Rift Valley Fever Virus: An Overview of the Current Status of Diagnostics.

Rift Valley fever is a vector-borne zoonotic disease caused by the Rift Valley fever virus (Phlebovirus genus) listed among the eight pathogens included in the Bluepoint list by the WHO. The transmission is mainly vehicled by Aedes and Culex mosquito species. Symptoms of the disease are varied and non-specific, making clinical diagnosis often challenging, especially in the early stages. Due to the difficulty in distinguishing Rift Valley fever from other viral hemorrhagic fevers, as well as many other diseases that cause fever, an early diagnosis of the infection is important to limit its spread and to provide appropriate care to patients. To date, there is no validated point-of-care diagnostic tool. The virus can only be detected in the blood for a brief period, suggesting that molecular methods alone are not sufficient for case determination. For this, it is preferable to combine both molecular and serological tests. The wide distribution of competent vectors in non-endemic areas, together with global climate change, elicit the spread of RVFV to continents other than Africa, making surveillance activities vital to prevent or to limit the impact of human outbreaks and for a rapid identification of positive cases, making diagnosis a key factor for this achievement.

Effect of chemical and physical agents on monkeypox virus infectivity and downstream research applications.

The 2022 global spread of Monkeypox Virus (MPXV) underlined the need to investigate safe-handling procedures of clinical and research samples. Here we evaluated the efficiency in reducing MPXV infectious titer of Triton X-100 (0.1 and 0.2%), UV-C irradiation (15 or 30 min), and heat (56 °C 30 min or 70 °C 5 min). The treatment of MPXV at 70 °C resulted in the strongest decrease of MPXV infectious titer (5.4 Log TCID50/mL), 56 °C and UV-C had a lighter impact (3.9 and 4.3Log), Triton X-100 was less efficient (1.8-2.5Log). Notably, SARS-CoV-2 was much more susceptible to Triton X-100 (4.0 Log decrease). UV-C had the highest impact on MPXV DNA detection by PCR (2.2-4.3 Ct value increase); protein detection by ELISA was dramatically impaired by heating. Overall, UV-C and heating were more effective in lowering MPXV infectious titer but their impact on nucleic acids or protein detection assays must be considered.

Immunogenicity and reactogenicity of modified vaccinia Ankara pre-exposure vaccination against mpox according to previous smallpox vaccine exposure and HIV infection: prospective cohort study.

Background: Pre-exposure vaccination with MVA-BN has been widely used against mpox to contain the 2022 outbreak. Many countries have defined prioritized strategies, administering a single dose to those historically vaccinated for smallpox, to achieve quickly adequate coverage in front of low supplies. Using epidemiological models, real-life effectiveness was estimated at approximately 36%-86%, but no clinical trials were performed. Few data on MVA-BN immunogenicity are currently available, and there are no established correlates of protection. Immunological response in PLWH in the context of the 2022 outbreak was also poorly described. Methods: Blood samples were collected from participants eligible for pre-exposure MVA-BN vaccination before (T1) receiving a full course of vaccine (single-dose for vaccine-experienced or smallpox-primed and two-dose for smallpox vaccine-naïve or smallpox non-primed) and one month after the last dose (T2 and T3, respectively). MPXV-specific IgGs were measured by in-house immunofluorescence assay, using 1:20 as screening dilution, MPXV-specific nAbs by 50% plaque reduction neutralization test (PRNT50, starting dilution 1:10), and IFN-γ-producing specific T cells to MVA-BN vaccine, by ELISpot assay. Paired or unpaired t-test and Wilcoxon or Mann-Whitney test were used to analyse IgG and nAbs, and T-cell response, as appropriate. The probability of IgG and nAb response in vaccine-experienced vs. vaccine-naïve was estimated in participants not reactive at T1. The McNemar test was used to evaluate vaccination's effect on humoral response both overall and by smallpox vaccination history. In participants who were not reactive at T1, the proportion of becoming responders one month after full-cycle completion by exposure groups was compared by logistic regression and then analysed by HIV status strata (interaction test). The response was also examined in continuous, and the Average Treatment Effect (ATE) of the difference from baseline to schedule completion according to previous smallpox vaccination was estimated after weighting for HIV using a linear regression model. Self-reports of adverse effects following immunization (AEFIs) were prospectively collected after the first MVA-BN dose (T1). Systemic (S-AEFIs: fatigue, myalgia, headache, GI effects, chills) and local (L-AEFIs: redness, swelling, pain) AEFIs were graded as absent (grade 0), mild (1), moderate (2), or severe (3). The maximum level of severity for S-AEFIs and L-AEFIs ever experienced over the 30 days post-dose by vaccination exposure groups were analysed using a univariable multinomial logistic regression model and after adjusting for HIV status; for each of the symptoms, we also compared the mean duration by exposure group using an unpaired t-test. Findings: Among the 164 participants included, 90 (54.8%) were smallpox vaccine-experienced. Median age was 49 years (IQR 41-55). Among the 76 (46%) PLWH, 76% had a CD4 count >500 cells/µL. There was evidence that both the IgG and nAbs titers increased after administration of the MVA-BN vaccine. However, there was no evidence for a difference in the potential mean change in humoral response from baseline to the completion of a full cycle when comparing primed vs. non-primed participants. Similarly, there was no evidence for a difference in the seroconversion rate after full cycle vaccination in the subset of participants not reactive for nAbs at T1 (p = 1.00 by Fisher's exact test). In this same analysis and for the nAbs outcome, there was some evidence of negative effect modification by HIV (interaction p-value = 0.17) as primed people living with HIV (PLWH) showed a lower probability of seroconversion vs. non-primed, and the opposite was seen in PLWoH. When evaluating the response in continuous, we observed an increase in T-cell response after MVA-BN vaccination in both primed and non-primed. There was evidence for a larger increase when using the 2-dose vs. one-dose strategy with a mean difference of -2.01 log2 (p ≤ 0.0001), after controlling for HIV. No evidence for a difference in the risk of developing any AEFIs of any grade were observed by exposure group, except for the lower risk of grade 2 (moderate) fatigue, induration and local pain which was lower in primed vs. non-primed [OR 0.26 (0.08-0.92), p = 0.037; OR 0.30 (0.10-0.88), p = 0.029 and OR 0.19 (0.05-0.73), p = 0.015, respectively]. No evidence for a difference in symptom duration was also detected between the groups. Interpretation: The evaluation of the humoral and cellular response one month after the completion of the vaccination cycle suggested that MVA-BN is immunogenic and that the administration of a two-dose schedule is preferable regardless of the previous smallpox vaccination history, especially in PLWH, to maximize nAbs response. MVA-BN was safe as well tolerated, with grade 2 reactogenicity higher after the first administration in vaccine-naïve than in vaccine-experienced individuals, but with no evidence for a difference in the duration of these adverse effects. Further studies are needed to evaluate the long-term duration of immunity and to establish specific correlates of protection. Funding: The study was supported by the National Institute for Infectious Disease Lazzaro Spallanzani IRCCS "Advanced grant 5 × 1000, 2021" and by the Italian Ministry of Health "Ricerca Corrente Linea 2".

Autochthonous Dengue Fever in 2 Patients, Rome, Italy.

Since August 2023, outbreaks of dengue virus (DENV) infection have occurred in Italy. We report 2 autochthonous case-patients and their extended follow-up. Despite persistent DENV detected in blood by PCR, results for antigenomic DENV RNA were negative after day 5, suggesting that a 5-day isolation period is adequate to avoid secondary cases.

Long Term Assessment of Anti-SARS-CoV-2 Immunogenicity after mRNA Vaccine in Persons Living with HIV.

(1) Background: Waning of neutralizing and cell-mediated immune response after the primary vaccine cycle (PVC) and the first booster dose (BD) is of concern, especially for PLWH with a CD4 count ≤200 cells/mm3. (2) Methods: Neutralizing antibodies (nAbs) titers by microneutralization assay against WD614G/Omicron BA.1 and IFNγ production by ELISA assay were measured in samples of PLWH at four time points [2 and 4 months post-PVC (T1 and T2), 2 weeks and 5 months after the BD (T3 and T4)]. Participants were stratified by CD4 count after PVC (LCD4, ≤200/mm3; ICD4, 201-500/mm3, and HCD4, >500/mm3). Mixed models were used to compare mean responses over T1-T4 across CD4 groups. (3) Results: 314 PLWH on ART (LCD4 = 56; ICD4 = 120; HCD4 = 138) were enrolled. At T2, levels of nAbs were significantly lower in LCD4 vs. ICD4/HCD4 (p = 0.04). The BD was crucial for increasing nAbs titers above 1:40 at T3 and up to T4 for WD614G. A positive T cell response after PVC was observed in all groups, regardless of CD4 (p = 0.31). (4) Conclusions: Waning of nAbs after PVC was more important in LCD4 group. The BD managed to re-establish higher levels of nAbs against WD614G, which were retained for 5 months, but for shorter time for Omicron BA.1. The T cellular response in the LCD4 group was lower than that seen in participants with higher CD4 count, but, importantly, it remained above detectable levels over the entire study period.

Nipah Virus: An Overview of the Current Status of Diagnostics and Their Role in Preparedness in Endemic Countries.

Nipah virus (NiV) is a paramyxovirus responsible for a high mortality rate zoonosis. As a result, it has been included in the list of Blueprint priority pathogens. Bats are the main reservoirs of the virus, and different clinical courses have been described in humans. The Bangladesh strain (NiV-B) is often associated with severe respiratory disease, whereas the Malaysian strain (NiV-M) is often associated with severe encephalitis. An early diagnosis of NiV infection is crucial to limit the outbreak and to provide appropriate care to the patient. Due to high specificity and sensitivity, qRT-PCR is currently considered to be the optimum method in acute NiV infection assessment. Nasal swabs, cerebrospinal fluid, urine, and blood are used for RT-PCR testing. N gene represents the main target used in molecular assays. Different sensitivities have been observed depending on the platform used: real-time PCR showed a sensitivity of about 103 equivalent copies/reaction, SYBRGREEN technology's sensitivity was about 20 equivalent copies/reaction, and in multiple pathogen card arrays, the lowest limit of detection (LOD) was estimated to be 54 equivalent copies/reaction. An international standard for NiV is yet to be established, making it difficult to compare the sensitivity of the different methods. Serological assays are for the most part used in seroprevalence studies owing to their lower sensitivity in acute infection. Due to the high epidemic and pandemic potential of this virus, the diagnosis of NiV should be included in a more global One Health approach to improve surveillance and preparedness for the benefit of public health. Some steps need to be conducted in the diagnostic field in order to become more efficient in epidemic management, such as development of point-of-care (PoC) assays for the rapid diagnosis of NiV.

Evaluation of Cross-Immunity to the Mpox Virus Due to Historic Smallpox Vaccination.

When the Mpox virus (MPXV) began spreading globally in 2022, it became critical to evaluate whether residual immunity from smallpox vaccination provided cross-protection. To assess the cross-immune response to MPXV, we collected serum samples (n = 97) and PBMCs (n = 30) from healthy-donors, either born before 1974 and reporting smallpox vaccination during childhood or born after 1975 and not vaccinated with Vaccinia virus (VACV)-based vaccines. We evaluated the levels of anti-MPXV IgG and neutralizing antibodies (Nabs) and the presence of a T cell response against MPXV. We found anti-MPXV IgG and Nabs in 60 (89.6%) and 40 (70.1%) vaccinated individuals, respectively. We observed a T cell response to Orthopoxviruses and MPXV peptide pools in 30% of vaccinated individuals. We thus show that a high proportion of subjects who received the smallpox vaccine 40 to 60 years ago have humoral cross-immunity, while the T-cell-specific response against MPXV was observed in a smaller group (30%) of vaccinated individuals. This study, combined with information on immunity developed during natural infection or the administration of current vaccines, will contribute to a better understanding of humoral and cellular responses against MPXV.

Detection of Anti-Rift Valley Fever Virus Antibodies in Serum Samples of Patients with Suspected Arbovirus Infection.

The definitive diagnosis of the Rift Valley fever virus (RVFV) requires a form of testing that is available only in reference laboratories. It includes indirect immunofluorescence assay (IFA), the serum neutralization assay (NA), and real-time PCR. Therefore, often, no attempts are made to detect it, even among travelers from endemic areas. In this study, the presence of anti-RVFV IgG and IgM was retrospectively screened in stored serum samples from people who were admitted with arbovirus symptoms at the National Institute for Infectious Diseases (INMI) L. Spallanzani, Rome, Italy. Overall, 80 residual serum samples were anonymized, and sub-aliquots were prepared and tested for anti-RVFV IgG and IgM. A serum neutralization assay was used as a confirmatory test. There was a positive result in eight out of 80 samples (10%) for anti-RVFV IgG, with titers ranging from 1:40 up to 1:1280. Three of eight (2.6%) samples were confirmed as seropositive through an in-house serum neutralization assay, with antibody titers ranging from 1:10 to 1:160. All samples resulted negative for anti-RVFV IgM and RVFV RNA when tested by IFA and real-time RT-PCR, respectively. Our data highlight that several RVFV infections can possibly escape routine virological diagnosis, which suggests RVFV testing should be set up in order to monitor virus prevalence.

Profiling the acute phase antibody response against mpox virus in patients infected during the 2022 outbreak.

Information on the immune response during the mpox virus (MPXV) infection is still scarce or limited to past studies when cross-reactive immunity from smallpox vaccination was predominant. Here, we describe the short-term kinetics of the antibody response in patients with acute MPXV infection during the 2022 multicountry outbreak. A total of 64 samples from 18 MPXV-positive patients were longitudinally collected from the day of symptom onset (DSO) up to 20 days after and tested for anti-MPXV immunoglobulin G (IgG), IgM, IgA, and neutralizing antibodies (nAb) using the whole-live virus isolated in May 2022. IgG, IgM, and IgA were detected as early as 4 DSO (median time of seroconversion 7.5 DSO for IgG, 8 DSO for IgM and IgA). Anti-MPXV nAb were detectable in samples collected as early as 1 week after symptoms, with stable levels up to 20 DSO. After 2 weeks, IgG and nAb reached high titers. No significant differences were observed regardless of status of smallpox vaccination, human immunodeficiency virus positivity, or disease severity. Significant lower levels of IgM and IgG were observed in the patients treated with antivirals. These results contribute to extending the knowledge of the MPXV infection and the antibody response in a population with no historic smallpox vaccination.

Recovery from Triple Infection with SARS-CoV-2, RSV and Influenza virus: A case report.

The overall probability of infection with RSV, influenza virus, or SARS-CoV-2 in the general population is assessed as high by the ECDC. A high level of respiratory virus circulation increases hospitalizations and places significant pressure on healthcare systems. Here we describe the case of a 52-year-old woman who recovered from pneumonia with a triple infection with SARS-CoV-2, RSV, and Influenza virus. We suggest searching for antigenic or molecular detection of VSR and influenza viruses, together with SARS-CoV-2, in patients with respiratory symptoms during this epidemic period, whereas all three viruses are present right now.

Dynamic Evolution of Humoral and T-Cell Specific Immune Response to COVID-19 mRNA Vaccine in Patients with Multiple Sclerosis Followed until the Booster Dose.

This study characterizes antibody and T-cell immune responses over time until the booster dose of COronaVIrus Disease 2019 (COVID-19) vaccines in patients with multiple sclerosis (PwMS) undergoing different disease-modifying treatments (DMTs). We prospectively enrolled 134 PwMS and 99 health care workers (HCWs) having completed the two-dose schedule of a COVID-19 mRNA vaccine within the last 2-4 weeks (T0) and followed them 24 weeks after the first dose (T1) and 4-6 weeks after the booster (T2). PwMS presented a significant reduction in the seroconversion rate and anti-receptor-binding domain (RBD)-Immunoglobulin (IgG) titers from T0 to T1 (p < 0.0001) and a significant increase from T1 to T2 (p < 0.0001). The booster dose in PwMS showed a good improvement in the serologic response, even greater than HCWs, as it promoted a significant five-fold increase of anti-RBD-IgG titers compared with T0 (p < 0.0001). Similarly, the T-cell response showed a significant 1.5- and 3.8-fold increase in PwMS at T2 compared with T0 (p = 0.013) and T1 (p < 0.0001), respectively, without significant modulation in the number of responders. Regardless of the time elapsed since vaccination, most ocrelizumab- (77.3%) and fingolimod-treated patients (93.3%) showed only a T-cell-specific or humoral-specific response, respectively. The booster dose reinforces humoral- and cell-mediated-specific immune responses and highlights specific DMT-induced immune frailties, suggesting the need for specifically tailored strategies for immune-compromised patients to provide primary prophylaxis, early SARS-CoV-2 detection and the timely management of COVID-19 antiviral treatments.

Diagnostics of Ebola virus.

Ebola is a highly pathogenic virus, which in humans reaches a mortality rate above 50%. Due to a lack of laboratories in territories where Ebola viruses are endemic and the limited number of surveillance programmes, tests for the confirmation of suspected cases of Ebola are often performed in Reference Laboratories. While this provides guarantees regarding the accuracy of results, the shipment of samples to a centralized facility where the diagnostic test can be performed and the time required to achieve the results takes several days, which increases costs and entails delays in the isolation of positive subjects and therapeutic intervention with negative consequences both for patients and the community. Molecular tests have been the most frequently used tool in Ebola diagnosis in recent outbreaks. One of the most commonly used molecular tests is the Real-Star Altona, which targets a conserved area of the L gene. This assay showed different sensitivities depending on the Ebola virus: 471 copies/mL (EBOV) and 2871 copies/ml (SUDAN virus). The Cepheid system also showed good sensitivity (232 copies/mL). The LAMP platform is very promising because, being an isothermal reaction, it does not require high-precision instrumentation and can be considered a Point of Care (PoC) tool. Its analytical sensitivity is 1 copy/reaction. However, since data from real life studies are not yet available, it is premature to give any indications on its feasibility. Moreover, in November 2014, the WHO recommended the development of rapid diagnostic tests (RDT) according to ASSURED criteria. Several RDT assays have since been produced, most of which are rapid tests based on the search for antibody anti-Ebola viral proteins with immunochromatographic methods. Several viral antigens are used for this purpose: VP40, NP and GP. These assays show different sensitivities according to the protein used: VP40 57.4-93.1%, GP 53-88.9% and 85% for NP compared to reference molecular assays. From these results, it can be deduced that no RDT reaches the 99% sensitivity recommended by the WHO and therefore any RDT negative results in suspected cases should be confirmed with a molecular test.

Kinetics of viral DNA in body fluids and antibody response in patients with acute Monkeypox virus infection.

We report the follow-up laboratory investigation of three MPXV cases infected in May-June 2022 from diagnosis to disease resolution, monitoring viral shedding in different body fluids and antibody kinetics. Out of 138 non-lesion samples, viral DNA was found in 92.3% saliva, 85.7% semen, 86.2% oropharyngeal swabs, 51.7% plasma, 46.1% stool, and 9.5% urine samples. Viral load quantified by digital PCR widely varied, but tend to be higher in oropharyngeal swabs, saliva, and stool. Replication competent virus was recovered from four out of seventeen samples, including 1 saliva, 1 oropharyngeal swabs, 1 semen, and 1 stool. The analysis of the antibody kinetics revealed that IgM, IgA, and IgG antibodies were detected within two weeks post-symptoms onset for all three patients, with IgG detected early on at day 4-8 and IgM and IgA showing lower titers along the time frame of the study. Antibody levels increased during the second week of illness with IgG reaching high titers.

Longitudinal characterisation of B and T-cell immune responses after the booster dose of COVID-19 mRNA-vaccine in people with multiple sclerosis using different disease-modifying therapies.

BACKGROUND: The decline of humoral response to COVID-19 vaccine led to authorise a booster dose. Here, we characterised the kinetics of B-cell and T-cell immune responses in patients with multiple sclerosis (PwMS) after the booster dose. METHODS: We enrolled 22 PwMS and 40 healthcare workers (HCWs) after 4-6 weeks from the booster dose (T3). Thirty HCWs and 19 PwMS were also recruited 6 months (T2) after the first dose. Antibody response was measured by anti-receptor-binding domain (RBD)-IgG detection, cell-mediated response by an interferon (IFN)-γ release assay (IGRA), Th1 cytokines and T-cell memory profile by flow cytometry. RESULTS: Booster dose increased anti-RBD-IgG titers in fingolimod-treated, cladribine-treated and IFN-ß-treated patients, but not in ocrelizumab-treated patients, although antibody titres were lower than HCWs. A higher number of fingolimod-treated patients seroconverted at T3. Differently, T-cell response evaluated by IGRA remained stable in PwMS independently of therapy. Spike-specific Th1-cytokine response was mainly CD4+ T-cell-mediated, and in PwMS was significantly reduced (p<0.0001) with impaired IL-2 production compared with HCWs at T3. In PwMS, total Th1 and IFN-γ CD4+ T-cell responders to spike protein were increased from T2 to T3.Compared with HCWs, PwMS presented a higher frequency of CD4+ and CD8+ terminally differentiated effector memory cells and of CD4+ effector memory (TEM) cells, independently of the stimulus suggesting the association of this phenotype with MS status. CD4+ and CD8+ TEM cell frequency was further increased at T3 compared with T2. CONCLUSIONS: COVID-19 vaccine booster strengthens humoral and Th1-cell responses and increases TEM cells in PwMS.

Booster dose of SARS-CoV-2 messenger RNA vaccines strengthens the specific immune response of patients with rheumatoid arthritis: A prospective multicenter longitudinal study.

OBJECTIVES: To characterize the kinetics of humoral and T-cell responses in rheumatoid arthritis (RA)-patients followed up to 4-6 weeks (T3) after the SARS-CoV-2 vaccine booster dose. METHODS: Health care workers (HCWs, n = 38) and patients with RA (n = 52) completing the messenger RNA vaccination schedule were enrolled at T3. In each cohort, 25 subjects were sampled after 5 weeks (T1) and 6 months (T2) from the first vaccine dose. The humoral response was assessed by measuring anti-receptor-binding domain (RBD) and neutralizing antibodies, the T-cell response by interferon-γ-release assay (IGRA), T cell cytokine production, and B cell phenotype at T3 by flow cytometry. RESULTS: Patients with RA showed a significant reduction of antibody titers from T1 to T2 and a significant increase at T3. T-cell response by IGRA persisted over time in patients with RA, whereas it increased in HCWs. Most patients with RA scored positive for anti-RBD, neutralizing antibody and T-cell responses, although the magnitude was lower than HCWs. The spike-specific-cytokine response was mainly clusters of differentiation (CD)4+ T cells restricted in both cohorts and significantly lower with reduced interleukin-2 response and CD4-antigen-responding naïve T cells in patients with RA. Unswitched memory B cells were reduced in patients with RA compared with HCWs independently of vaccination. CONCLUSION: COVID-19 vaccine booster strengthens the humoral immunity in patients with RA even with a reduced cytokine response.

Comparative analysis of the neutralizing activity against SARS-CoV-2 Wuhan-Hu-1 strain and variants of concern: Performance evaluation of a pseudovirus-based neutralization assay.

Objectives: Emergence of new variants of SARS-CoV-2 might affect vaccine efficacy. Therefore, assessing the capacity of sera to neutralize variants of concern (VOCs) in BSL-2 conditions will help evaluating the immune status of population following vaccination or infection. Methods: Pseudotyped viruses bearing SARS-CoV-2 spike protein from Wuhan-Hu-1/D614G strains (wild type, WT), B.1.617.2 (Delta), or B.1.1.529 (Omicron) VOCs were generated to assess the neutralizing antibodies (nAbs) activity by a pseudovirus-based neutralization assay (PVNA). PVNA performance was assessed in comparison to the micro-neutralization test (MNT) based on live viruses. Sera collected from COVID-19 convalescents and vaccinees receiving mRNA (BNT16b2 or mRNA-1273) or viral vector (AZD1222 or Ad26.COV2.S) vaccines were used to measure nAbs elicited by two-dose BNT16b2, mRNA-1273, AZD1222 or one-dose Ad26.CO2.S, at different times from completed vaccination, ~ 1.5 month and ~ 4-6 months. Sera from pre-pandemic and unvaccinated individuals were analyzed as controls. Neutralizing activity following booster vaccinations against VOCs was also determined. Results: PVNA titers correlated with the gold standard MNT assay, validating the reliability of PVNA. Sera analyzed late from the second dose showed a reduced neutralization activity compared to sera collected earlier. Ad26.CO2.S vaccination led to very low or absent nAbs. Neutralization of Delta and Omicron BA.1 VOCs showed significant reduction of nAbs respect to WT strain. Importantly, booster doses enhanced Omicron BA.1 nAbs, with persistent levels at 3 months from boosting. Conclusions: PVNA is a reliable tool for assessing anti-SARS-CoV-2 nAbs helping the establishment of a correlate of protection and the management of vaccination strategies.

External quality assessment of SARS-CoV-2 serology in European expert laboratories, April 2021.

BackgroundCountries worldwide are focusing to mitigate the ongoing SARS-CoV-2 pandemic by employing public health measures. Laboratories have a key role in the control of SARS-CoV-2 transmission. Serology for SARS-CoV-2 is of critical importance to support diagnosis, define the epidemiological framework and evaluate immune responses to natural infection and vaccine administration.AimThe aim of this study was the assessment of the actual capability among laboratories involved in sero-epidemiological studies on COVID-19 in EU/EEA and EU enlargement countries to detect SARS-CoV-2 antibodies through an external quality assessment (EQA) based on proficiency testing.MethodsThe EQA panels were composed of eight different, pooled human serum samples (all collected in 2020 before the vaccine roll-out), addressing sensitivity and specificity of detection. The panels and two EU human SARS-CoV-2 serological standards were sent to 56 laboratories in 30 countries.ResultsThe overall performance of laboratories within this EQA indicated a robust ability to establish past SARS-CoV-2 infections via detection of anti-SARS-CoV-2 antibodies, with 53 of 55 laboratories using at least one test that characterised all EQA samples correctly. IgM-specific test methods provided most incorrect sample characterisations (24/208), while test methods detecting total immunoglobulin (0/119) and neutralising antibodies (2/230) performed the best. The semiquantitative assays used by the EQA participants also showed a robust performance in relation to the standards.ConclusionOur EQA showed a high capability across European reference laboratories for reliable diagnostics for SARS-CoV-2 antibody responses. Serological tests that provide robust and reliable detection of anti-SARS-CoV-2 antibodies are available.

Safety and immune response kinetics of GRAd-COV2 vaccine: phase 1 clinical trial results.

Despite the successful deployment of efficacious vaccines and therapeutics, the development of novel vaccines for SARS-CoV-2 remains a major goal to increase vaccine doses availability and accessibility for lower income setting. We report here on the kinetics of Spike-specific humoral and T-cell response in young and old volunteers over 6 months follow-up after a single intramuscular administration of GRAd-COV2, a gorilla adenoviral vector-based vaccine candidate currently in phase-2 of clinical development. At all three tested vaccine dosages, Spike binding and neutralizing antibodies were induced and substantially maintained up to 3 months, to then contract at 6 months. Potent T-cell responses were readily induced and sustained throughout the study period, with only minor decline. No major differences in immune response to GRAd-COV2 vaccination were observed in the two age cohorts. In light of its favorable safety and immunogenicity, GRAd-COV2 is a valuable candidate for further clinical development and potential addition to the COVID-19 vaccine toolbox to help fighting SARS-CoV-2 pandemic.