SARS-CoV-2 infection triggers more potent antibody-dependent cellular cytotoxicity (ADCC) responses than mRNA-, vector-, and inactivated virus-based COVID-19 vaccines

Neutralizing antibodies (NAbs) are elicited after infection and vaccination and have been well studied. However, their antibody-dependent cellular cytotoxicity (ADCC) functionality is still poorly characterized. Here, we investigated ADCC activity in convalescent sera from infected patients with wild-type (WT) severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) or omicron variant compared with three coronavirus disease 2019 (COVID-19) vaccine platforms and postvaccination breakthrough infection (BTI). We analyzed ADCC activity targeting SARS-CoV-2 spike (S) and nucleocapsid (N) proteins in convalescent sera following WT SARS-CoV-2-infection (n = 91), including symptomatic and asymptomatic infections, omicron-infection (n = 8), COVID-19 vaccination with messenger RNA- (mRNA)- (BNT162b2 or mRNA-1273, n = 77), adenovirus vector- (n = 41), and inactivated virus- (n = 46) based vaccines, as well as post-mRNA vaccination BTI caused by omicron (n = 28). Correlations between ADCC, binding, and NAb titers were reported. ADCC was elicited within the first month postinfection and -vaccination and remained detectable for ≥3 months. WT-infected symptomatic patients had higher S-specific ADCC levels than asymptomatic and vaccinated individuals. Also, no difference in N-specific ADCC activity was seen between symptomatic and asymptomatic patients, but the levels were higher than the inactivated vaccine. Notably, omicron infection showed reduced overall ADCC activity compared to WT SARS-CoV-2 infection. Although post-mRNA vaccination BTI elicited high levels of binding and NAbs, ADCC activity was significantly reduced. Also, there was no difference in ADCC levels across the four vaccines, although NAbs and binding antibody titers were significantly higher in mRNA-vaccinated individuals. All evaluated vaccine platforms are inferior in inducing ADCC compared to natural infection with WT SARS-CoV-2. The inactivated virus-based vaccine can induce N-specific ADCC activity, but its relevance to clinical outcomes requires further investigation. Our data suggest that ADCC could be used to estimate the extra-neutralization level against COVID-19 and provides evidence that vaccination should focus on other Fc-effector functions besides NAbs. Also, the decreased susceptibility of the omicron variant to ADCC offers valuable guidance for forthcoming efforts to identify the specific targets of antibodies facilitating ADCC.

Bacterial indoor air contaminations in hospitals in MENA region: a systematic review

Poor indoor air quality in healthcare settings has been tied with the increase in hospital-acquired infections. Thus, this systematic review was conducted to assess the levels and compositions of bacteria in indoor hospital air in the Middle East and North Africa (MENA) region. We examined results provided by different search engines published between 2000 and 2021. Our data showed that most studies were conducted in Iran (80.9%) with a bacterial concentration mean of 172.9 CFU/m3. Comparing sensitive and non-sensitive areas of hospitals, no significant difference was detected in the mean bacterial concentration. The most investigated sensitive hospital areas were operating rooms and intensive care units with mean indoor bacterial concentrations of 180.3 CFU/m3 and 204.6 CFU/m3, respectively. Staphylococcaceae, Enterobacteriaceae, Pseudomonadaceae, and Bacillaceae were commonly identified bacterial families. In conclusion, the mean concentrations of the airborne bacteria were within the acceptable limit compared to WHO standards (300 CFU/m3) for the air in areas occupied by immunosuppressed people.

Neutralizing antibodies against SARS-CoV-2 are higher but decline faster in mRNA vaccinees compared to individuals with natural infection

BACKGROUND

Waning protection against emerging SARS-CoV-2 variants by pre-existing antibodies elicited because of current vaccination or natural infection is a global concern. Whether this is due to the waning of immunity to SARS-COV-2 remains unclear.

AIM

We aimed to investigate the dynamics of antibody isotype responses amongst vaccinated naïve (VN) and naturally infected (NI) individuals.

METHODS

We followed up antibody levels in COVID-19 messenger RNA (mRNA)-vaccinated subjects without prior infection (VN, n = 100) in two phases: phase-I (P-I) at ~ 1.4 and phase-II (P-II) at ~ 5.3 months. Antibody levels were compared with those of unvaccinated and naturally infected subjects (NI, n = 40) at ~ 1.7 (P-1) and 5.2 (P-II) months post-infection. Neutralizing antibodies (NTAb), anti-S-RBD-IgG, -IgM and anti-S-IgA isotypes were measured.

RESULTS

The VN group elicited significantly greater antibody responses (P < 0.001) than the NI group at P-I, except for IgM. In the VN group, a significant waning in antibody response was observed in all isotypes. There was about an ~ 4-fold decline in NTAb levels (P < 0.001), anti-S-RBD-IgG (~5-fold, P < 0.001), anti-S-RBD-IgM (~6-fold, P < 0.001) and anti-S1-IgA (2-fold, P < 0.001). In the NI group, a significant but less steady decline was notable in S-RBD-IgM (~2-fold, P < 0.001), and a much smaller but significant difference in NTAb (<2-fold, P < 0.001) anti-S-RBD IgG (<2-fold, P = 0.005). Unlike the VN group, the NI group mounted a lasting anti-S1-IgA response with no significant decline. Anti-S1-IgA, which were ~ 3-fold higher in VN subjects compared with NI in P-1 (P < 0.001), dropped to almost the same levels, with no significant difference observed between the two groups in P-II.

CONCLUSION

Whereas double-dose mRNA vaccination boosted antibody levels, vaccinated individuals' 'boost' was relatively short-lived.

Performance evaluation of novel fluorescent-based lateral flow immunoassay (LFIA) for rapid detection and quantification of total anti-SARS-CoV-2 S-RBD binding antibodies in infected individuals

Background

A vast majority of the commercially available lateral flow immunoassay (LFIA) is used to detect SARS-CoV-2 antibodies qualitatively. Recently, a novel fluorescence-based lateral flow immunoassay (LFIA) test was developed for quantitative measurement of the total binding antibody units (BAUs) (BAU/mL) against SARS-CoV-2 spike protein receptor-binding domain (S-RBD).

Aim

This study aimed to evaluate the performance of the fluorescence LFIA Finecare^TM 2019-nCoV S-RBD test along with its reader (Model No.: FS-113).

Methods

Plasma from 150 reverse trancriptase–PCR (RT-PCR)-confirmed positive individuals and 100 prepandemic samples were tested by Fincare^TM to access sensitivity and specificity. For qualitative and quantitative validation of the FinCare^TM measurements, BAU/mL results of FinCare^TM were compared with results of 2 reference assays: the surrogate virus-neutralizing test (sVNT, GenScript Biotech, USA) and the VIDAS®3 automated assay (BioMérieux, France).

Results

Finecare^TM showed 92% sensitivity and 100% specificity compared with PCR. Cohen's Kappa statistic denoted moderate and excellent agreement with sVNT and VIDAS®3, with values being 0.557 (95% CI: 0.32–0.78) and 0.731 (95% CI: 0.51–0.95), respectively. A strong correlation was observed between Finecare^TM/sVNT (r = 0.7, p < 0.0001) and Finecare^TM/VIDAS®3 (r = 0.8, p < 0.0001).

Conclusion

Finecare^TM is a reliable assay and can be used as a surrogate to assess binding and neutralizing antibody response after infection or vaccination, particularly in none or small laboratory settings.

Low risk of serological cross-reactivity between the dengue virus and SARS-CoV-2 IgG antibodies using advanced detection assays

Several studies have reported serological cross-reactivity of the immune responses between SARS-CoV-2 and DENV. Most of the available studies are based on the point of care (POC) rapid testing kits. However, some rapid test kits have low specificity and can generate false positives. Hence, we aimed to investigate the potential serological cross-reactivity between SARS-CoV-2 and DENV IgG antibodies using advanced assays including chemiluminescence immunoassay (CLIA) and ELISA test. A total of 90 DENV-IgG-ELISA positive and 90 negative pre-pandemic sera were tested for anti-SARS-CoV-2-IgG using the automated CL-900i CLIA assay. Furthermore, a total of 91 SARS-CoV-2-IgG-CLIA positive and 91 negative post-pandemic sera were tested for anti-DENV-IgG using the Novalisa ELISA assay. The DENV-IgG positive sera resulted in five positives and 85 negatives for SARS-CoV-2-IgG. Similarly, the DENV-IgG negative sera also resulted in five positives and 85 negatives for SARS-CoV-2-IgG. No statistically significant difference in specificity between the DENV-IgG positive and DENV-IgG negative sera was found (p-value=1.00). The SARS-CoV-2-IgG positive sera displayed 43 positives, 47 negatives, and one equivocal for DENV-IgG. Whereas the SARS-CoV-2-IgG negative sera resulted in 50 positives, 40 negatives, and one equivocal for DENV-IgG. No statistically significant difference in the proportion that is DENV-IgG positive between the SARS-CoV-2-IgG positive and SARS-CoV-2-IgG negative sera (p-value=0.58). In conclusion, there is a low risk of serological cross-reactivity between the DENV, and SARS-CoV-2 IgG antibodies when using advanced detection assays.  .

Can commercial automated immunoassays be utilized to predict neutralizing antibodies after SARS-CoV-2 infection? A comparative study between three different assays

Background: High-throughput assays that can infer neutralizing activity against SARS-CoV-2 are of great importance for assessing the immunity induced by natural infection and COVID-19 vaccines. We aimed to evaluate the performance and degree of correlation of three fully automated anti-SARS-CoV-2 immunoassays with neutralization activity using a surrogate virus-neutralizing test (sVNT) from GenScript, targeting the receptor-binding domain. Methods: 110 sera collected from PCR-confirmed asymptomatic COVID-19 individuals were tested for neutralizing antibodies (nAbs) using the sVNT. Positive samples were tested on three automated immunoassays targeting different viral antigens: Mindray CL-900i®, Abbott Architect, and Ortho VITROS®. The diagnostic sensitivity, specificity, agreement, and correlation with the sVNT were assessed. Receiver operating characteristic (ROC) curve analysis was performed to determine optimal thresholds for predicting the presence of neutralizing activity by each assay. Results: All three assays showed 100% specificities. The highest sensitivity was 99.0%, demonstrated by VITROS®, followed by 94.3%, for CL-900i®, and 81.0%, for Architect. Both VITROS® and CL-900i® had the strongest correlation with the sVNT (ρ = 0.718 and ρ = 0.712, respectively), while Architect showed a moderate correlation (ρ = 0.618). ROC curve analysis indicated that the manufacturer's recommended cutoff values are adequate for predicting the presence of nAbs and providing a strong correlation with the sVNT. Conclusion: VITROS® and CL-900i® serological assays, which detect antibodies against SARS-CoV-2 spike protein, could serve as reliable assays to predict neutralization activity after infection or vaccination.

Psychological and Coping Strategies Related to Home Isolation and Social Distancing in Children and Adolescents During the COVID-19 Pandemic: Cross-sectional Study

BACKGROUND

In December 2019, a novel coronavirus called SARS-CoV-2 was identified as the cause of a cluster of pneumonia cases in Wuhan, China. It rapidly spread due to human-to-human transmission, resulting in a global pandemic. Nearly every country, including Qatar, has established guidelines and regulations to limit the spread of the virus and to preserve public health. However, these procedures have been associated with negative effects on the psychological and intellectual well-being of individuals, including children and adolescents.

OBJECTIVE

The objective of this study was to determine the psychological influence of home isolation and social distancing on children and adolescents during the COVID-19 pandemic in Qatar, and the strategies used to cope with these measures.

METHODS

This cross-sectional study was undertaken using an online questionnaire administered through SMS text messaging. All home-isolated children and adolescents registered at the Primary Health Care Corporation aged 7-18 years were invited to participate in the study. Children and adolescents with intellectual disadvantages were excluded. A P value of .05 (two-tailed) was considered statistically significant.

RESULTS

Data were collected from 6608 participants from June 23 to July 18, 2020. Nearly all participants adhered to the official regulations during the period of home isolation and social distancing; however, 69.1% (n=4568) of parents believed their children were vulnerable to the virus compared to 25% (n=1652) who expressed they were not vulnerable at all. Higher levels of anger, depression, and general anxiety were prevalent among 1.3% (n=84), 3.9% (n=260), and 1.6% (n=104) of participants, respectively. The mean score for the emotional constructs anger and depression decreased with increased compliance with regulations (P=.04 and P=.11, respectively). The differences in mean score for all psychological and coping strategies used among participants across the 3 levels of vulnerability to SARS-CoV-2 were statistically significant. The mean score varied little with increasing reported vulnerability to the virus. This mild variation can make a difference when the sample size is large, as is the case in this study.

CONCLUSIONS

Screening for psychological and social disruptions is important for the development of strategies by schools and health care providers to assess and monitor behavioral changes and negative psychological impact during post-COVID-19 reintegration. Participants experiencing higher levels of anxiety should be given more attention during reintegration and transitional phases in schools. Although electronic devices and social media platforms may have lowered anxiety levels in some cases, it is important to address how they are used and how content is tailored to children and adolescents. It is also important to maintain an active lifestyle for children and young persons, and encourage them not to neglect their physical health, as this promotes a better psychological state of mind.

Diagnostic Efficiency of Three Fully Automated Serology Assays and Their Correlation with a Novel Surrogate Virus Neutralization Test in Symptomatic and Asymptomatic SARS-COV-2 Individuals

To support the deployment of serology assays for population screening during the COVID-19 pandemic, we compared the performance of three fully automated SARS-CoV-2 IgG assays: Mindray CL-900i® (target: spike [S] and nucleocapsid [N]), BioMérieux VIDAS®3 (target: receptor-binding domain [RBD]) and Diasorin LIAISON®XL (target: S1 and S2 subunits). A total of 111 SARS-CoV-2 RT-PCR- positive samples collected at ≥ 21 days post symptom onset, and 127 pre-pandemic control samples were included. Diagnostic performance was assessed in correlation to RT-PCR and a surrogate virus-neutralizing test (sVNT). Moreover, cross-reactivity with other viral antibodies was investigated. Compared to RT-PCR, LIAISON®XL showed the highest overall specificity (100%), followed by VIDAS®3 (98.4%) and CL-900i® (95.3%). The highest sensitivity was demonstrated by CL-900i® (90.1%), followed by VIDAS®3 (88.3%) and LIAISON®XL (85.6%). The sensitivity of all assays was higher in symptomatic patients (91.1-98.2%) compared to asymptomatic patients (78.4-80.4%). In correlation to sVNT, all assays showed excellent sensitivities (92.2-96.1%). In addition, VIDAS®3 demonstrated the best correlation (r = 0.75) with the sVNT. The present study provides insights on the performance of three fully automated assays, which could help diagnostic laboratories in the choice of a particular assay according to the intended use.

Performance evaluation of five ELISA kits for detecting anti-SARS-COV-2 IgG antibodies

Objectives

To evaluate and compare the performances of five commercial ELISA assays (EDI, AnshLabs, Dia.Pro, NovaTec, and Lionex) for detecting anti-SARS-CoV-2 IgG.

Methods

Seventy negative control samples (collected before the COVID-19 pandemic) and samples from 101 RT-PCR-confirmed SARS-CoV-2 patients (collected at different time points from symptom onset: ≤7, 8–14 and >14 days) were used to compare the sensitivity, specificity, agreement, and positive and negative predictive values of each assay with RT-PCR. A concordance assessment between the five assays was also conducted. Cross-reactivity with other HCoV, non-HCoV respiratory viruses, non-respiratory viruses, and nuclear antigens was investigated.

Results

Lionex showed the highest specificity (98.6%; 95% CI 92.3–99.8), followed by EDI and Dia.Pro (97.1%; 95% CI 90.2–99.2), NovaTec (85.7%; 95% CI 75.7–92.1), then AnshLabs (75.7%; 95% CI 64.5–84.2). All ELISA kits cross-reacted with one anti-MERS IgG-positive sample, except Lionex. The sensitivity was low during the early stages of the disease but improved over time. After 14 days from symptom onset, Lionex and NovaTec showed the highest sensitivity at 87.9% (95% CI 72.7–95.2) and 86.4% (95% CI 78.5–91.7), respectively. The agreement with RT-PCR results based on Cohen’s kappa was as follows: Lionex (0.89) > NovaTec (0.70) > Dia.Pro (0.69) > AnshLabs (0.63) > EDI (0.55).

Conclusion

The Lionex and NovaLisa IgG ELISA kits, demonstrated the best overall performance.

Vitamin D status among adults (18-65 years old) attending primary healthcare centres in Qatar: a cross-sectional analysis of the Electronic Medical Records for the year 2017

OBJECTIVES

To investigate the prevalence of vitamin D deficiency among individuals attending primary healthcare facilities in Qatar and to assess the association between vitamin D deficiency and some medical conditions in persons aged 18-65 years old.

SETTING

The study was undertaken in publicly funded primary healthcare services in the State of Qatar.

PARTICIPANTS

A total of 102 342 participants aged between 18 and 65 years old with a valid serum vitamin D test result during the year 2017.

OUTCOME MEASURES

Serum level <10 ng/mL (<25 nmol/L) was defined as severe vitamin D deficiency, a serum level of <20 ng/mL (<50 nmol/L) was defined as vitamin D deficiency and a serum level <30 ng/mL (<75 nmol/L) defined as vitamin D insufficiency.

RESULTS

The prevalence rate of severe vitamin D deficiency was 14.1% among study participants with no history of vitamin D replacement therapy in the previous months. The prevalence rate of vitamin D deficiency was as high as 71.4% and that of vitamin D insufficiency was up to 92.7%. None of the five chronic conditions explored in the study (diabetes, hypertension, asthma, stroke and cardiovascular disease) had an obvious association with severe vitamin D deficiency status in a bivariate analysis. However, multivariate modelling showed that (adjusting for age, gender, body mass index and nationality and each of the included chronic conditions) hypertension, cardiovascular diseases and stroke placed an individual at a higher risk of having an associated severe vitamin D deficiency status.

CONCLUSION

Although not comprehensive and nationally representative, this study is suggestive of a higher prevalence of vitamin D deficiency among young adults, females, Qatari nationality and those with higher body mass index. Multivariate modelling showed that hypertension, cardiovascular diseases and stroke were associated with a higher risk of severe vitamin D deficiency status.

Anthropometric measurements and dietary habits of schoolchildren in Qatar

INTRODUCTION

Very little is known about the anthropometric measurements and dietary habits of children in the Arabian Gulf in general, and in Qatar in particular.

OBJECTIVES

To conduct anthropometrics measurements on schoolchildren in Qatar and to explore their dietary habits.

METHODS

A cross-sectional study was carried out, targeting 271 (124 male and 147 female) primary school students.

RESULTS

Using the body mass index as the index of adiposity, 54.8% and 23.1% of Grade One male and female children were underweight, 3.2% and 8.8% were overweight, and 1.6% and 5.4% were obese, respectively. Breakfast, lunch, and dinner were eaten by 65%, 86%, and 87% on a daily basis. Anthropometric measurements differed significantly (P < 0.05) between genders and the other children of the National Center for Health Statistics population.

CONCLUSION

schoolchildren in Qatar may be considered as having less overweight and obesity occurrence than most children in the Gulf.