Evaluation of post-vaccination immunoglobulin G antibodies and T-cell immune response after inoculation with different types and doses of SARS-CoV-2 vaccines: A retrospective cohort study.

Introduction: The induction and speed of production of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) immune biomarkers may vary by type and number of inoculated vaccine doses. This study aimed to explore variations in SARS-CoV-2 anti-spike (anti-S), anti-nucleocapsid (anti-N), and neutralizing immunoglobulin G (IgG) antibodies, and T-cell response by type and number of SARS-CoV-2 vaccine doses received. Methods: In a naturally exposed and SARS-CoV-2-vaccinated population, we quantified the anti-S, anti-N, and neutralizing IgG antibody concentration and assessed T-cell response. Data on socio-demographics, medical history, and history of SARS-CoV-2 infection and vaccination were collected. Furthermore, nasal swabs were collected to test for SARS-CoV-2 infection. Confounder-adjusted association between having equal or more than a median concentration of the three IgG antibodies and T-cell response by number and type of the inoculated vaccines was quantified. Results: We surveyed 952 male participants with a mean age of 35.5 years ± 8.4 standard deviations. Of them, 52.6% were overweight/obese, and 11.7% had at least one chronic comorbidity. Of the participants, 1.4, 0.9, 20.2, 75.2, and 2.2% were never vaccinated, primed with only one dose, primed with two doses, boosted with only one dose, and boosted with two doses, respectively. All were polymerase chain reaction-negative to SARS-CoV-2. BBIBP-CorV (Sinopharm) was the most commonly used vaccine (92.1%), followed by rAd26-S + rAd5-S (Sputnik V Gam-COVID-Vac) (1.5%) and BNT162b2 (Pfizer-BioNTech) (0.3%). Seropositivity to anti-S, anti-N, and neutralizing IgG antibodies was detected in 99.7, 99.9, and 99.3% of the study participants, respectively. The T-cell response was detected in 38.2% of 925 study participants. Every additional vaccine dose was significantly associated with increased odds of having ≥median concentration of anti-S [adjusted odds ratio (aOR), 1.34; 95% confidence interval (CI): 1.02-1.76], anti-N (aOR, 1.35; 95% CI: 1.03-1.75), neutralizing IgG antibodies (aOR, 1.29; 95% CI: 1.00-1.66), and a T-cell response (aOR, 1.48; 95% CI: 1.12-1.95). Compared with boosting with only one dose, boosting with two doses was significantly associated with increased odds of having ≥median concentration of anti-S (aOR, 13.8; 95% CI: 1.78-106.5), neutralizing IgG antibodies (aOR, 13.2; 95% CI: 1.71-101.9), and T-cell response (aOR, 7.22; 95% CI: 1.99-26.5) although not with anti-N (aOR, 0.41; 95% CI: 0.16-1.08). Compared with priming and subsequently boosting with BBIBP-CorV, all participants who were primed with BBIBP-CorV and subsequently boosted with BNT162b2 had ≥median concentration of anti-S and neutralizing IgG antibodies and 14.6-time increased odds of having a T-cell response (aOR, 14.63; 95% CI: 1.78-120.5). Compared with priming with two doses, boosting with the third dose was not associated, whereas boosting with two doses was significantly associated with having ≥median concentration of anti-S (aOR, 14.20; 95% CI: 1.85-109.4), neutralizing IgG (aOR, 13.6; 95% CI: 1.77-104.3), and T-cell response (aOR, 7.62; 95% CI: 2.09-27.8). Conclusion: Achieving and maintaining a high blood concentration of protective immune biomarkers that predict vaccine effectiveness is very critical to limit transmission and contain outbreaks. In this study, boosting with only one dose or with only BBIBP-CorV after priming with BBIBP-CorV was insufficient, whereas boosting with two doses, particularly boosting with the mRNA-based vaccine, was shown to be associated with having a high concentration of anti-S, anti-N, and neutralizing IgG antibodies and producing an efficient T-cell response.

Evaluation of post-vaccination immunoglobulin G antibodies and T-cell immune response after inoculation with different types and doses of SARS-CoV-2 vaccines: A retrospective cohort study

Introduction The induction and speed of production of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) immune biomarkers may vary by type and number of inoculated vaccine doses. This study aimed to explore variations in SARS-CoV-2 anti-spike (anti-S), anti-nucleocapsid (anti-N), and neutralizing immunoglobulin G (IgG) antibodies, and T-cell response by type and number of SARS-CoV-2 vaccine doses received. Methods In a naturally exposed and SARS-CoV-2–vaccinated population, we quantified the anti-S, anti-N, and neutralizing IgG antibody concentration and assessed T-cell response. Data on socio-demographics, medical history, and history of SARS-CoV-2 infection and vaccination were collected. Furthermore, nasal swabs were collected to test for SARS-CoV-2 infection. Confounder-adjusted association between having equal or more than a median concentration of the three IgG antibodies and T-cell response by number and type of the inoculated vaccines was quantified. Results We surveyed 952 male participants with a mean age of 35.5 years ± 8.4 standard deviations. Of them, 52.6% were overweight/obese, and 11.7% had at least one chronic comorbidity. Of the participants, 1.4, 0.9, 20.2, 75.2, and 2.2% were never vaccinated, primed with only one dose, primed with two doses, boosted with only one dose, and boosted with two doses, respectively. All were polymerase chain reaction-negative to SARS-CoV-2. BBIBP-CorV (Sinopharm) was the most commonly used vaccine (92.1%), followed by rAd26-S + rAd5-S (Sputnik V Gam-COVID-Vac) (1.5%) and BNT162b2 (Pfizer-BioNTech) (0.3%). Seropositivity to anti-S, anti-N, and neutralizing IgG antibodies was detected in 99.7, 99.9, and 99.3% of the study participants, respectively. The T-cell response was detected in 38.2% of 925 study participants. Every additional vaccine dose was significantly associated with increased odds of having ≥median concentration of anti-S [adjusted odds ratio (aOR), 1.34;95% confidence interval (CI): 1.02–1.76], anti-N (aOR, 1.35;95% CI: 1.03–1.75), neutralizing IgG antibodies (aOR, 1.29;95% CI: 1.00–1.66), and a T-cell response (aOR, 1.48;95% CI: 1.12–1.95). Compared with boosting with only one dose, boosting with two doses was significantly associated with increased odds of having ≥median concentration of anti-S (aOR, 13.8;95% CI: 1.78–106.5), neutralizing IgG antibodies (aOR, 13.2;95% CI: 1.71–101.9), and T-cell response (aOR, 7.22;95% CI: 1.99–26.5) although not with anti-N (aOR, 0.41;95% CI: 0.16–1.08). Compared with priming and subsequently boosting with BBIBP-CorV, all participants who were primed with BBIBP-CorV and subsequently boosted with BNT162b2 had ≥median concentration of anti-S and neutralizing IgG antibodies and 14.6-time increased odds of having a T-cell response (aOR, 14.63;95% CI: 1.78–120.5). Compared with priming with two doses, boosting with the third dose was not associated, whereas boosting with two doses was significantly associated with having ≥median concentration of anti-S (aOR, 14.20;95% CI: 1.85–109.4), neutralizing IgG (aOR, 13.6;95% CI: 1.77–104.3), and T-cell response (aOR, 7.62;95% CI: 2.09–27.8). Conclusion Achieving and maintaining a high blood concentration of protective immune biomarkers that predict vaccine effectiveness is very critical to limit transmission and contain outbreaks. In this study, boosting with only one dose or with only BBIBP-CorV after priming with BBIBP-CorV was insufficient, whereas boosting with two doses, particularly boosting with the mRNA-based vaccine, was shown to be associated with having a high concentration of anti-S, anti-N, and neutralizing IgG antibodies and producing an efficient T-cell response.

Susceptibility to reinfection with SARS-CoV-2 virus relative to existing antibody concentrations and T cell response.

OBJECTIVES: We investigated the reinfection rate of vaccinated or convalescent immunized SARS-CoV-2 in 952 expatriate workers with SARS-CoV-2 serological antibody (Ab) patterns and surrogate T cell memory at recruitment and follow-up. METHODS: Trimeric spike, nucleocapsid, and neutralizing Abs were measured, along with a T cell stimulation assay, targeting SARS-CoV-2 memory in clusters of differentiation (CD) 4+ and CD8+ T cells. The subjects were then followed up for reinfection for up to 6 months. RESULTS: The seroprevalence positivity at enrollment was greater than 99%. The T cell reactivity in this population was 38.2%. Of the 149 (15.9%) participants that were reinfected during the follow-up period (74.3%) had nonreactive T cells at enrollment. Those who had greater than 100 binding Ab units/ml increase from the median concentration of antispike immunoglobulin G Abs had a 6% reduction in the risk of infection. Those who were below the median concentration had a 78% greater risk of infection. CONCLUSION: Significant immune protection from reinfection was observed in those who retained T cell activation memory. Additional protection was observed when the antispike was greater than the median value.

Seroprevalence of COVID-19 infection in the Emirate of Abu Dhabi, United Arab Emirates: a population-based cross-sectional study.

BACKGROUND: The United Arab Emirates (UAE) was the first country in the Middle East to report severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Serosurveys are essential to understanding the extent of virus transmission. This cross-sectional study aims to assess the seroprevalence of SARS-CoV-2 infection in the Emirate of Abu Dhabi. METHODS: Between 19 July and 14 August 2020, 4487 households were selected using a random sample stratified by region and citizenship of the head of household (UAE citizen or non-citizen). A cluster sample of 40 labour camps was selected. Data on socio-demographic characteristics, risk factors and symptoms compatible with coronavirus disease 2019 (COVID-19) were collected. Each participant was first tested by Roche Elecsys® Anti-SARS-CoV-2 assay, followed, when reactive, by the LIAISON® SARS-CoV-2 S1/S2 IgG assay. RESULTS: Among 8831 individuals from households, seroprevalence was 10·4% [95% confidence intervals (CIs) 9·5-11·4], with higher seroprevalence in Abu Dhabi and Al Ain regions compared with those in Al Dhafra. In households, we found no sex difference and UAE citizens had lower seroprevalence compared with those of other nationalities. Among 4855 workers residing in labour camps, seroprevalence was 68·6% (95% CI 61·7-74·7), with higher seroprevalence among workers from Southeast Asia. In households, individuals with higher body mass indexes demonstrated higher seroprevalences than individuals with normal weight. Anosmia and ageusia were strongly associated with seropositivity. CONCLUSIONS: The majority of household populations in the Emirate of Abu Dhabi remained unexposed to SARS-CoV-2. In labour camps, SARS-CoV-2 transmission was high. Effective public health measures should be maintained.

Evaluation of three commercial SARS-CoV-2 serology assays in a tertiary care hospital in the United Arab Emirates.

BACKGROUND: Serology assays have the potential to support RT-PCR in the diagnosis of SARS-CoV-2 infection. We studied three commercially available immunoassays for their diagnostic accuracy from blood specimens collected from 93 patients. METHODS: Blood samples from patients with confirmed COVID-19 infection were analysed using three different Immunoassays (Roche total antibody assay, Abbott IgG assay and Euroimmun IgG assay). Sensitivity, specificity, precision and time of seroconversion were evaluated. RESULTS: The sensitivity of Roche, Abbott and Euroimmun assays was 38.7%, 35.5% and 25.0% respectively for specimens collected <10 days and 84.4%, 84.4% and 70.0% respectively for specimens collected ≥10 days after the first positive RT-PCR. The specificity of all the three assays in this study was 100%. The timing of seroconversion occurred at day 1, 7 or 14. CONCLUSIONS: The assays evaluated in this study have different sensitivities for detecting antibodies in SARS-CoV-2 infection. Sensitivity for detecting antibodies for all three assays was higher for specimens collected ≥10 days after first positive PCR compared with specimens collected <10 days. Time of seroconversion is variable and assay-dependent.

Saliva as an Alternative Specimen for Molecular COVID-19 Testing in Community Settings and Population-Based Screening.

PURPOSE: With the easing of restriction measures, repeated community-based sampling for tracking new COVID-19 infections is anticipated for the next 6 to 12 months. A non-invasive, self-collected specimen like saliva will be useful for such public health surveillance. Investigations on the use of saliva for SARS-CoV-2 RT-PCR have largely been among COVID-19 in-pa\tients and symptomatic ambulatory patients with limited work in a community-based screening setting. This study was carried out to address this paucity of data and reported discrepancies in diagnostic accuracy for saliva samples. PATIENTS AND METHODS: From 29th June to 14th July 2020, adults presenting for COVID-19 testing at a community-based screening facility in Dubai, United Arab Emirates were recruited. Clinical data, nasopharyngeal swab in universal transport media and drooling saliva in sterile containers were obtained. Reverse transcriptase PCR amplification of SARS-CoV-2 RdRp and N genes was used to detect the presence of the SARS-CoV-2 virus. RESULTS: Of the 401 participants, 35 (8.7%) had viral detection in at least one specimen type and the majority (n=20/35; 57.1%) were asymptomatic. Both swab and saliva were positive in 19 (54.2%) patients, while 7 (20.0%) patients had swab positive/saliva negative results. There were 9 (25.7%) patients with saliva positive/swab negative result and this included 5 asymptomatic COVID-19 patients undergoing repeat screening. Using the swab as the reference gold standard, the sensitivity and specificity of saliva were 73.1% (95% CI 52.2-88.4%) and 97.6% (95% CI 95.5-98.9%) while the positive and negative predictive values were 67.9% (95% CI 51.5-80.8%) and 98.1% (95% CI 96.5-99.0%), respectively. CONCLUSION: The findings suggest good diagnostic accuracy for saliva and feasibility of utilization of specimen without transport media for SARS-CoV-2 RT-PCR. Saliva represents a potential specimen of choice in community settings and population-based screening.