SARS-CoV-2-Spike T-cell response after receiving one or two Wuhan-Hu-1-based mRNA COVID-19 vaccine booster doses in elderly nursing home residents.

The effect of COVID-19 booster vaccination on SARS-CoV-2 T-cell mediated immune responses in elderly nursing home residents has not been explored in depth. Thirty-nine elderly nursing home residents (median age, 91 years) were included, all fully vaccinated with mRNA vaccines. The frequency of and the integrated mean fluorescence (iMFI) for peripheral blood SARS-CoV-2-Spike reactive IFN-γ-producing CD4+ or CD8+ T cells before and after the first (Pre-3D and Post-3D) and second (Pre-4D and Post-4D) vaccine booster doses was determined using flow cytometry for an intracellular staining method. 3D increased significantly (p = 0.01) the percentage of participants displaying detectable SARS-CoV-2-T-cell responses compared with pre-3D (97% vs. 74%). The magnitude of the increase was statistically significant for CD8+ T cells (p = 0.007) but not for CD4+ T cells (p = 0.77). A trend towards higher frequencies of peripheral blood SARS-CoV-2-CD8+ T cells was observed post-3D compared with pre-3D (p = 0.06). The percentage of participants with detectable SARS-S-CoV-2 CD4+ T-cell responses decreased post-4D (p = 0.035). Following 4D, a nonsignificant decrease in the frequencies of both T cell subsets was noticed (p = 0.94 for CD8+ T cells and p = 0.06 for CD4+ T cells). iMFI data mirrored that of T-cell frequencies. The kinetics of SARS-CoV-2 CD8+ and CD4+ T cells following receipt of 3D and 4D were comparable across SARS-CoV-2-experienced and -naïve participants and between individuals receiving a homologous or heterologous vaccine booster. 3D increased the percentage of elderly nursing home residents displaying detectable SARS-CoV-2 T-cell responses but had a marginal effect on T-cell frequencies. The impact of 4D on SARS-CoV-2 T-cell responses was negligible; whether this was due to suboptimal priming or rapid waning could not be ascertained.

Impact of the microscopic quality of endotracheal aspirates on the performance of the Filmarray® pneumonia plus panel in intensive care unit patients with suspected lower respiratory tract infection.

PURPOSE: We investigated how the microscopic quality of endotracheal aspirates (ETA) impacts the performance of the Filmarray® pneumonia plus panel (FA-PP) in patients undergoing mechanical ventilation (IMV) with suspicion of lower respiratory tract bacterial infection (LRTBI). METHODS: The quality of ETA was categorized according to the number of leukocytes and buccal squamous epithelial (BSE)/field (100x magnification). G5 (< 10 BSE cells and > 25 leukocytes/field) and G4 (10-25 BSE cells and > 25 leukocytes/field) ETA were tested in parallel by the FA-PP and conventional semiquantitative culture. RESULTS: In total, 153 ETA were graded as G5 (from 115 patients) and 56 as G4 (from 48 patients). Focusing on "conventional" bacterial species, a trend towards more positive results (P = 0.16), and co-detections (P = 0.18) was returned by G5 ETA. Although more targets were detected on G5 ETA (P = 0.005), the spectra of bacteria detected was comparable across G5 and G4 specimens. A trend towards higher bacterial burdens as quantitated by the FA-PP, and irrespective of the target, was observed in G5 (median, 106 genome copies/ml) vs. G4 ETA (median, 105 genome copies/ml). The degree of full agreement between FA-PP and culture was higher for G5 ETA (Kappa value, 0.54; 95% CI, 0.43-0.66) than for G4 ETA (Kappa value, 0.31; 95% CI, 0.11-0.49). For all bacterial targets detected, genome copy/ml numbers exceeded colony forming units (CFU)/ml counts in 1-2 log10, irrespective of ETA grading. The degree of correlation between genome copies/ml and CFU/ml was slightly better for G5 ETA (Rho = 0.65; P = 0.001) than for G4 ETA (Rho = 0.54; P = 0.11). CONCLUSION: FA-PP testing of G5 ETA may provide more comprehensive and clinically useful information compared with G4 specimens in patients undergoing IMV with suspected LRTBI and receiving antimicrobial therapy. Yet G4 ETA may still provide useful microbiological information.

A performance comparison of two (electro) chemiluminescence immunoassays for detection and quantitation of serum anti-spike antibodies according to SARS-CoV-2 vaccination and infections status.

The information provided by SARS-CoV-2 spike (S)-targeting immunoassays can be instrumental in clinical-decision making. We compared the performance of the Elecsys® Anti-SARS-CoV-2 S assay (Roche Diagnostics) and the LIAISON® SARS-CoV-2 TrimericS IgG assay (DiaSorin) using a total of 1176 sera from 797 individuals, of which 286 were from vaccinated-SARS-CoV-2/experienced (Vac-Ex), 581 from vaccinated/naïve (Vac-N), 147 from unvaccinated/experienced (Unvac-Ex), and 162 from unvaccinated/naïve (Unvac-N) individuals. The Roche assay returned a higher number of positive results (907 vs. 790; p = 0.45; overall sensitivity: 89.3% vs. 77.6%). The concordance between results provided by the two immunoassays was higher for sera from Vac-N (Ï°: 0.58; interquartile ranges [IQR]: 0.50-0.65) than for sera from Vac-Ex (Ï°: 0.19; IQR: -0.14 to 0.52) or Unvac-Ex (Ï°: 0.18; IQR: 0.06-0.30). Discordant results occurred more frequently among sera from Unvac-Ex (34.7%) followed by Vac-N (14.6%) and Vac-Ex (2.7%). Antibody levels quantified by both immunoassays were not significantly different when <250 (p = 0.87) or <1000 BAU/ml (p = 0.13); in contrast, for sera ≥1000 BAU/ml, the Roche assay returned significantly higher values than the DiaSorin assay (p < 0.008). Neutralizing antibody titers (NtAb) were measured in 127 sera from Vac-Ex or Vac-N using a S-pseudotyped virus neutralization assay of Wuhan-Hu-1, Omicron BA.1, and Omicron BA.2. The correlation between antibody levels and NtAb titers was higher for sera from Vac-N than those from Vac-Ex, irrespective of the (sub)variant considered. In conclusion, neither qualitative nor quantitative results returned by both immunoassays are interchangeable. The performance of both assays was found to be greatly influenced by the vaccination and SARS-CoV-2 infection status of individuals.

SARS-CoV-2 RNA load in nasopharyngeal specimens from outpatients with breakthrough COVID-19 due to Omicron BA.1 and BA.2.

This retrospective observational study compared severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA load in nasopharyngeal specimens (NPs) from patients with breakthrough coronavirus disease 2019 (COVID-19) caused by the Omicron BA.1 or BA.2 sublineages. The convenience sample was composed of 277 outpatients (176 female/112 male; median age, 48 years; range, 12-97) with breakthrough COVID-19 (n = 130 due to BA.1 and n = 147 due to BA.2). All participants had completed a full vaccination schedule and 56% had received a booster vaccine dose at the time of COVID-19 breakthrough microbiological diagnosis. NPs were collected within 7 days (median 2 days) after symptom onset. The TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific) was used to estimate viral loads in NPs. Overall, viral RNA loads in NPs were comparable (p = 0.31) for BA.1 (median, 7.1 log10 copies/ml; range, 2.7-10.6) and BA.2 (median, 7.5 log10 copies/ml; range, 2.7-10.6), yet peak viral load appeared to be reached sooner for BA.2 than for BA.1 (Day 1 vs. Days 3-5; p = 0.002). Time elapsed since last vaccine dose had no significant impact on SARS-CoV-2 RNA loads in the upper respiratory tract (URT) for either BA.1 or BA.2. The data presented do not support that the transmissibility advantage of BA.2 over BA.1 is related to generation of higher viral loads in the URT early after infection.

SARS-CoV-2 N-antigenemia in critically ill adult COVID-19 patients: Frequency and association with inflammatory and tissue-damage biomarkers.

The current study aimed at characterizing the dynamics of SARS-CoV-2 nucleocapsid (N) antigenemia in a cohort of critically ill adult COVID-19 patients and assessing its potential association with plasma levels of biomarkers of clinical severity and mortality. Seventy-three consecutive critically ill COVID-19 patients (median age, 65 years) were recruited. Serial plasma (n = 340) specimens were collected. A lateral flow immunochromatography assay and reverse-transcription polymerase chain reaction (RT-PCR) were used for SARS-CoV-2 N protein detection and RNA quantitation and in plasma, respectively. Serum levels of inflammatory and tissue-damage biomarkers in paired specimens were measured. SARS-CoV-RNA N-antigenemia and viral RNAemia were documented in 40.1% and 35.6% of patients, respectively at a median of 9 days since symptoms onset. The level of agreement between the qualitative results returned by the N-antigenemia assay and plasma RT-PCR was moderate (k = 0.57; p < 0.0001). A trend towards higher SARS-CoV-2 RNA loads was seen in plasma specimens testing positive for N-antigenemia assay than in those yielding negative results (p = 0.083). SARS-CoV-2 RNA load in tracheal aspirates was significantly higher (p < 0.001) in the presence of concomitant N-antigenemia than in its absence. Significantly higher serum levels of ferritin, lactose dehydrogenase, C-reactive protein, and D-dimer were quantified in paired plasma SARS-CoV-2 N-positive specimens than in those testing negative. Occurrence of SARS-CoV-2 N-antigenemia was not associated with increased mortality in univariate logistic regression analysis (odds ratio, 1.29; 95% confidence interval, 0.49-3.34; p = 0.59). In conclusion, SARS-CoV-2 N-antigenemia detection is relatively common in ICU patients and appears to associate with increased serum levels of inflammation and tissue-damage markers. Whether this virological parameter may behave as a biomarker of poor clinical outcome awaits further investigations.

T cell-mediated response to SARS-CoV-2 in liver transplant recipients with prior COVID-19.

Whether immunosuppression impairs severe acute respiratory syndrome coronavirus 2-specific T cell-mediated immunity (SARS-CoV-2-CMI) after liver transplantation (LT) remains unknown. We included 31 LT recipients in whom SARS-CoV-2-CMI was assessed by intracellular cytokine staining (ICS) and interferon (IFN)-γ FluoroSpot assay after a median of 103 days from COVID-19 diagnosis. Serum SARS-CoV-2 IgG antibodies were measured by ELISA. A control group of nontransplant immunocompetent patients were matched (1:1 ratio) by age and time from diagnosis. Post-transplant SARS-CoV-2-CMI was detected by ICS in 90.3% (28/31) of recipients, with higher proportions for IFN-γ-producing CD4+ than CD8+ responses (93.5% versus 83.9%). Positive spike-specific and nucleoprotein-specific responses were found by FluoroSpot in 86.7% (26/30) of recipients each, whereas membrane protein-specific response was present in 83.3% (25/30). An inverse correlation was observed between the number of spike-specific IFN-γ-producing SFUs and time from diagnosis (Spearman's rho: -0.418; p value = .024). Two recipients (6.5%) failed to mount either T cell-mediated or IgG responses. There were no significant differences between LT recipients and nontransplant patients in the magnitude of responses by FluoroSpot to any of the antigens. Most LT recipients mount detectable-but declining over time-SARS-CoV-2-CMI after a median of 3 months from COVID-19, with no meaningful differences with immunocompetent patients.

Performance of a MALDI-TOF mass spectrometry-based method for rapid detection of third-generation oxymino-cephalosporin-resistant Escherichia coli and Klebsiella spp. from blood cultures.

We optimized and prospectively evaluated a simple MALDI-TOF MS-based method for direct detection of third-generation oxymino-cephalosporin resistance (3rd CephR) in Escherichia coli and Klebsiella spp. from blood cultures (BC). In addition, we assessed the performance of a lateral flow immunochromatographic assay (LFIC) for detecting extended-spectrum ß-lactamases (ESBL) (NG-Test CTX-M MULTI assay) using bacterial pellets from BC. A total of 168 BCs from unique patients were included. A pre-established volume of BC flagged as positive was transferred in brain heart infusion with or without ceftriaxone (2 mg/ml). After 2-h incubation, intact bacterial pellets were used for MALDI-TOF MS testing. Identification of bacterial species (index score > 2) in the presence of CRO was considered marker of 3rd CephR. The LFIC assay was evaluated in 141 BC. Bacteremia episodes were caused by E. coli (n = 115) or Klebsiella spp. (n = 53). A total of 49 strains were 3rd CephR by broth microdilution, of which 41 were ESBL producers, seven expressed ESBL and OXA-48 type D carbapenemase, and one harbored a plasmid-mediated AmpC. The MALDI-TOF MS method yielded four very major errors (false susceptibility) and two major errors (false resistance). The overall sensitivity of the assay was 91.8% and the specificity 98.3%. Concordance between the LFIC assay and the MALDI-TOF MS method for detection of ESBL-mediated 3rd CephR was 100%. Both evaluated methods may prove useful for early adjustment of empirical therapy in patients with E. coli and Klebsiella spp. bloodstream infections. Whether their use has a beneficial impact on patient outcomes is currently under investigation.

Time to positivity of Coagulase Negative Staphylococcus In Neonatal Blood Cultures as an adjunct tool to help discriminate between sepsis and contamination.

OBJECTIVE: To assess the usefulness of time to positivity (TTP) to distinguish between sepsis and contamination in coagulase-negative staphylococci (CoNS) isolates. STUDY DESIGN: Unicentric retrospective observational. Medical records of 168 patients with suspected sepsis and positive blood culture for CoNS were reviewed. Patients were subdivided into sepsis (29%) and probable contamination (71%). Logistic regression analyses were performed to evaluate different risk factors and clinical signs and symptoms associated with sepsis. RESULTS: TTP cut-off value that best discriminated sepsis from contamination was found to be 18 h. Regression analysis revealed that TTP ≤ 18 h, gestational age ≤32 weeks, taquycardia/bradycardia and hypoactivity/lethargy were independent predictors of sepsis. CONCLUSION: TTP is useful in distinguishing sepsis from contamination, especially in neonates with lower gestational age (<32 weeks). The clinical signs that most increase the discriminatory power of TTP are the presence of tachycardia/bradycardia or hypoactivity.

Comparative performance of the Platelia Aspergillus Antigen and Aspergillus Galactomannan antigen Virclia Monotest immunoassays in serum and lower respiratory tract specimens: a "real-life" experience.

The Platelia Aspergillus Antigen immunoassay is the "gold standard" for Aspergillus galactomannan (GLM) measurement in sera and bronchoalveolar lavage (BAL) for the diagnosis of invasive pulmonary aspergillosis (IPA). We evaluated the performance of the Aspergillus GLM antigen Virclia Monotest compared to the Platelia assay. A total of 535 specimens [320 sera, 86 bronchial aspirates (BAs), 70 BAL, and 59 tracheal aspirates (TAs)] from 177 adult patients (72 hematological, 32 Intensive Care Unit, and 73 hospitalized in other wards) were processed for GLM testing upon clinical request. One patient had proven IPA, and 11 had probable disease. After excluding indeterminate Virclia results (n = 38), 396 specimens yielded concordant results (56 positive and 340 negative) and 101 discordant results (Virclia positive/Platelia negative, n = 95). The overall agreement between immunoassays was higher for sera (κ 0.56) than for BAL (κ ≤ 0.24) or BAS and TA (κ ≤ 0.22). When considering all specimen types in combination, the overall sensitivity and specificity of the Virclia assay for the diagnosis of proven/probable IPA were 100% and 65%, respectively, and for the Platelia immunoassay, sensitivity and specificity were 91.7% and 89.4%, respectively. The correlation between index values by both immunoassays was strong for serum/BAL (ρ = 0.73; P < 0.001) and moderate for BAS/TA (Rho = 0.52; P = 0.001). The conversion of Virclia index values into the Platelia index could be derived by the formula y = (11.97 * X)/3.62 + X). Data from GLM-positive serum/BAL clinical specimens fitted the regression model optimally (R2 = 0.94), whereas that of BAS and TA data did not (R2 = 0.11). Further studies are needed to determine whether the Virclia assay may be an alternative to the Platelia assay for GLM measurement in sera and lower respiratory tract specimens.IMPORTANCEGalactomannan detection in serum or bronchoalveolar fluid specimens is pivotal for the diagnosis of invasive pulmonary aspergillosis (IPA). The Platelia Aspergillus Antigen immunoassay has become the "gold standard" for Aspergillus GLM measurement. Here, we provide data suggesting that the Virclia Monotest assay, which displays several operational advantages compared with the Platelia assay, may become an alternative to the Platelia assay, although further studies are needed to validate this assumption. We also provide a formula allowing the conversion of Virclia index values into Platelia values. The study may contribute toward positioning the Virclia assay within the diagnostic algorithm of IPA.

Functional antibody responses targeting the Spike protein of SARS-CoV-2 Omicron XBB.1.5 in elderly nursing home residents following Wuhan-Hu-1-based mRNA booster vaccination.

The immune effector mechanisms involved in protecting against severe COVID-19 infection in elderly nursing home residents following vaccination or natural infection are not well understood. Here, we measured SARS-CoV-2 Spike (S)-directed functional antibody responses, including neutralizing antibodies (NtAb) and antibody Fc-mediated NK cell activity (degranulation and IFNγ production), against the Wuhan-Hu-1, BA.4/5 (for NtAb), and Omicron XBB.1.5 variants in elderly nursing home residents (n = 39; median age, 91 years) before and following a third (pre- and post-3D) and a fourth (pre- and post-4D) mRNA COVID-19 vaccine dose. Both 3D and 4D boosted NtAb levels against both (sub)variants. Likewise, 3D and 4D increased the ability of sera to trigger both LAMP1- and IFNγ-producing NK cells, in particular against XBB.1.5. In contrast to NtAb titres, the frequencies of LAMP1- and IFNγ-producing NK cells activated by antibodies binding to Wuhan-Hu-1 and Omicron XBB.1.5 S were comparable at all testing times. Stronger functional antibody responses were observed in vaccine-experienced participants compared to vaccine-naïve at some testing times. These findings can contribute to identifying a reliable correlate of protection in elderly nursing home residents against severe COVID-19 and inform future vaccine strategies in this population group.

RNA loads of severe acute respiratory syndrome coronavirus 2 in patients with breakthrough coronavirus disease 2019 caused by the Delta and Omicron variants.

OBJECTIVES: To compare the RNA loads of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal specimens collected from patients with breakthrough coronavirus disease 2019 (COVID-19) caused by the Delta variant with those in specimens collected from patients with breakthrough COVID-19 caused by the Omicron variant. METHODS: A retrospective, observational study was conducted, including 240 consecutive adult out-patients, of whom 121 (74 females; median age, 40 years) had COVID-19 due to the Omicron variant and 119 (65 females; median age, 48 years) had COVID-19 caused by the Delta variant. The viral RNA load was quantitated using the TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, Waltham, MS, USA). The viability platinum chloride reverse transcription-PCR assay was used to discriminate between potentially infectious viral particles and free (encapsidated) viral RNA. RESULTS: Overall, the viral RNA loads were significantly higher (p 0.003) for the Omicron variant (median, 8.1 log10 copies/mL; range, 4.0-10.9 log10 copies/mL) than for the Delta variant (median, 7.5 log10 copies/mL; range, 3.0-11.6 log10 copies/mL). A trend towards higher viral loads was noticed for Omicron compared with that for Delta across the following time frames since vaccination: 16-90 days (median, 6.83 vs. 5.88 log10 copies/mL, respectively; range, 3.91-10.68 vs. 3.67-9.66 log10 copies/mL, respectively; p 0.10), 91-180 days (median, 8.09 vs. 7.46 log10 copies/mL, respectively; range, 4.30-10.92 vs. 3.03-11.56 log10 copies/mL, respectively; p 0.003) and 181-330 days (median, 8.56 vs. 8.10 log10 copies/mL, respectively; range, 6.51-10.29 vs. 3.03-10.61 log10 copies/mL, respectively; p 0.11). The platinum chloride treated or untreated reverse transcription-PCR cycle threshold ratio for the nucleocapsid gene as the target was slightly higher for Omicron than for Delta (median, 0.62 vs. 0.57, respectively; range, 0.57-0.98 vs. 0.61-0.87, respectively), although statistical significance was not reached (p 0.10). CONCLUSION: The time elapsed since vaccination has a major impact on the RNA loads of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal specimens, particularly for the Omicron variant. The Omicron variant may be better adapted for replication in the upper respiratory tract than the Delta variant, in which this is unlikely given its more efficient generation of viral particles.

SARS-CoV-2-reactive IFN-γ-producing CD4+ and CD8+ T cells in blood do not correlate with clinical severity in unvaccinated critically ill COVID-19 patients.

We examined the relationship between peripheral blood levels of SARS-CoV-2 S (Spike protein)1/M (Membrane protein)-reactive IFN-γ-producing CD4+ and CD8+ T cells, serum levels of biomarkers of clinical severity, and mortality in critically ill COVID-19 patients. The potential association between SARS-CoV-2-S-Receptor Binding Domain (RBD)-specific IgG levels in sera and mortality was also investigated. SARS-CoV-2 T cells and anti-RBD IgG levels were monitored in 71 non-consecutive patients (49 male and 22 female; median age, 65 years) by whole-blood flow cytometry and Enzyme-linked immunosorbent assay (ELISA), respectively (326 specimens). SARS-CoV-2 RNA loads in paired tracheal aspirates [TA] (n = 147) were available from 54 patients. Serum levels of interleukin-6, ferritin, D-Dimer, lactose dehydrogenase and C-reactive protein in paired sera were known. SARS-CoV-2 T cells (either CD4+, CD8+ or both) were detectable in 70 patients. SARS-CoV-2 IFN-γ CD4+ T-cell responses were documented more frequently than their CD8+ counterparts (62 vs. 56 patients) and were of greater magnitude overall. Detectable SARS-CoV-2 S1/M-reactive CD8+ and CD4+ T-cell responses were associated with higher SARS-CoV-2 RNA loads in TA. SARS-CoV-2 RNA load in TA decreased over time, irrespective of the dynamics of SARS-CoV-2-reactive CD8+ and CD4+ T cells. No correlation was found between SARS-CoV-2 IFN-γ T-cell counts, anti-RBD IgG concentrations and biomarker serum levels (Rho ≤ 0.3). The kinetics of both T cell subsets was comparable between those who died or survived, whereas anti-RBD IgG levels were higher across different time points in deceased patients than in survivors. Enumeration of peripheral blood levels of SARS-CoV-2-S1/M-reactive IFN-γ CD4+ and CD8+ T cells does not predict viral clearance from the lower respiratory tract or poor clinical outcomes in critically ill COVID-19 patients. In contrast, anti-RBD IgG levels were directly associated with increased mortality.

Combined kinetic analysis of SARS-CoV-2 RNAemia, N-antigenemia and virus-specific antibodies in critically ill adult COVID-19 patients.

Combined kinetic analysis of plasma SARS-CoV-2 RNAemia, Nucleocapsid (N)-antigenemia and virus-specific antibodies may help ascertain the role of antibodies in preventing virus dissemination in COVID-19 patients. We performed this analysis in a cohort of 71 consecutive critically ill COVID-19 patients (49 male; median age, 65 years) using RT-PCR assay, lateral flow immunochromatography method and receptor binding domain (RBD) and N-based immunoassays. A total of 338 plasma specimens collected at a median of 12 days after symptoms onset were available for analyses. SARS-CoV-2 RNAemia and N-antigenemia were detected in 37 and 43 specimens from 26 (36.5%) and 30 (42.2%) patients, respectively. Free RNA was the main biological form of SARS-CoV-2 found in plasma. The detection rate for both viral components was associated with viral load at the upper respiratory tract. Median time to SARS-CoV-2-RBD antibody detection was 14 days (range, 4-38) from onset of symptoms. Decreasing antibody levels were observed in parallel to increasing levels of both RNAemia and N-antigenemia, yet overall a fairly modest inverse correlation (Rho = -0.35; P < 0.001) was seen between virus RNAemia and SARS-CoV-2-RBD antibody levels. The data cast doubts on a major involvement of antibodies in virus clearance from the bloodstream within the timeframe examined.

B- and T-cell immune responses elicited by the Comirnaty® COVID-19 vaccine in nursing-home residents.

OBJECTIVES: The immunogenicity of the Comirnaty® vaccine against coronavirus disease 2019 (COVID-19) has not been adequately studied in elderly people with comorbidities. We assessed antibody and T-cell responses targeted to the S protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) following full vaccination in nursing-home residents. METHODS: Sixty nursing-home residents (44 female, age 53-100 years), of whom ten had previously been diagnosed with COVID-19, and 18 healthy controls (15 female, age 27-54 years) were recruited. Pre- and post-vaccination blood specimens were available for quantification of total antibodies binding the SARS-CoV-2 S protein and for enumeration of SARS-CoV-2 S-reactive IFN-γ CD4+ and CD8+ T cells by flow cytometry. RESULTS: The seroconversion rate in (presumably) SARS-CoV-2-naïve nursing-home residents (41/43, 95.3%) was similar to that in controls (17/18, 94.4%). A booster effect was documented in post-vaccination samples of nursing-home residents with prior COVID-19. Plasma antibody levels were higher (p < 0.01) in recovered nursing-home residents (all 2500 IU/mL) than in individuals across the other two groups (median 1120 IU/mL in naïve nursing-home residents and 2211 IU/ml in controls). A large percentage of nursing-home residents had SARS-CoV-2 S-reactive IFN-γ CD8+ (naïve 31/49, 63.2%; recovered 8/10, 80%) or CD4+ T cells (naïve 35/49, 71.4%; recovered 7/10, 70%) at baseline, in contrast to healthy controls (3/17, 17.6% and 5/17, 29%, respectively). SARS-CoV-2 IFN-γ CD8+ and CD4+ T-cell responses were documented in 88% (15/17) and all control subjects after vaccination, respectively, but only in 65.5% (38/58) and 22.4% (13/58) of nursing-home residents. Overall, the median frequency of SARS-CoV-2 IFN-γ CD8+ and CD4+ T cells in nursing-home residents decreased in post-vaccination specimens, whereas it increased in controls. CONCLUSION: The Comirnaty COVID-19 vaccine elicits robust SARS-CoV-2 S antibody responses in nursing-home residents. Nevertheless, the rate and frequency of detectable SARS-CoV-2 IFN-γ T-cell responses after vaccination was lower in nursing-home residents than in controls.

Adaptive immune responses to SARS-CoV-2 in recovered severe COVID-19 patients.

BACKGROUND: There is an imperative need to determine the durability of adaptive immunity to SARS-CoV-2. We enumerated SARS-CoV-2-reactive CD4+ and CD8+ T cells targeting S1 and M proteins and measured RBD-specific serum IgG over a period of 2-6 months after symptoms onset in a cohort of subjects who had recovered from severe clinical forms of COVID-19. PATIENTS AND METHODS: We recruited 58 patients (38 males and 20 females; median age, 62.5 years), who had been hospitalized with bilateral pneumonia, 60% with one or more comorbidities. IgG antibodies binding to SARS-CoV-2 RBD were measured by ELISA. SARS-CoV-2-reactive CD69+-expressing-IFNγ-producing-CD4+ and CD8+ T cells were enumerated in heparinized whole blood by flow cytometry for ICS. RESULTS: Detectable SARS-CoV-2-S1/M-reactive CD69+-IFN-γ CD4+ and CD8+ T cells were displayed in 17 (29.3%) and 6 (10.3%) subjects respectively, at a median of 84 days after onset of symptoms (range, 58-191 days). Concurrent comorbidities increased the risk (OR, 3.15; 95% CI, 1.03-9.61; P = 0.04) of undetectable T-cell responses in models adjusted for age, sex and hospitalization ward. Twenty-one out of the 35 patients (60%) had detectable RBD-specific serum IgGs at a median of 118 days (range, 60-145 days) after symptoms onset. SARS-CoV-2 RBD-specific IgG serum levels were found to drop significantly over time. CONCLUSION: A relatively limited number of subjects who developed severe forms of COVID-19 had detectable SARS-CoV-2-S1/M IFNγ CD4+ and CD8+ T cells at midterm after clinical diagnosis. Our data also indicated that serum levels of RBD-specific IgGs decline over time, becoming undetectable in some patients.

SARS-CoV-2-specific Cell-mediated Immunity in Kidney Transplant Recipients Recovered From COVID-19.

BACKGROUND: The magnitude and kinetics of severe acute respiratory syndrome coronavirus 2-specific cell-mediated immunity (SARS-CoV-2-CMI) in kidney transplant (KT) recipients remain largely unknown. METHODS: We enumerated SARS-CoV-2-specific interferon-γ-producing CD69+ CD4+ and CD8+ T cells at months 4 and 6 from the diagnosis of coronavirus disease 2019 (COVID-19) in 21 KT recipients by intracellular cytokine staining. Overlapping peptides encompassing the SARS-CoV-2 spike (S) glycoprotein N-terminal 1- to 643-amino acid sequence and the membrane protein were used as stimulus. SARS-CoV-2 IgG antibodies targeting the S1 protein were assessed by ELISA at month 6. RESULTS: Detectable (≥0.1%) SARS-CoV-2-specific CD4+ T-cell response was found in 57.1% and 47.4% of patients at months 4 and 6. Corresponding rates for CD8+ T cells were 19.0% and 42.1%, respectively. Absolute SARS-CoV-2-specific T-cell counts increased from month 4 to month 6 in CD8+ (P = 0.086) but not CD4+ subsets (P = 0.349). Four of 10 patients with any detectable response at month 4 had lost SARS-CoV-2-CMI by month 6, whereas 5 of 9 patients mounted SARS-CoV-2-CMI within this period. All but 2 patients (89.5%) tested positive for SARS-CoV-2 IgG. Patients lacking detectable SARS-CoV-2-specific CD4+ response by month 6 were more likely to be under tacrolimus (100.0% versus 66.7%; P = 0.087) and to have received tocilizumab for the previous COVID-19 episode (40.0% versus 0.0%; P = 0.087). CONCLUSIONS: Although still exploratory and limited by small sample size, the present study suggests that a substantial proportion of KT recipients exhibited detectable SARS-CoV-2-CMI after 6 months from COVID-19 diagnosis.

Urgent Hospital Admissions Caused by Adverse Drug Reactions and Medication Errors-A Population-Based Study in Spain.

BACKGROUND: Adverse drug reactions (ADR) are a public health issue, due to their great impact on morbidity, mortality, and economic cost. OBJECTIVE: We aimed to study the percentage of patients admitted urgently as a result of an ADR, considered serious adverse event, or medication error. Also, we intended to identify possible risk factors which would lead to improvements in the prescription and use of medications. METHODS: This is a retrospective observational study conducted during February 2019, including patients admitted through the emergency department in our hospital. We evaluated the medical records of those with suspected ADR diagnoses to perform a descriptive analysis of the demographic characteristics. Moreover, after applying the Spanish Pharmacovigilance System causality algorithm, we performed a descriptive analysis of the identified ADR and the drugs involved. We also investigated those cases suspected of being a medication error. RESULTS: During the study period, 847 patients were urgently hospitalized. From those, 71 (29 women and 42 men) were admitted due to an ADR (8.4%, 95% CI 6.5%-10.3%). The mean age was 73 ± 15.9 years old and the mean number of prescribed medications was 7.3 ± 3.6 drugs/patient on admission. The most frequent ADR were opportunistic infections due to antineoplastic and immunomodulator drugs, and bleeding due to antiaggregants and anticoagulants. Five suspected medication errors occurred, being the incidence 0.6% (95% CI 0.08%-1.12%) of total admissions. CONCLUSIONS: 8.4% of urgent admissions were attributed to an ADR. Age (75% of patients were ≥ 65 years old), comorbidities and polymedication were the main risk factors. Although medication errors had a very low incidence (0.6% of urgent admissions), they were preventable and should be considered as a focus for action.