COVID-19 seroprevalence among local authority workers from Orléans Métropole, the Community of Communes of the Terres du Val de Loire, the local public service management centre of the Loiret department and the Region Centre Val de Loire: a prospective epidemiological study.

OBJECTIVE: To evaluate the SARS-CoV-2 seroprevalence among local authority workers, depending on their position and potential interaction with the public. METHODS: A cohort of volunteer participants was recruited among local authority workers of the Centre Val de Loire region in France, to be tested using a rapid serological test (COVID-PRESTO). The collected data were analysed by comparing different parameters including, gender, age, position held, and contact or not with the public. The study was carried out from August to December 2020 and included 3228 participants (n=3228), from 18 to 65 years old. RESULTS: The seroprevalence of SARS-CoV-2 among local authority workers was estimated at 3.04%. No significant difference could be observed according to the position held by the workers and whether they were or not in contact with the public. Nevertheless, a significant difference was observed between the different investigating centres, in correlation with the geographical location. CONCLUSION: Contact with members of the public was not a critical parameter for SARS-CoV-2 seroprevalence as long as protective measures are applied. Among the population included in the study, childcare workers were more at risk of getting infected by the virus. TRIAL REGISTRATION NUMBER: NCT04387968.

Resistance of Omicron subvariants BA.2.75.2, BA.4.6, and BQ.1.1 to neutralizing antibodies.

Convergent evolution of SARS-CoV-2 Omicron BA.2, BA.4, and BA.5 lineages has led to the emergence of several new subvariants, including BA.2.75.2, BA.4.6. and BQ.1.1. The subvariant BQ.1.1 became predominant in many countries in December 2022. The subvariants carry an additional and often redundant set of mutations in the spike, likely responsible for increased transmissibility and immune evasion. Here, we established a viral amplification procedure to easily isolate Omicron strains. We examined their sensitivity to 6 therapeutic monoclonal antibodies (mAbs) and to 72 sera from Pfizer BNT162b2-vaccinated individuals, with or without BA.1/BA.2 or BA.5 breakthrough infection. Ronapreve (Casirivimab and Imdevimab) and Evusheld (Cilgavimab and Tixagevimab) lose antiviral efficacy against BA.2.75.2 and BQ.1.1, whereas Xevudy (Sotrovimab) remaine weakly active. BQ.1.1 is also resistant to Bebtelovimab. Neutralizing titers in triply vaccinated individuals are low to undetectable against BQ.1.1 and BA.2.75.2, 4 months after boosting. A BA.1/BA.2 breakthrough infection increases these titers, which remains about 18-fold lower against BA.2.75.2 and BQ.1.1, than against BA.1. Reciprocally, a BA.5 breakthrough infection increases more efficiently neutralization against BA.5 and BQ.1.1 than against BA.2.75.2. Thus, the evolution trajectory of novel Omicron subvariants facilitates their spread in immunized populations and raises concerns about the efficacy of most available mAbs.

Longitudinal analysis of serum neutralization of SARS-CoV-2 Omicron BA.2, BA.4, and BA.5 in patients receiving monoclonal antibodies.

The emergence of Omicron sublineages impacts the therapeutic efficacy of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) monoclonal antibodies (mAbs). Here, we evaluate neutralization and antibody-dependent cellular cytotoxicity (ADCC) activities of 6 therapeutic mAbs against Delta, BA.2, BA.4, and BA.5. The Omicron subvariants escape most antibodies but remain sensitive to bebtelovimab and cilgavimab. Consistent with their shared spike sequence, BA.4 and BA.5 display identical neutralization profiles. Sotrovimab is the most efficient at eliciting ADCC. We also analyze 121 sera from 40 immunocompromised individuals up to 6 months after infusion of Ronapreve (imdevimab + casirivimab) or Evusheld (cilgavimab + tixagevimab). Sera from Ronapreve-treated individuals do not neutralize Omicron subvariants. Evusheld-treated individuals neutralize BA.2 and BA.5, but titers are reduced. A longitudinal evaluation of sera from Evusheld-treated patients reveals a slow decay of mAb levels and neutralization, which is faster against BA.5. Our data shed light on antiviral activities of therapeutic mAbs and the duration of effectiveness of Evusheld pre-exposure prophylaxis.

Duration of BA.5 neutralization in sera and nasal swabs from SARS-CoV-2 vaccinated individuals, with or without omicron breakthrough infection.

BACKGROUND: Since early 2022, Omicron BA.1 has been eclipsed by BA.2, which was in turn outcompeted by BA.5, which displays enhanced antibody escape properties. METHODS: Here, we evaluated the duration of the neutralizing antibody (Nab) response, up to 18 months after Pfizer BNT162b2 vaccination, in individuals with or without BA.1/BA.2 breakthrough infection. We measured neutralization of the ancestral D614G lineage, Delta, and Omicron BA.1, BA.2, and BA.5 variants in 300 sera and 35 nasal swabs from 27 individuals. FINDINGS: Upon vaccination, serum Nab titers were decreased by 10-, 15-, and 25-fold for BA.1, BA.2, and BA.5, respectively, compared with D614G. We estimated that, after boosting, the duration of neutralization was markedly shortened from 11.5 months with D614G to 5.5 months with BA.5. After breakthrough, we observed a sharp increase of Nabs against Omicron subvariants, followed by a plateau and a slow decline after 5-6 months. In nasal swabs, infection, but not vaccination, triggered a strong immunoglobulin A (IgA) response and a detectable Omicron-neutralizing activity. CONCLUSIONS: BA.5 spread is partly due to abbreviated vaccine efficacy, particularly in individuals who were not infected with previous Omicron variants. FUNDING: Work in O.S.'s laboratory is funded by the Institut Pasteur, Urgence COVID-19 Fundraising Campaign of Institut Pasteur, Fondation pour la Recherche Médicale (FRM), ANRS, the Vaccine Research Institute (ANR-10-LABX-77), Labex IBEID (ANR-10-LABX-62-IBEID), ANR/FRM Flash Covid PROTEO-SARS-CoV-2, ANR Coronamito, and IDISCOVR, Laboratoire d'Excellence 'Integrative Biology of Emerging Infectious Diseases' (grant no. ANR-10-LABX-62-IBEID), HERA european funding and the NIH PICREID (grant no U01AI151758).

Lectin Analysis of SARS-CoV-2-Positive Nasopharyngeal Samples Using GLYcoPROFILE® Technology Platform.

Nasopharyngeal samples are currently accepted as the standard diagnostic samples for nucleic acid amplification testing and antigenic testing for the SARS-CoV-2 virus. In addition to the diagnostic capacity of SARS-CoV-2-positive crude nasopharyngeal samples, their qualitative potential for direct glycan-specific analysis, in order to uncover unique glycol profiles, was assessed. In this study we provide glycan characterization of SARS-CoV-2-positive and -negative nasopharyngeal samples directly from lectin interactions. Although with limited throughput, this study evaluated the clinical sensitivity and specificity of the GLYcoPROFILE® technology platformon45crude nasopharyngeal samples collected between November 2020 and April 2022. Each GLYcoPROFILE® of 39 SARS-CoV-2-positive samples was compared toglycoprofiling on a panel of 10 selected lectins and the results were paralleled with SARS-CoV-2-negative samples' results. The GLYcoPROFILE® showed a clear distinction between positive and negative samples with WFA, GSL-II, PHA-L (GlcNAc-specific) and BPA (GalNAc-specific) highlighted as relevant lectins in SARS-CoV-2-positive samples. In addition, a significant, positive statistical correlation was found for these lectins (p < 0.01).

Duration of BA.5 neutralization in sera and nasal swabs from SARS-CoV-2 vaccinated individuals, with or without Omicron breakthrough infection

Background Since early 2022, Omicron BA.1 has been eclipsed by BA.2, which was in turn outcompeted by BA.5, that displays enhanced antibody escape properties. Methods Here, we evaluated the duration of the neutralizing antibody (Nab) response, up to 18 months after Pfizer BNT162b2 vaccination, in individuals with or without BA.1/BA.2 breakthrough infection. We measured neutralization of the ancestral D614G lineage, Delta and Omicron BA.1, BA.2, BA.5 variants in 300 sera and 35 nasal swabs from 27 individuals. Findings Upon vaccination, serum Nab titers were reduced by 10-, 15- and 25-fold for BA.1, BA.2 and BA.5, respectively, compared with D614G. We estimated that after boosting, the duration of neutralization was markedly shortened from 11.5 months with D614G to 5.5 months with BA.5. After breakthrough, we observed a sharp increase of Nabs against Omicron subvariants, followed by a plateau and a slow decline after 5-6 months. In nasal swabs, infection, but not vaccination, triggered a strong IgA response and a detectable Omicron neutralizing activity. Conclusions Thus, BA.5 spread is partly due to abbreviated vaccine efficacy, particularly in individuals who were not infected with previous Omicron variants. Funding Work in OS lab is funded by Institut Pasteur, Urgence COVID-19 Fundraising Campaign of Institut Pasteur, Fondation pour la Recherche Médicale (FRM), ANRS, the Vaccine Research Institute (ANR-10-LABX-77), Labex IBEID (ANR-10-LABX-62-IBEID), ANR/FRM Flash Covid PROTEO-SARS-CoV-2, ANR Coronamito, and IDISCOVR. Laboratoire d’Excellence ‘Integrative Biology of Emerging Infectious Diseases’ (grant no. ANR-10-LABX-62-IBEID) and the NIH PICREID (grant no U01AI151758). Graphical Planas et al analyze the extent and duration of the neutralizing antibody response following vaccination with Pfizer BNT162b2 mRNA in the sera and nasal swabs from individuals with or without Omicron breakthrough infection, finding a short duration of neutralization against BA.5 after boosting and strong IgA response upon breakthrough infection.

Kinetics of the SARS-CoV-2 Antibody Avidity Response Following Infection and Vaccination.

Serological assays capable of measuring antibody responses induced by previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been critical tools in the response to the COVID-19 pandemic. In this study, we use bead-based multiplex assays to measure IgG and IgA antibodies and IgG avidity to five SARS-CoV-2 antigens (Spike (S), receptor-binding domain (RBD), Nucleocapsid (N), S subunit 2, and Membrane-Envelope fusion (ME)). These assays were performed in several cohorts of healthcare workers and nursing home residents, who were followed for up to eleven months after SARS-CoV-2 infection or up to six months after vaccination. Our results show distinct kinetic patterns of antibody quantity (IgG and IgA) and avidity. While IgG and IgA antibody levels waned over time, with IgA antibody levels waning more rapidly, avidity increased with time after infection or vaccination. These contrasting kinetic patterns allow for the estimation of time since previous SARS-CoV-2 infection. Including avidity measurements in addition to antibody levels in a classification algorithm for estimating time since infection led to a substantial improvement in accuracy, from 62% to 78%. The inclusion of antibody avidity in panels of serological assays can yield valuable information for improving serosurveillance during SARS-CoV-2 epidemics.

Evaluation of a new "all in one" SARS-CoV-2 antigen-detecting rapid diagnostic test and self-test: Diagnostic performance and usability in child and adult populations.

The control of the COVID-19 epidemics has been one global health priorities for the last 2 years. To that end, more reliable and easy-to-use, regardless of age, diagnostic tests are necessary. Considering that, we evaluated an innovative two-step self-test, the AAZ COVID-VIRO ALL IN®, switching from the classic nasal swab to a nasal sponge. We performed a multicenter study, on 124 adults and children, in a point-of-care setting. Sensitivity, specificity and overall acceptance of the COVID-VIRO ALL IN® self-test compared to reverse transcriptase polymerase chain reaction (RT-PCR) on nasopharyngeal samples were of 93.0%, 100%, and 97.5%, respectively. We then performed a multicenter, usability study to evaluate the ease of use of COVID-VIRO ALL IN® on 68 laypersons adults. A vast majority of participants correctly executed and interpreted the test. The usability was then specifically investigated on 40 children and teenagers, comparing COVID-VIRO® first generation to the new COVID-VIRO ALL IN®. They all found COVID-VIRO ALL IN® more comfortable and easier to use. For young children, the new self-test seems safer (less risk of trauma and no liquid exposure), and faster than saliva-based RT-PCR. Moreover, the COVID-VIRO ALL IN® can easily be adapted as a multiplex self-test for other respiratory viruses, opening new perspectives of simultaneous, rapid and massive detection of respiratory infections, especially among vulnerable populations like children and elderly people.

Serum neutralization of SARS-CoV-2 Omicron sublineages BA.1 and BA.2 in patients receiving monoclonal antibodies.

The severe acute respiratory syndrome coronavirus 2 Omicron BA.1 sublineage has been supplanted in many countries by the BA.2 sublineage. BA.2 differs from BA.1 by about 21 mutations in its spike. In this study, we first compared the sensitivity of BA.1 and BA.2 to neutralization by nine therapeutic monoclonal antibodies (mAbs). In contrast to BA.1, BA.2 was sensitive to cilgavimab, partly inhibited by imdevimab and resistant to adintrevimab and sotrovimab. We then analyzed sera from 29 immunocompromised individuals up to 1 month after administration of Ronapreve (casirivimab and imdevimab) and/or Evusheld (cilgavimab and tixagevimab) antibody cocktails. All treated individuals displayed elevated antibody levels in their sera, which efficiently neutralized the Delta variant. Sera from Ronapreve recipients did not neutralize BA.1 and weakly inhibited BA.2. Neutralization of BA.1 and BA.2 was detected in 19 and 29 out of 29 Evusheld recipients, respectively. As compared to the Delta variant, neutralizing titers were more markedly decreased against BA.1 (344-fold) than BA.2 (nine-fold). We further report four breakthrough Omicron infections among the 29 individuals, indicating that antibody treatment did not fully prevent infection. Collectively, BA.1 and BA.2 exhibit noticeable differences in their sensitivity to therapeutic mAbs. Anti-Omicron neutralizing activity of Ronapreve and, to a lesser extent, that of Evusheld is reduced in patients' sera.

Fusogenicity and neutralization sensitivity of the SARS-CoV-2 Delta sublineage AY.4.2.

BACKGROUND: SARS-CoV-2 lineages are continuously evolving. As of December 2021, the AY.4.2 Delta sub-lineage represented 20 % of sequenced strains in the UK and had been detected in dozens of countries. It has since then been supplanted by Omicron. The AY.4.2 spike displays three additional mutations (T95I, Y145H and A222V) in the N-terminal domain when compared to the original Delta variant (B.1.617.2) and remains poorly characterized. METHODS: We compared the Delta and the AY.4.2 spikes, by assessing their binding to antibodies and ACE2 and their fusogenicity. We studied the sensitivity of an authentic AY.4.2 viral isolate to neutralizing antibodies. FINDINGS: The AY.4.2 spike exhibited similar binding to all the antibodies and sera tested, and similar fusogenicity and binding to ACE2 than the ancestral Delta spike. The AY.4.2 virus was slightly less sensitive than Delta to neutralization by a panel of monoclonal antibodies; noticeably, the anti-RBD Imdevimab showed incomplete neutralization. Sensitivity of AY.4.2 to sera from vaccinated individuals was reduced by 1.3 to 3-fold, when compared to Delta. INTERPRETATION: Our results suggest that mutations in the NTD remotely impair the efficacy of anti-RBD antibodies. The spread of AY.4.2 was not due to major changes in spike fusogenicity or ACE2 binding, but more likely to a partially reduced neutralization sensitivity. FUNDING: The work was funded by Institut Pasteur, Fondation pour la Recherche Médicale, Urgence COVID-19 Fundraising Campaign of Institut Pasteur, ANRS, the Vaccine Research Institute, Labex IBEID, ANR/FRM Flash Covid PROTEO-SARS-CoV-2 and IDISCOVR.

Maternal-Fetal Implications of SARS CoV-2 Infection during Pregnancy, Viral, Serological Analyses of Placenta and Cord Blood.

OBJECTIVE: There are few data on the maternal-fetal transmission of SARS-CoV-2 and its outcomes. This study aimed to evaluate pregnancy outcomes of pregnant women infected by SARS-CoV-2, to detect SARS-CoV-2 in placenta and different newborns' samples and search antibodies in cord blood. METHODS: This was a prospective study of pregnant women diagnosed with SARS-CoV-2 infection from May 2020 to May 2021. At delivery, the placentas were investigated for SARS-CoV-2 using RT-PCR, cord blood. Mothers' blood samples were tested by SARS-CoV-2 serology. PCR of nasopharyngeal, anal and gastric swabs (NPSs) of newborns was performed according to pediatric indications. RESULTS: Among 3626 pregnant women presenting at maternity to deliver, 45 mothers had COVID-19 during their pregnancy or at delivery (32 ± 4.8 years). Most of them were multiparous and in the third trimester. There were 35 (77%) women who remained in ambulatory, while 10 (22%) were hospitalized for severe pneumonia, digestive symptoms, and/or fetal tachycardia. Thirty-eight delivered vaginally, and 7 had a cesarean delivery with normal Apgar scores (9 ± 1.6 at 5 min) and umbilical artery pH (7.22 ± 0.08). Two mothers required ICU admission after cesarean section for fetal and maternal distress. Of the 46 newborns, 6 were premature births (13%) and 5 IUGR (intra-uterine growth restriction,11%). RT-PCR SARS-CoV-2 was positive for 1/30 placental, and 1/33 neonatal anal swabs and negative in all other cases and in gastric swabs. SARS-CoV-2 IgG was positive in 20/41 cord blood samples (49%) and their mothers' samples. IgM was negative in the 23 cord blood samples. CONCLUSIONS: Pregnancy outcomes in women diagnosed with COVID-19 during their pregnancy were favorable in most cases. However, some women with severe clinical forms required hospitalization and ICU admission. Preterm births and intrauterine growth retardations were relatively frequent. Vaginal delivery was possible in most cases. SARS-CoV-2 IgG antibodies were positive and elevated in most cord blood samples of newborns. They are possibly of maternal origin, suggesting a probable mechanism of fetal protection against SARS-CoV-2 infection. No SARS-CoV-2 IgM was found in the cord blood samples. Detection of SARS-CoV-2 in placenta is rare.

Considerable escape of SARS-CoV-2 Omicron to antibody neutralization.

The SARS-CoV-2 Omicron variant was first identified in November 2021 in Botswana and South Africa1-3. It has since spread to many countries and is expected to rapidly become dominant worldwide. The lineage is characterized by the presence of around 32 mutations in spike-located mostly in the N-terminal domain and the receptor-binding domain-that may enhance viral fitness and enable antibody evasion. Here we isolated an infectious Omicron virus in Belgium from a traveller returning from Egypt. We examined its sensitivity to nine monoclonal antibodies that have been clinically approved or are in development4, and to antibodies present in 115 serum samples from COVID-19 vaccine recipients or individuals who have recovered from COVID-19. Omicron was completely or partially resistant to neutralization by all monoclonal antibodies tested. Sera from recipients of the Pfizer or AstraZeneca vaccine, sampled five months after complete vaccination, barely inhibited Omicron. Sera from COVID-19-convalescent patients collected 6 or 12 months after symptoms displayed low or no neutralizing activity against Omicron. Administration of a booster Pfizer dose as well as vaccination of previously infected individuals generated an anti-Omicron neutralizing response, with titres 6-fold to 23-fold lower against Omicron compared with those against Delta. Thus, Omicron escapes most therapeutic monoclonal antibodies and, to a large extent, vaccine-elicited antibodies. However, Omicron is neutralized by antibodies generated by a booster vaccine dose.

Evaluation of a SARS-CoV-2 antigen-detecting rapid diagnostic test as a self-test: Diagnostic performance and usability.

To control the spread of the coronavirus disease 2019 (COVID-19) epidemics, it is necessary to have easy-to-use, reliable diagnostic tests available. The nasopharyngeal sampling method being often uncomfortable, nasal sampling could prove to be a viable alternative to the reference sampling method. We performed a multicentre, prospective validation study of the COVID-VIRO® test, using a nasal swab sampling method, in a point-of-care setting. In addition, we performed a multicentre, prospective, and usability study to validate the use of the rapid antigen nasal diagnostic test by laypersons. In March 2021, 239 asymptomatic and symptomatic patients were included in the validation study. Compared with reverse-transcription polymerase chain reaction on nasopharyngeal samples, the sensitivity and specificity of the COVID-VIRO® Antigen test combined with a nasal sampling method were evaluated as 96.88% and 100%, respectively. A total of 101 individuals were included in the usability study. Among these, 99% of the participants rated the instructions material as good, 98% of the subjects executed the test procedure well, and 98% of the participants were able to correctly interpret the test results. This study validates the relevance of COVID-VIRO® as a diagnostic tool from nasal specimens as well as its usability in the general population. COVID-VIRO® diagnostic performances and ease of use make it suitable for widespread utilization.

Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization.

The SARS-CoV-2 B.1.617 lineage was identified in October 2020 in India1-5. Since then, it has become dominant in some regions of India and in the UK, and has spread to many other countries6. The lineage includes three main subtypes (B1.617.1, B.1.617.2 and B.1.617.3), which contain diverse mutations in the N-terminal domain (NTD) and the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein that may increase the immune evasion potential of these variants. B.1.617.2-also termed the Delta variant-is believed to spread faster than other variants. Here we isolated an infectious strain of the Delta variant from an individual with COVID-19 who had returned to France from India. We examined the sensitivity of this strain to monoclonal antibodies and to antibodies present in sera from individuals who had recovered from COVID-19 (hereafter referred to as convalescent individuals) or who had received a COVID-19 vaccine, and then compared this strain with other strains of SARS-CoV-2. The Delta variant was resistant to neutralization by some anti-NTD and anti-RBD monoclonal antibodies, including bamlanivimab, and these antibodies showed impaired binding to the spike protein. Sera collected from convalescent individuals up to 12 months after the onset of symptoms were fourfold less potent against the Delta variant relative to the Alpha variant (B.1.1.7). Sera from individuals who had received one dose of the Pfizer or the AstraZeneca vaccine had a barely discernible inhibitory effect on the Delta variant. Administration of two doses of the vaccine generated a neutralizing response in 95% of individuals, with titres three- to fivefold lower against the Delta variant than against the Alpha variant. Thus, the spread of the Delta variant is associated with an escape from antibodies that target non-RBD and RBD epitopes of the spike protein.

Effect of Tenofovir Disoproxil Fumarate and Emtricitabine on nasopharyngeal SARS-CoV-2 viral load burden amongst outpatients with COVID-19: A pilot, randomized, open-label phase 2 trial.

BACKGROUND: Tenofovir and emtricitabine interfere with the SARS CoV-2 ribonucleic acid (RNA)-dependent RNA polymerase (RdRp). Several cohorts reported that people treated by tenofovir disoproxil fumarate and emtricitabine are less likely to develop SARS CoV-2 infection and related severe COVID-19. METHODS: We conducted a pilot randomized, open-label, controlled, phase 2 trial at two hospitals in France. Eligible patients were consecutive outpatients (aged ≥18 years) with RT-PCR-confirmed SARS-CoV-2 infection and an interval from symptom onset to enrolment of 7 days or less. Patients were randomly assigned in a 1:1 ratio to receive oral tenofovir disoproxil fumarate and emtricitabine (2 pills on day 1 followed by 1 pill per day on days 2-7) or the standard of care. The primary and secondary endpoints were SARS-CoV-2 viral clearance from baseline assessed by cycle threshold (Ct) RT-PCR on nasopharyngeal swab collected at day 4 and day 7, respectively. A higher Ct corresponds to a lower SARS CoV-2 viral burden. Other endpoints were the time to recovery and the number of adverse events. This trial is registered with ClinicalTrials.gov, NCT04685512. FINDINGS: From November, 20th 2020 to March, 19th 2021, 60 patients were enrolled and randomly assigned to a treatment group (30 to tenofovir disoproxil fumarate and emtricitabine and 30 to standard of care). The median number of days from symptom onset to inclusion was 4 days (IQR 3-5) in both groups. Amongst patients who received tenofovir disoproxil fumarate, the difference from standard of care in the increase in Ct RT-PCR from baseline was 2.3 (95% confidence interval [-0.6 to 5.2], p = 0.13) at day 4 and 2.9 (95% CI [0.1 to 5.2], p = 0.044) at day 7. At day 7, 6/30 in the tenofovir disoproxil fumarate and emtricitabine group and 3/30 in the standard of care group reported no COVID-related symptoms. Adverse events included 11 cases of gastrointestinal side effects (grade ≤ 2), three of which leaded to drug discontinuation. Three patients had COVID-19 related hospitalisation, no participant died. INTERPRETATION: In this pilot study of outpatients adult with recent non-severe COVID-19, tenofovir disoproxil fumarate plus emtricitabine appeared to accelerate the natural clearance of nasopharyngeal SARS-CoV-2 viral burden. These findings support the conduct of larger trials of tenofovir-based therapies for the prevention and early treatment of COVID-19. FUNDING: No external funding.

Sensitivity of infectious SARS-CoV-2 B.1.1.7 and B.1.351 variants to neutralizing antibodies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.7 and B.1.351 variants were first identified in the United Kingdom and South Africa, respectively, and have since spread to many countries. These variants harboring diverse mutations in the gene encoding the spike protein raise important concerns about their immune evasion potential. Here, we isolated infectious B.1.1.7 and B.1.351 strains from acutely infected individuals. We examined sensitivity of the two variants to SARS-CoV-2 antibodies present in sera and nasal swabs from individuals infected with previously circulating strains or who were recently vaccinated, in comparison with a D614G reference virus. We utilized a new rapid neutralization assay, based on reporter cells that become positive for GFP after overnight infection. Sera from 58 convalescent individuals collected up to 9 months after symptoms, similarly neutralized B.1.1.7 and D614G. In contrast, after 9 months, convalescent sera had a mean sixfold reduction in neutralizing titers, and 40% of the samples lacked any activity against B.1.351. Sera from 19 individuals vaccinated twice with Pfizer Cominarty, longitudinally tested up to 6 weeks after vaccination, were similarly potent against B.1.1.7 but less efficacious against B.1.351, when compared to D614G. Neutralizing titers increased after the second vaccine dose, but remained 14-fold lower against B.1.351. In contrast, sera from convalescent or vaccinated individuals similarly bound the three spike proteins in a flow cytometry-based serological assay. Neutralizing antibodies were rarely detected in nasal swabs from vaccinees. Thus, faster-spreading SARS-CoV-2 variants acquired a partial resistance to neutralizing antibodies generated by natural infection or vaccination, which was most frequently detected in individuals with low antibody levels. Our results indicate that B1.351, but not B.1.1.7, may increase the risk of infection in immunized individuals.

SARS-CoV-2 Infection in Ivory Coast: A Serosurveillance Survey among Gold Mine Workers.

Of the 107 million COVID-19 cases worldwide, less than 2 million have been reported in African countries. The aim of this study was to evaluate the seroprevalence of SARS-CoV-2 infection in Ivory Coast mine workers. From July 15 to October 13, 2020, a voluntary serological test campaign was conducted in 3 sites: two gold mines, and the headquarters in Abidjan. Rapid tests to detect IgG and IgM on capillary blood were performed. To identify independent sociodemographic characteristics associated with a higher SARS-CoV-2 seroprevalence rate, a multivariate logistic regression analysis was performed. A total of 1,687 subjects were tested; 91% were male (n = 1,536), and the mean age was 37 years. The overall seroprevalence was 25.1% (n = 422), ranging between 13.6% (11.2-16.1%), 34.4% (31.1-37.7%), and 34.7% (26.2-43.2%) in mine A, in mine B, and in Abidjan, respectively. Among the 422 seropositive subjects, 74 reported mild symptoms in the three previous months and one was hospitalized for severe COVID-19 infection. SARS-CoV-2 seroprevalence is high in both gold miners and administrative staff working in Ivory Coast. The burden of infection in West Africa has probably been underestimated till now.

Evaluation of the practicability of a finger-stick whole-blood SARS-Cov-2 self-test adapted for the general population.

BACKGROUND: COVID-19 (COronaVIrus Disease 2019) is an infectious respiratory disease caused by the novel SARS-CoV-2 virus. Point of Care (POC) tests have been developed to detect specific antibodies, IgG and IgM, to SARS-CoV-2 virus in human whole blood. They need to be easily usable by the general population in order to alleviate the lockdown that many countries have initiated in response to the growing COVID-19 pandemic. A real-life study has been conducted in order to evaluate the performance of the COVID-PRESTO® POC test and the results were recently published. Even if this test showed very high sensitivity and specificity in a laboratory setting when used by trained professionals, it needs to be further evaluated for practicability when used by the general public in order to be approved by health authorities for in-home use. METHODS: 143 participants were recruited between March 2020 and April 2020 among non-medical populations in central France (nuclear plant workers, individuals attending the Orleans University Hospital vaccination clinic and Orleans University Hospital non-medical staff). Instructions for use, with or without a tutorial video, were made available to the volunteers. Two separate objectives were pursued: evaluation of the capability of participants to obtain an interpretable result, and evaluation of the users' ability to read the results. RESULTS: 88.4% of the test users judged the instructions for use leaflet to be clear and understandable. 99.3% of the users obtained a valid result and, according to the supervisors, 92.7% of the tests were properly performed by the users. Overall, 95% of the users gave positive feedback on the COVID PRESTO® as a potential self-test. Neither age nor education had an influence. CONCLUSION: COVID-PRESTO® was successfully used by an overwhelming majority of participants and its use was judged very satisfactory, therefore showing promising potential as a self-test to be used by the general population. This POC test can become an easy-to-use tool to help detect whether individuals are protected or not, particularly in the context of a second wave or a mass vaccination program.

Evaluation of performance of two SARS-CoV-2 Rapid IgM-IgG combined antibody tests on capillary whole blood samples from the fingertip.

BACKGROUND: The SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2) is responsible for the infectious respiratory disease called COVID-19 (COronaVIrus Disease 2019). In response to the growing COVID-19 pandemic, point-of-care (POC) tests have been developed to detect specific antibodies, IgG and IgM, to SARS-CoV-2 virus in human whole blood. We conducted a prospective observational study to evaluate the performance of two POC tests, COVID-PRESTO® and COVID-DUO®, compared to the gold standard, RT-PCR (real-time reverse transcriptase polymerase chain reaction). METHODS: RT-PCR testing of SARS-Cov-2 was performed from nasopharyngeal swab specimens collected in adult patients visiting the infectious disease department at the hospital (Orléans, France). Capillary whole blood (CWB) samples from the fingertip taken at different time points after onset of the disease were tested with POC tests. The specificity and sensitivity of the rapid test kits compared to test of reference (RT-PCR) were calculated. RESULTS: Among 381 patients with symptoms of COVID-19 who went to the hospital for a diagnostic, 143 patients were RT-PCR negative. Results of test with POC tests were all negative for these patients, indicating a specificity of 100% for both POC tests. In the RT-PCR positive subgroup (n = 238), 133 patients were tested with COVID-PRESTO® and 129 patients were tested with COVID-DUO® (24 patients tested with both). The further the onset of symptoms was from the date of collection, the greater the sensitivity. The sensitivity of COVID-PRESTO® test ranged from 10.00% for patients having experienced their 1st symptoms from 0 to 5 days ago to 100% in patients where symptoms had occurred more than 15 days before the date of tests. For COVID-DUO® test, the sensitivity ranged from 35.71% [0-5 days] to 100% (> 15 days). CONCLUSION: COVID-PRESTO® and DUO® POC tests turned out to be very specific (none false positive) and to be sensitive enough after 15 days from onset of symptom. These easy to use IgG/IgM combined test kits are the first ones allowing a screening with CWB sample, by typing from a finger prick. These rapid tests are particularly interesting for screening in low resource settings.