C), at acute(within 72 hours of hospitalization), resolution (at clinical improvement) and convalescent phase. In our cohort, in the acute phase, 68% of the children were SARS-CoV-2 seropositive, with hypercytokinenemia (high interleukin(IL)-1beta,IL-6,IL-8,IL-10,IL-17, interferon gamma), procoagulant state, myocardial dysfunction, activated neutrophils and monocytes; differential T and B cell subset lymphopenia; activated chemokine receptor type-7 positive and gamma-delta T cell subsets; antigen presenting cells had reduced HLA-DR expression; and B-cell class-switch responses occurred with illness resolution. MIS-C is an immunopathogenic illness associated with SARS-CoV-2 infections in children.

Longitudinal evaluation and decline of antibody responses in SARS-CoV-2 infection (preprint)

Antibody (Ab) responses to SARS-CoV-2 can be detected in most infected individuals 10-15 days following the onset of COVID-19 symptoms. However, due to the recent emergence of this virus in the human population it is not yet known how long these Ab responses will be maintained or whether they will provide protection from re-infection. Using sequential serum samples collected up to 94 days post onset of symptoms (POS) from 65 RT-qPCR confirmed SARS-CoV-2-infected individuals, we show seroconversion in >95% of cases and neutralizing antibody (nAb) responses when sampled beyond 8 days POS. We demonstrate that the magnitude of the nAb response is dependent upon the disease severity, but this does not affect the kinetics of the nAb response. Declining nAb titres were observed during the follow up period. Whilst some individuals with high peak ID50 (>10,000) maintained titres >1,000 at >60 days POS, some with lower peak ID50 had titres approaching baseline within the follow up period. A similar decline in nAb titres was also observed in a cohort of seropositive healthcare workers from Guys and St Thomas Hospitals. We suggest that this transient nAb response is a feature shared by both a SARS-CoV-2 infection that causes low disease severity and the circulating seasonal coronaviruses that are associated with common colds. This study has important implications when considering widespread serological testing, Ab protection against re-infection with SARS-CoV-2 and the durability of vaccine protection.

Clinical utility of targeted SARS-CoV-2 serology testing to aid the diagnosis and management of suspected missed, late or post-COVID-19 infection syndromes: results from a pilot service (preprint)

Objectives: Determine indications and clinical utility of SARS-CoV-2 serology testing in adults and children. Design: Prospective evaluation of initial three weeks of a daily Monday to Friday pilot SARS-CoV-2 serology service for patients. Setting: Early post 'first-wave' SARS-CoV-2 transmission period at single centre London teaching hospital that provides care to the local community, as well as regional and national referral pathways for specialist services. Participants: 110 (72 adults, 38 children, age range 0-83 years, 52.7% female (n=58)). Interventions: Patient serum from vetted referrals tested on CE marked and internally validated lateral flow immunoassay (LFIA) (SureScreen Diagnostics) detecting antibodies to SARS-CoV-2 spike proteins, with result and clinical interpretation provided to the direct care team. Main outcome measures: Performance characteristics, source and nature of referrals, feasibility and clinical utility of the service, particularly the benefit for clinical decision-making. Results: The LFIA was deemed suitable for clinical advice and decision making following evaluation with 310 serum samples from SARS-CoV-2 PCR positive patients and 300 pre-pandemic samples, giving a sensitivity and specificity of 96.1% and 99.3% respectively. For the pilot, 115 referrals were received leading to 113 tests performed on 108 participants (sample not available for two participants); paediatrics (n=35), medicine (n=69), surgery (n=2) and general practice (n=2). 43.4% participants (n=49) had detectable antibodies to SARS-CoV-2. There were three main indications for serology; new acute presentations potentially triggered by recent COVID-19 infection e.g. PIMS-TS (n=26) and pulmonary embolism (n=5), potential missed diagnoses in context of a recent compatible illness (n=40), and making infection control and immunosuppression treatment decisions in persistently SARS-CoV-2 RNA PCR positive individuals (n=6). Conclusions: This study shows acceptable performance characteristics, feasibility and clinical utility of a SARS-CoV-2 serology service using a rapid, inexpensive and portable assay for adults and children presenting with a range of clinical indications. Results correlated closely with a confirmatory in-house ELISA. The study showed the benefit of introducing a serology service where there is a reasonable pre-test probability, and the result can be linked with clinical advice or intervention. Experience thus far is that the volume of requests from hospital referral routes are manageable within existing clinical and laboratory services; however, the demand from community referrals has not yet been assessed. Given recent evidence for a rapid decline in antibodies, particularly following mild infection, there is likely a limited window of opportunity to realise the benefit of serology testing for individuals infected during the 'first-wave' before they potentially fall below a measurable threshold. Rapidly expanding availability of serology services for NHS patients will also help understand the long-term implications of serostatus and prior infection in different patient groups, particularly before emergence of any 'second-wave' outbreak or introduction of a vaccination programme.

Comparative assessment of multiple COVID-19 serological technologies supports continued evaluation of point-of-care lateral flow assays in hospital and community healthcare settings (preprint)

There is a clear requirement for an accurate SARS-CoV-2 antibody test, both as a complement to existing diagnostic capabilities and for determining community seroprevalence. We therefore evaluated the performance of a variety of antibody testing technologies and their potential as diagnostic tools. A highly specific in-house ELISA was developed for the detection of anti-spike (S), -receptor binding domain (RBD) and -nucleocapsid (N) antibodies and used for the cross-comparison of ten commercial serological assays - a chemiluminescence-based platform, two ELISAs and seven colloidal gold lateral flow immunoassays (LFIAs) - on an identical panel of 110 SARS-CoV-2-positive samples and 50 pre-pandemic negatives. There was a wide variation in the performance of the different platforms, with specificity ranging from 82% to 100%, and overall sensitivity from 60.9% to 87.3%. However, the head-to-head comparison of multiple sero-diagnostic assays on identical sample sets revealed that performance is highly dependent on the time of sampling, with sensitivities of over 95% seen in several tests when assessing samples from more than 20 days post onset of symptoms. Furthermore, these analyses identified clear outlying samples that were negative in all tests, but were later shown to be from individuals with mildest disease presentation. Rigorous comparison of antibody testing platforms will inform the deployment of point-of-care technologies in healthcare settings and their use in the monitoring of SARS-CoV-2 infections.

Resilient SARS-CoV-2 diagnostics workflows including viral heat inactivation (preprint)

There is a worldwide shortage of reagents to perform detection of SARS-2. Many clinical diagnostic laboratories rely on commercial platforms that provide integrated end-to-end solutions. While this provides established robust pipelines, there is a clear bottleneck in the supply of reagents given the current situation of extraordinary high demand. Some laboratories resort to implementing kit-free handling procedures, but many other small laboratories will not have the capacity to develop those and/or will perform manual handling of their samples. In order to provide multiple workflows for SARS-CoV-2 nucleic acid detection we compared several commercially available RNA extraction methods: QIAamp Viral RNA Mini Kit (QIAgen), the recently developed RNAdvance Blood (Beckman) and Mag-Bind Viral DNA/RNA 96 Kit (Omega Bio-tek). We also compared different 1-step RT-qPCR Master Mix brands: TaqMan Fast Virus 1-Step Master Mix (ThermoFisher Scientific), qPCRBIO Probe 1-Step Go Lo-ROX (PCR Biosystems) and Luna(R) Universal Probe One-Step RT-qPCR Kit (NEB). We used the Centre for Disease Control (CDC) recommended primers that detect two regions of the viral N gene as well as those that detect the RdRP gene region as per Public Health England (PHE) guidelines (Charite/WHO/PHE). Our data show that the RNA extraction methods provide similar results. Amongst the qPCR reagents tested, TaqMan Fast Virus 1-Step Master Mix and Luna(R) Universal Probe One-Step RT-qPCR Kit proved most sensitive. The N1 and N2 primer-probes provide a more reliable detection than the RdRP-SARSr primer-probe set, particularly in samples with low viral titres. Importantly, we have implemented a protocol using heat inactivation and demonstrate that it has minimal impact on the sensitivity of the qPCR in clinical samples - potentially making SARS-CoV-2 testing portable to settings that do not have CL-3 facilities.