Healthy Healthcare Workers Research Articles

A longitudinal study of humoral immune responses induced by a 3-dose inactivated COVID-19 vaccine in an observational, prospective cohort

BackgroundTo determine the dynamic SARS-CoV-2 specific antibody levels induced by 3 doses of an inactivated COVID-19 vaccine, CoronaVac. An observational, prospective cohort study was performed with 93 healthy healthcare workers from a tertiary hospital in Nanjing, China. Serum SARS-CoV-2 specific IgM, IgG, and neutralizing antibodies (NAb) were measured at different time points among participants who received 3 doses of inactivated COVID-19 vaccine.Results91.3% (85/93) and 100% (72/72) participants showed positive both for SARS-CoV-2 specific IgG and NAb after 2-dose CoronaVac and after 3-dose CoronaVac, respectively. Anti-SARS-CoV-2 IgG responses reached 91.21 (55.66–152.06) AU/mL, and surrogate NAb was 47.60 (25.96–100.81) IU/mL on day 14 after the second dose. Anti-SARS-CoV-2 IgG responses reached 218.29 (167.53–292.16) AU/mL and surrogate NAb was 445.54 (171.54–810.90) IU/mL on day 14 after the third dose. Additionally, SARS-CoV-2 specific surrogate neutralizing antibody titers were highly correlated with serum neutralization activities against Ancestral, Omicron, and Delta strains. Moreover, significantly higher SARS-CoV-2 IgG responses, but not NAb responses, were found in individuals with breakthrough infection when compared to that of 3-dose CoronaVac recipients.ConclusionsCoronaVac elicited robust SARS-CoV-2 specific humoral responses. Surrogate NAb assay might substitute for pseudovirus neutralization assay. Monitoring SARS-CoV-2 antibody responses induced by vaccination would provide important guidance for the optimization of COVID-19 vaccines.

Evaluation of five immunoassays and one lateral flow immunochromatography for anti-SARS-CoV-2 antibodies detection

IntroductionIn order to deal with the current pandemic caused by the novel SARS-CoV-2 coronavirus several serological immunoassays have been recently developed with the objective of being used as a complementary diagnostic tool and to support the RT-PCR technique currently considered the “gold-standard” method. However, these new assays need to be evaluated and validated. The purpose of this study was to assess the performance of five immunoassays (two ELISA and three CLIA assays) and one rapid immunochromatographic test for the detection of anti-SARS-CoV-2 antibodies. MethodsFive semiquantitative immunoassays (MENARINI®, PALEX®, VIRCLIA®, ROCHE® and SIEMENS®) and one lateral flow rapid test (WONDFO®) were performed. A total of 124 samples were studied. Case serum samples (n=78) were obtained from COVID-19 patients confirmed by real-time RT-PCR/epidemiological-clinical-radiological criteria, and control non-SARS-CoV-2 samples (n=46) belonged to healthy healthcare workers involved in a seroprevalence study. ResultsOverall, the tests showed sensitivities around 70–90% and specificities greater than 95%, including the immunochromatographic test. In addition, we observed very good agreements among them, being better for the detection of IgG than for IgM antibodies (Cohen's kappa index of 0.95 for VIRCLIA® IgG with ROCHE®), as well as good diagnostic power of the tests as determined by the ROC curves. ConclusionsThis study demonstrates the proper performance of the different immunoassays in order to be applied in the clinical practice as support in the diagnostic approach and in the development of vaccines and seroepidemiological studies of COVID-19.

A prospective study on myocardial injury after BNT162b2 mRNA COVID-19 fourth dose vaccination in healthy persons.

AimsTo prospectively evaluate the incidence of myocardial injury after the administration of the fourth dose BNT162b2 mRNA vaccine (Pfizer‐BioNTech) against COVID‐19.Methods and resultsHealth care workers who received the BNT162b2 vaccine during the fourth dose campaign had blood samples collected for high‐sensitivity cardiac troponin (hs‐cTn) during vaccine administration and 2–4 days afterward. Vaccine‐related myocardial injury was defined as hs‐cTn elevation above the 99th percentile upper reference limit and >50% increase from baseline measurement. Participants with evidence of myocardial injury underwent assessment for possible myocarditis. Of 324 participants, 192 (59.2%) were female and the mean age was 51.8 ± 15.0 years. Twenty‐one (6.5%) participants had prior COVID‐19 infection, the mean number of prior vaccine doses was 2.9 ± 0.4, and the median time from the last dose was 147 (142–157) days. Reported vaccine‐related adverse reactions included local pain at injection site in 57 (17.59%), fatigue in 39 (12.04%), myalgia in 32 (9.88%), sore throat in 21 (6.48%), headache in 18 (5.5%), fever ≥38°C in 16 (4.94%), chest pain in 12 (3.7%), palpitations in 7 (2.16%), and shortness of breath in one (0.3%) participant. Vaccine‐related myocardial injury was demonstrated in two (0.62%) participants, one had mild symptoms and one was asymptomatic; both had a normal electrocardiogram and echocardiography.ConclusionIn a prospective investigation, an increase in serum troponin levels was documented among 0.62% of healthy health care workers receiving the fourth dose BNT162b2 vaccine. The two cases had mild or no symptoms and no clinical sequela.Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT05308680.

Use of Personal Protective Equipment Among Healthcare Workers During the First and the Second Wave of the COVID-19 Pandemic.

IntroductionTo treat and properly care for COVID-19 patients it is vital to have healthy healthcare workers to ensure the continued function of the healthcare system and to prevent transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to patients, co-workers, and the community. Personal protective equipment (PPE) can prevent healthcare workers from being infected with and transmitting SARS-CoV-2. Experience and training are pivotal to ensure optimal protection. This study aims to examine the use and failure of PPE and compliance with PPE guidelines during the first and the second wave of the COVID-19 pandemic among Danish healthcare workers.MethodsHealthcare workers from the Central Denmark Region and the Capital Region of Denmark were invited to participate April–June 2020 during the first wave and November 2020–April 2021 during the second wave. Day-by-day, participants reported work procedures, use and failure of PPE, and compliance with PPE guidelines. Register-based information on sex, age, department, and profession was available for all participants.ResultsIn total, 21 684 and 10 097 healthcare workers participated during the first and the second wave, respectively. During the first wave, 1.7% used filtering face piece-2 or -3 (FFP2 or FFP3) respirators and 8.2% used face masks [fluid resistant (type IIR) masks, masks with visor (typically type IIR), and other unspecified face masks] during physical contact with patients. During the second wave, the corresponding figures increased to 17.8% and 80.7%. During respiratory procedures, the use of FFP2 or FFP3 respirators increased from 5.6 to 24.3%, and the use of face masks from 14.7 to 77.8%. The no PPE use decreased from 21.3% during the first wave to 0.4% in the second wave, during respiratory procedures. Total PPE failures decreased from 0.7 to 0.4% from the first to second wave. The proportion not complying with PPE guidelines declined from 3.6 to 2.2% during physical contact with patients and from 6.5 to 4.6% during respiratory procedures. PPE failure and non-compliance varied by age, sex and type of department. Frequent reasons for non-compliance were forgetfulness and lack of time, and during the first but not during the second wave, limited availability of PPE.ConclusionWe found a substantial increase in the use of PPE and a substantial decrease in PPE failures from the first to the second wave of COVID-19 in Denmark. However, there is still a need for continuous focus on compliance in use of PPE among healthcare workers.

Mean Six Minute Walk Distance of Healthy Healthcare Workers of a Tertiary Care Centre: A Descriptive Cross-sectional Study.

The six-minute walk test is a sub-maximal exercise test used in clinical populations to determine functional exercise capacity. It is a safe, simple, and inexpensive test. There are a number of reference equations described for estimating six-minute walk distance in healthy subjects in different countries. However, there is a lack of standard reference value for six minute walk distance in healthy Nepalese population. The aim of the study was to find the mean six minute walk distance of healthy healthcare workers of a tertiary care centre. A descriptive cross-sectional study was conducted among healthy health care workers of a tertiary care centre from 1 August 2021 to 30 November 2021 after taking ethical approval from Institutional Review Committee (Reference number: 1507202105). Convenience sampling was done. Point estimate and 95% Confidence Interval were calculated. The mean six-minute walk distance of the 162 healthy health care workers was 486.74±74.73 (475.23-498.24, 95% Confidence Interval) m. Men walked 519.61±79.19 m and women walked 474.12±75.62 m. The mean age of the participants was 29.25±8.25 years. The mean six-minute walk distance was found to be lower when compared to similar studies conducted in similar settings. exercise test; health personnel; healthy volunteer; walk test.

Long Term Cell Immune Response to COVID-19 Vaccines Assessment Using a Delayed-Type Hypersensitivity (DTH) Cutaneous Test.

Objective: As we progress with mass vaccination against SARS-CoV-2, there are key questions about the immunogenicity of COVID-19 vaccines that still are not answered. Conventional methods to measure cellular immune responses are complex and expensive in a pandemic situation. Patients and methods: Forty healthy healthcare workers accepted to participate during the vaccination schedule with a mRNA vaccine against SARS-CoV-2. Measurement of Delayed-Type Hypersensitivity (DTH) cutaneous response after intradermal test of protein S of SARS-CoV-2 at day 35 and day 200 was performed. At the same time, a specific anti-RBD IgG using a classic ELISA before vaccination, and on days 0, 35, and 200 was performed. Results: All 40 individuals had a positive DTH skin response at day 35, whereas 39 participants had a positive skin test at day 200. Moreover, although all 40 individuals showed a positive humoral response of specific IgG against spike protein at day 35, with most of them having significantly lower levels at day 200. Conclusion: DTH could be proposed as an ideal and easy method to predict cellular immunity response to mRNA vaccines 200 days after starting an immunization schedule with mRNA vaccine for COVID-19.

SARS-CoV-2 antibody response after BNT162b2 mRNA vaccine in healthcare workers: Nine-month of follow-up

We collected sequential serum samples (0, 4, 12 weeks, 9 months) for the determination of S-RDB IgG levels from 103 vaccinated healthy subjects (age 45 ± 13 years; 60 women), in order to evaluate neutralizing antibody response against SARS-CoV-2 in healthy healthcare workers (HCWs) after the administration of two doses of BNT162b2 SARS-CoV-2 mRNA vaccine. Every subject received two doses of mRNA vaccine BNT162b2 (Pfizer-BioNTech), 21 days apart (January-February 2021). Furthermore, antibody titer of 14 subjects who were hospitalized for symptomatic COVID-19 was evaluated. Antibody response was (median, interquartile range) 35 U/mL (10–104) at baseline, 1960 (1241–3221) at 4 weeks, 791 (388–1179) at 12 weeks and 524 (273–931) at 6 months. Antibody response was inversely correlated with age at all timepoints (p < 0.001) while gender and Body Mass Index had no significant effect. At multivariate analysis, post-baseline values were significantly higher than baseline (p < 0.001) with a reduction at 12 weeks and 9 months (p < 0.001). Antibody response of hospitalized subjects who did not receive vaccination, symptomatic for COVID 19 infection, was 103 (25–557) U/mL, significantly higher than baseline (p = 0.007) of study population but lower than all post-baseline determinations (p < 0.001). Younger subjects showed a stronger response and a lower decrease of antibody titers compared to the classes of older subjects. SARS-CoV2 infection was excluded by performing 1017 nasopharyngeal RT-PCR swabs on the study cohort. The second dose of mRNA vaccine resulted in an antibody response effective in preventing infection in a population of healthcare professionals. The antibody level was stable through week 12, showing a reduction in the following six months.

Point-of-care lung ultrasonography for early identification of mild COVID-19: a prospective cohort of outpatients in a Swiss screening center

ObjectivesEarly identification of SARS-CoV-2 infection is important to guide quarantine and reduce transmission. This study evaluates the diagnostic performance of lung ultrasound (LUS), an affordable, consumable-free point-of-care tool, for COVID-19...

MO919: Persistence of Antibodies After SARS-COV-2 Vaccines in Haemodialysis Patients: A 6 Months Follow-Up

BACKGROUND AND AIMSAs COVID-19 related mortality is higher in haemodialysis patients than in the general population, proper vaccination strategies against the SARS-CoV-2 virus have utmost importance. It has been previously shown that mRNA vaccines (e.g. BNT162b2) can generate >95% of seropositivity in haemodialysis patients [1]. On the other hand, the seropositivity rate reached by the inactivated vaccine (CoronaVac®) was around 80%. In this study, we aimed to analyse the persistence of SARS-CoV-2 antibodies in haemodialysis patients for 6 months and compare it with the healthy controls.METHODHaemodialysis patients who were vaccinated either by BNT162b2 or CoronaVac® and who continued their regular controls for 6 months were involved in the study. Those who had previous or active SARS-CoV-2 infection, who had malignancies and those who had received immunosuppressive drugs in the previous 12 month were excluded from the study. SARS-CoV-2 IgG levels were measured by a commercial test after the first doses of the vaccines and at the end of the sixth month. Healthy healthcare workers who were vaccinated with similar vaccine schemes were taken as the control group.RESULTSWe recruited 85 haemodialysis patients who had received their first doses of either vaccine. Of them, 4 patients died; 3 patients were hospitalized because of COVID-19 infection during the follow-up; 9 patients missed at least one of their regular controls; and 2 patients were diagnosed with malignancy. A total of 26 patients experienced asymptomatic or mild COVID-19 infection during the follow-up period. SARS-CoV-2 IgG levels were measured at the end of the sixth month for the remaining 41 patients. Sero-positivity significantly decreased at the end of the sixth month for both vaccines, but the BNT162b2 group (n = 22) still had better seropositivity than CoronaVac® (n = 19) group (81% versus 50%; P = .03). In contrast, the seropositivity of healthy controls, even with the inactivated vaccine, was 96%. When one booster dose was applied, 90% of seropositivity could be maintained in the BNT162b2 group at the sixth month.CONCLUSIONBNT162b2 vaccine generates more persistent antibodies than inactivated vaccines in haemodialysis patients. However, when compared with the healthy controls at the end of the sixth month, antibody titers decrease more profoundly in haemodialysis patients. The booster dose can maintain the antibody levels and should be applied at least every 6 months.

Severe acute respiratory syndrome coronavirus 2 vaccination induces short-term polyclonal antibody response against seasonal endemic coronaviruses

Abstract Antibody (Ab) responses induced by endemic human coronaviruses (HCoVs) may affect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific Ab production due to cross-reactivity among these HCoVs. To explore this hypothesis, we collected serum samples of healthy healthcare workers (HCW) at four time-points: pre-vaccination, post-vaccination (1st and 2nd dose) and 6 months post-vaccination. We used N protein peptide-based enzyme-linked immunosorbent assays (ELISA) specific for alphaCoVs (NL63 and 229E) and betaCoVs (OC43 and HKU1) as well as N and S peptide-based ELISA for SARS-CoV-2. Low levels of SARS-CoV-2 N protein-specific Abs were present in some individuals prior to vaccination. The level remained constant following one or two doses of vaccine and declined after 6 months. SARS-CoV-2 S protein-specific Abs level were low in most individuals prior to vaccination, increased sharply following 1st and 2nd vaccinations and declined by 6 months. We observed low levels of pre-existing IgG Abs against endemic HCoVs prior to COVID-19 vaccination. However, like SARS-CoV-2-specific IgG Ab titers, they increased (1.6–1.9-fold) following SARS-CoV-2 vaccination and waned 6 months later. IgG Abs surge targeting HCoV N protein suggest polyclonal activation of memory B cell responses induced by the S gene based COVID-19 vaccines. The levels of IgG Abs against endemic HCoVs were 1.1–1.5 times higher in SARS-CoV-2 seropositive vs. seronegative individuals, suggesting serological cross-reactivity between SARS-CoV-2 and other HCoVs. In summary, short-term immunity (six months) against common cold causing HCoVs can be reactivated following COVID-19 vaccination however it requires booster dose for long term protection.

SARS-CoV-2 vaccine humoral response in adults with Down syndrome

ObjectivePeople with Down syndrome (DS) are particularly vulnerable to coronavirus disease 2019 (COVID-19) and show altered immune response to vaccination. We aimed to evaluate the immune response of a group of adults with DS treated with standard regimens of SARS-CoV-2 vaccine as compared with an age- and sex-matched group of persons without DS. MethodsWe compared antibody responses between 42 subjects with DS (41.6 ± 10.8 years, 57% male), and an age- and sex-matched comparison group of healthy health care workers (HCW) (41.4 ± 8.8 years, 54.8% male) after SARS-CoV-2 vaccination with the standard regimen of BNT162b2 mRNA COVID-19. Receptor binding domain (RBD) IgG antibodies were assessed at 4 time points (baseline, 21 days after the first dose, 21 days after the second dose, and 6 months after the first dose) with Siemens SARS-CoV-2 IgG (COV2G) antibody test. ResultsWe observed significantly different antibody responses at all time points after vaccination (HCW vs. DS: 7.9 ± 3.9 vs. 1.4 ± 3.6 IU/mL at 21 days after first dose; 358.5 ± 3.8 vs. 38.1 ± 3.0 IU/mL at 21 days after second dose; 34.6 ± 2.4 vs. 7.9 ± 3.1 IU/mL at 6 months after vaccination) and a significantly different time course of decline in antibody titers between the two groups. DiscussionSubjects with DS have a valid antibody response to SARS-CoV-2 vaccination. However, this response is lower than that of subjects in the HCW group. This finding could indicate a more rapid decline in the protective effects of the vaccination in subjects with DS and could suggest that people with DS may benefit from a booster dose of vaccine.

Assessment of the impact of N95 respirators or surgical masks use on the retinal microvasculature.

To determine the possible impact of wearing N95 respirator or surgical masks on retinal vessel diameters and choroidal thickness in healthy healthcare workers. Diameters of peripapillary retinal arteries and veins and choroidal thickness values at the foveal center and at 1000 μm distances from the foveal center in both nasal and temporal directions were measured before mask wearing using a spectral-domain optical coherence tomography. After four hours (h) of N95 or surgical mask wearing vessel diameter and choroidal thickness measurements were repeated. A total of 52 eyes from 52 participants (28 F [53.8%]; 24 M [46.2%]) were enrolled in this study. The mean age of patients was 34.58 ± 5.24 years (25-44 years). The diameters of all measured arteries [inferior temporal artery (p = 0.003), superior temporal artery (p < 0.001), inferior nasal artery (p = 0.003), and superior nasal artery (p = 0.004)] and veins,with the exception of superior nasal vein, (inferior temporal vein (p = 0.031), superior temporal vein (p = 0.027), inferior nasal vein (p < 0.001), and superior nasal vein (p = 0.063)] increased significantly after four hour use of N95 respirators and surgical maskswhen compared to baseline. There was also a significant diameter increase of the superior temporal (p < 0.001), inferior nasal veins (p < 0.001), and superior temporal artery (p = 0.037) for N95 respirators and surgical masks use, respectively. The differences in central subfoveal, temporal, and nasal choroidal thickness between baseline and after 4 h use of N95 respirators were statistically significant (From 366.73 ± 70.81 μm to 381.23 ± 69.29μm,p < 0.001 for the subfoveal; from 324.00 ± 64.13μm to 335.40 ± 61.35 μm, p = 0.007 for the temporal; from 297.40 ± 68.18 μm to 308.23 ± 74.51μm, p = 0.002 for the nasal thicknesses). Choroidal thickness values were also increased with surgical mask use. But only the increase in central subfoveal thickness was statistically significant (From 366.78 ± 71.00 μm to 372.58 ± 76.56 μm, p = 0.031 for the central subfoveal; from 297.42 ± 68.35 μmto 302.79 ± 73.05 μm, p = 0.068 for the nasal; from 324.01 ± 64.21μm to 330.33 ± 65.84, p = 0.117 for the temporal thicknesses). With four hours use of N95 respirators or surgical face masks, retinal vessel diameters and choroidal thicknesses showed an increase in comparison to baseline measurements. Hemodynamic changes seen secondary to hypercapnia due to prolonged use of N95 respirators or surgical masks may also be observed in the retinal and choroidal circulation. Furthermore, the use of face masks should be taken into account while assessing the retinal microvasculature.

Vaccination for SARS-CoV-2 in Patients With Psoriatic Arthritis: Can Therapy Affect the Immunological Response?

BackgroundA few studies on vaccination in patients with rheumatic diseases, including arthritis, connective tissue diseases, vasculitis, and psoriatic arthropathy (PsA), demonstrated reduced production of neutralizing antibodies to SARS-CoV-2 Spike RBD (receptor-binding domain contained in the N-terminal of the S1 globular head region) when compared to the general population.ObjectiveThe aim of our study was to observe whether different therapies for PsA [methotrexate, anti-TNF antibodies, soluble TNF receptor (etanercept) or IL-17 inhibitors] have a different impact on SARS-CoV-2 vaccination in a homogeneous population of patients.MethodsWe enrolled 110 PsA patients in remission, assessed with Disease Activity in PSoriatic Arthritis (DAPSA). Of these: 63 were in treatment with anti-TNF-α therapy (26 etanercept, 15 certolizumab, 5 golimumab, 17 adalimumab); 37 with anti-IL17 secukinumab; 10 with methotrexate. All patients underwent vaccination for SARS-CoV-2 with mRNA BNT162b2 vaccine. Assessment of absolute and percentage lymphocyte subsets and anti-SARS-CoV-2 Spike RBD IgG antibody value 3 weeks after the second vaccine dose were performed. In addition, the serum antibody levels of 96 healthy healthcare workers (HCW) were analyzed.ResultsThe mean disease activity assessed with DAPSA score was 2.96 (SD = 0.60) with no significant differences between patients under different medications (p = 0.779). Median levels of neutralizing antibodies to SARS-CoV-2 Spike RBD were 928.00 binding antibody unit (BAU)/mL [IQR 329.25, 1632.0]; 1068.00 BAU/ml [IQR 475.00, 1632.00] in patients taking MTX, 846.00 BAU/ml [IQR 125.00, 1632.00] in patients taking etanercept, 908.00 BAU/mL [IQR 396.00, 1632.00] in patients taking anti-IL17 and 1148.00 BAU/ml [IQR 327.00, 1632.00] in patients taking TNF-α inhibitors, without statistically significant differences between these groups. Mean serum antibody level of HCW group was 1562.00 BAU/ml [IQR 975.00, 1632.00], being significantly higher than in the patient group (p = 0.000816). Absolute and percentage count of lymphocyte subsets were not statistically different between the subgroups under different treatments and when compared with HCW.ConclusionsAs for other rheumatic diseases on immunomodulatory treatment, our data showed a reduced humoral response in PsA patients compared to the control group. However, antibody response did not significantly differ between groups treated with different medications.

The Cardiopulmonary Effects of Medical Masks and Filtering Facepiece Respirators on Healthy Health Care Workers in the Emergency Department: A Prospective Cohort Study

BackgroundInternational COVID-19 guidelines recommend that health care workers (HCWs) wear filtering facepiece (FFP) respirators to reduce exposure risk. However, there are concerns about FFP respirators causing hypercapnia via rebreathing carbon dioxide (CO2). Most previous studies measured the physiological effects of FFP respirators on treadmills or while resting, and such measurements may not reflect the physiological changes of HCWs working in the emergency department (ED). ObjectiveOur aim was to evaluate the physiological and clinical impacts of FFP type II (FFP2) respirators on HCWs during 2 h of their day shift in the ED. MethodsWe included emergency HCWs in this prospective cohort study. We measured end-tidal CO2 (ETCO2), mean arterial pressure (MAP), respiratory rate (RR), and heart rate values and dyspnea scores of subjects at two time points. The first measurements were carried out with medical masks while resting. Subjects then began their day shift in the ED with medical mask plus FFP2 respirator. We called subjects after 2 h for the second measurement. ResultsThe median age of 153 healthy volunteers was 24.0 years (interquartile range 24.0–25.0 years). Subjects’ MAP, RR, and ETCO2 values and dyspnea scores were significantly higher after 2 h. Median ETCO2 values increased from 36.4 to 38.8 mm Hg. None of the subjects had hypercapnia symptoms, hypoxia, or other adverse effects. ConclusionWe did not observe any clinical reflection of these changes in physiological values. Thus, we evaluated these changes to be clinically insignificant. We found that it is safe for healthy HCWs to wear medical masks plus FFP2 respirators during a 2-h working shift in the ED.

Antibody Response Induced by Two Doses of ChAdOx1 nCoV-19, mRNA-1273, or BNT162b2 in Liver Transplant Recipients.

Coronavirus disease 2019 (COVID-19) vaccination in immunocompromised, especially transplant recipients, may induce a weaker immune response. But there are limited data on the immune response after COVID-19 vaccination in liver transplant (LT) recipients, especially on the comparison of Ab responses after different vaccine platforms between mRNA and adenoviral vector vaccines. Thus, we conducted a prospective study on LT recipients who received two doses of the ChAdOx1 nCoV-19 (ChAdOx1), mRNA-1273, or BNT162b2 vaccines compared with healthy healthcare workers (HCWs). SARS-CoV-2 S1-specific IgG Ab titers were measured using ELISA. Overall, 89 LT recipients (ChAdOx1, n=16 [18%]) or mRNA vaccines (mRNA-1273 vaccine, n=23 [26%]; BNT162b2 vaccine, n=50 [56%]) received 3 different vaccines. Of them, 16 (18%) had a positive Ab response after one dose of COVID-19 vaccine and 62 (73%) after 2 doses. However, the median Ab titer after two doses of mRNA vaccines was significantly higher (44.6 IU/ml) than after two doses of ChAdOx1 (19.2 IU/ml, p=0.04). The longer time interval from transplantation was significantly associated with high Ab titers after two doses of vaccine (p=0.003). However, mycophenolic acid use was not associated with Ab titers (p=0.53). In conclusion, about 3-quarters of LT recipients had a positive Ab response after 2 doses of vaccine, and the mRNA vaccines induced higher Ab responses than the ChAdOx1 vaccine.

Prevalence of Malaria in Apparently Healthy Healthcare Workers in Dass Local Government Area, Bauchi State, Nigeria

Background: Malaria is among the world’s life-threatening protozoan diseases, especially in the tropics with increasing morbidity and mortality at an unprecedented high level. Healthcare workers (HCWs) in the tropics are increasingly affected despite the availability of effective preventive interventions. The study determines the prevalence of malarial parasitaemia in apparently healthy HCWs in Dass Local Government Area of Bauchi State. Methods: A schedule was used to collect information from 223 HCWs using a cross-sectional study design. The respondents were selected through multistage sampling. Blood sample from each participant was collected for malaria diagnosis using both Microscopy and Rapid Diagnostic Test (P. falciparum histidine-rich protein-2, HRP-2 mRDT). Results: The prevalence of malaria was 55.2 % using Microscopy (HRP-2 mRDT- 40.4 %). The RDT kit has a sensitivity of 66.7 %, specificity of 92.0 %, positive predictive value (PPV) of 91.1 % and a negative predictive value (NPV) of 69.2 %. The majority of the positive cases (91.9 %) had low parasitaemia (&lt; 1,000 parasites per µL of blood ) and 8.1 % had moderate parasitaemia (1,000 - 9,999 parasites per µL of blood). A significant association (χ² = 78. 868, df = 1, p &lt; 0.001, phi = 0.595) exists between RDT and Microscopy with a large effect size. No significant association between asymptomatic parasitaemia and insecticide-treated nets (ITNs) utilization (p ≥ 0.05). Conclusions: The prevalence of asymptomatic malarial parasitaemia was high despite the use of ITNs suggesting workplace hazard-related exposure. In addition to ITNs use, proper environmental sanitation (ensuring proper drainage systems), use of long-sleeved stockings, mosquito repellents and mosquito sprays should be encouraged in health facilities.

Prevalence of Malaria in Apparently Healthy Healthcare Workers in Dass Local Government Area, Bauchi State, Nigeria

Background: Malaria is among the world’s life-threatening protozoan diseases, especially in the tropics with increasing morbidity and mortality at an unprecedented high level. Healthcare workers (HCWs) in the tropics are increasingly affected despite the availability of effective preventive interventions. The study determines the prevalence of malarial parasitaemia in apparently healthy HCWs in Dass Local Government Area of Bauchi State. Methods: A schedule was used to collect information from 223 HCWs using a cross-sectional study design. The respondents were selected through multistage sampling. Blood sample from each participant was collected for malaria diagnosis using both Microscopy and Rapid Diagnostic Test (P. falciparum histidine-rich protein-2, HRP-2 mRDT). Results: The prevalence of malaria was 55.2 % using Microscopy (HRP-2 mRDT- 40.4 %). The RDT kit has a sensitivity of 66.7 %, specificity of 92.0 %, positive predictive value (PPV) of 91.1 % and a negative predictive value (NPV) of 69.2 %. The majority of the positive cases (91.9 %) had low parasitaemia (&lt; 1,000 parasites per µL of blood ) and 8.1 % had moderate parasitaemia (1,000 - 9,999 parasites per µL of blood). A significant association (χ² = 78. 868, df = 1, p &lt; 0.001, phi = 0.595) exists between RDT and Microscopy with a large effect size. No significant association between asymptomatic parasitaemia and insecticide-treated nets (ITNs) utilization (p ≥ 0.05). Conclusions: The prevalence of asymptomatic malarial parasitaemia was high despite the use of ITNs suggesting workplace hazard-related exposure. In addition to ITNs use, proper environmental sanitation (ensuring proper drainage systems), use of long-sleeved stockings, mosquito repellents and mosquito sprays should be encouraged in health facilities.

Evaluation of antibody response to BNT162b2 mRNA COVID-19 vaccine in patients affected by immune-mediated inflammatory diseases up to 5 months after vaccination

SARS-CoV-2 vaccination with mRNA product BNT162b2 elicited high immunogenicity in healthy subjects in trials. This study aims to better understand the factors that influence the humoral immune response to vaccination against SARS-CoV-2 in patients with immune-mediated inflammatory diseases (IMIDs). We enrolled patients and healthy healthcare workers control group (HCW) that underwent mRNA BNT162b2 vaccination and measured the serum IgG anti-S-RBD response at booster dose (T1), one month after booster dose (T2) and up to 5 months (T3). Demographic, disease-specific and vaccination data were recorded. Vaccination response of 551 participants naïve to SARS-CoV-2 infection were included in HCW and 102 in the IMID group, analyzing separately those on anti-CD20. At T2 all naïve HCW developed anti-S-RBD-IgG, while 94% of IMID responded (p < 0.001). IMID patients had a significantly different level of IgG than HCW at both T1 (p = 0.031), T2 (p < 0.001), while there was no significant difference at T3. There were no statistically significant differences according to the IMID type or to ongoing treatment with immunosuppressants, corticosteroids or biological drugs other than anti-CD20. The proportion and magnitude of response was significantly lower in IMID treated with anti-CD20 drugs. There was a correlation with age at T1 and at T2 but not at T3, stronger in patients than in HCW. Immune response close after BNT162b2 vaccination is reduced in patients with IMID, but there is no significant difference at 5 months. The measured reduction is related to age and the disease itself rather than treatments, with the exception of anti-CD20 drugs.

BNT162b2 SARS-CoV-2 Vaccination Elicits High Titers of Neutralizing Antibodies to Both B.1 and P.1 Variants in Previously Infected and Uninfected Subjects

We aimed to investigate neutralizing antibody titers (NtAbT) to the P.1 and B.1 SARS-CoV-2 variants in a cohort of healthy health care workers (HCW), including 20 previously infected individuals tested at baseline (BLinf, after a median of 298 days from diagnosis) and 21 days after receiving one vaccine dose (D1inf) and 15 uninfected subjects tested 21 days after the second-dose vaccination (D2uninf). All the subjects received BNT162b2 vaccination. D1inf NtAbT increased significantly with respect to BLinf against both B.1 and P.1 variants, with a fold-change significantly higher for P.1. D1inf NtAbT were significantly higher than D2uninf NtAbT, against B.1 and P.1. NtAbT against the two strains were highly correlated. P.1 NtAbT were significantly higher than B.1 NtAbT. This difference was significant for post-vaccination sera in infected and uninfected subjects. A single-dose BNT162b2 vaccination substantially boosted the NtAb response to both variants in the previously infected subjects. NtAb titers to B.1 and P.1 lineages were highly correlated, suggesting substantial cross-neutralization. Higher titers to the P.1 than to the B.1 strain were driven by the post-vaccination titers, highlighting that cross-neutralization can be enhanced by vaccination.

Optimization and Standardization of Human Saliva Collection for MALDI-TOF MS.

SARS-CoV-2 outbreak led to unprecedented innovative scientific research to preclude the virus dissemination and limit its impact on life expectancy. Waiting for the collective immunity by vaccination, mass-testing, and isolation of positive cases remain essential. The development of a diagnosis method requiring a simple and non-invasive sampling with a quick and low-cost approach is on demand. We hypothesized that the combination of saliva specimens with MALDI-TOF MS profiling analyses could be the winning duo. Before characterizing MS saliva signatures associated with SARS-CoV-2 infection, optimization and standardization of sample collection, preparation and storage up to MS analyses appeared compulsory. In this view, successive experiments were performed on saliva from healthy healthcare workers. Specimen sampling with a roll cotton of Salivette® devices appeared the most appropriate collection mode. Saliva protein precipitation with organic buffers did not improved MS spectra profiles compared to a direct loading of samples mixed with acetonitrile/formic acid buffer onto MS plate. The assessment of sample storage conditions and duration revealed that saliva should be stored on ice until MS analysis, which should occur on the day of sampling. Kinetic collection of saliva highlighted reproducibility of saliva MS profiles over four successive days and also at two-week intervals. The intra-individual stability of saliva MS profiles should be a key factor in the future investigation for biomarkers associated with SARS-CoV-2 infection. However, the singularity of MS profiles between individuals will require the development of sophisticated bio-statistical analyses such as machine learning approaches. MALDI-TOF MS profiling of saliva could be a promising PCR-free tool for SARS-CoV-2 screening.