ABSTRACT
Immunogenicity following inactivated SARS-CoV-2 vaccination among solid organ transplant recipients has not been assessed. Seventy-five patients (37 kidney transplant [KT] recipients and 38 non-transplant controls) received two doses, at 4-week intervals, of an inactivated whole-virus SARS-CoV-2 vaccine. SARS-CoV-2-specific humoral (HMI) and cell-mediated immunity (CMI) were measured before, 4 weeks post-first dose, and 2 weeks post-second dose. The median age of KT recipients was 50 years (IQR, 42-54) and 89% were receiving calcineurin inhibitors/mycophenolate/corticosteroid regimens. The median time since transplant was 4.5 years (IQR, 2-9.5). Among 35 KT patients, anti-RBD IgG titer after vaccination was not significantly different to baseline, but was significantly lower than in controls (7.8 [95%CI 0.2-15.5] vs 2,691 [95%CI 1,581-3,802], p<0.001) as well as the percentage of surrogate virus neutralizing antibody inhibition (2 [95% CI -1-6] vs 71 [95%CI 61-81], p<0.001). However, the mean of SARS-CoV-2 mixed peptides-specific T-cell responses measured by enzyme-linked immunospot assays was significantly increased compared with baseline (66 [95%CI 36-99] vs. 34 [95%CI 19-50] T-cells/106 PBMCs, p=0.02) and comparable to that in controls. Our findings revealed weak HMI and marginal CMI responses in fully vaccinated KT recipients receiving inactivated SARS-CoV-2 vaccine. (Thai Clinical Trials Registry, TCTR20210226002).
ABSTRACT
We presented an initial pilot study report focused on immunogenicity and safety following an inactivated whole-virus severe acute respiratory syndrome coronavirus 2 vaccination among kidney transplant (KT) recipients. At four weeks after the first dose of vaccine, the level of anti-receptor-binding domain IgG antibody was not significantly different compared to before vaccination in 30 KT recipients (p = 0.45). Moreover, a significant lower mean (95% CI) anti-receptor-binding domain IgG antibody was observed compared to 30 immunocompetent controls (2.4 [95% CI 1.3-3.5] vs. 173.1 [95% CI 88.3-2,457.9] AU/mL, p < 0.001). Mild adverse events included fever (17%) and localized pain at the injection site (14%) were observed after vaccination.
ABSTRACT
IntroductionVaccine-induced thrombotic thrombocytopenia (VITT) has been reported after vaccination with the adenoviral vector COVID-19 vaccine ChAdOx1 nCoV-19 in European countries. To date, no case of VITT has been reported in Thais after COVID-19 vaccination. We determined the frequency of anti-PF4/polyanionic antibodies in the Thai population receiving the COVID-19 vaccines. MethodsWe conducted a cross-sectional study to evaluate the prevalence of anti-PF4/polyanionic antibodies in health care workers who received COVID-19 vaccination with ChAdOx1 nCoV-19 or CoronaVac within 7-35 days. A control population who had not been vaccinated was also included. Anti-PF4/polyanionic antibodies were detected using enzyme-link immunosorbent assay (ELISA). Functional assay with platelet aggregation was performed for all positive anti-PF4/polyanionic antibody ELISA tests. ResultsA total of 646 participants were included in the study. 221 received ChAdOx1 nCoV-19, 232 received CoronaVac, and 193 participants were in the control group. The prevalence of anti-PF4 antibodies was 2.3% (95% confidence interval [CI] 0.7 to 5.2), 1.7% (95% CI, 0.5 to 4.4) in the ChAdOx1 nCoV-19 and CoronaVac groups, respectively. There was no positive test in the control group. None of the PF4/polyanionic positive sera induced platelet aggregation. ConclusionWe found a low prevalence of anti-PF4 antibodies in Thais after vaccination with ChAdOx1 nCoV-19 and CoronaVac. Low titer positive PF4/polyanionic ELISA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19. HighlightsO_LIHigh titer PF4/polyanion antibodies are associated with vaccine-induced immune thrombotic thrombocytopenia (VITT). C_LIO_LILow titer PF4/polyanion antibodies occur after vaccination with ChAdOx1 nCoV-19 and CoronaVac in some vaccinees. C_LIO_LIThese PF4/polyanion antibodies do not activate platelets and lack of association with VITT. C_LIO_LILow-titer positive PF4/polyanionic ELISA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19. C_LI
ABSTRACT
Recent surges in SARS-CoV-2 variants of concern (VOCs) call for the need to evaluate levels of vaccine-and infection-induced SARS-CoV-2 neutralizing antibodies (NAbs). CoronaVac (Sinovac Biotech, Beijing, China) is currently being used for mass vaccination in Thailand as well as other low-income countries. Three VOCs currently circulating within Thailand include the B.1.1.7 (Alpha), B.1.351 (Beta), and B.1.617.2 (Delta) strains. We assessed NAb potency against the prototypic strain containing the original spike sequence (WT) compared to that against the 3 VOCs using sera derived from a cohort of healthcare workers who received a full 2-dose regimen of CoronaVac. Sera from two other cohorts consisting of COVID-19 patients who had been hospitalized in 2020 and 2021 were evaluated for comparison. We found that, despite equally robust production of S1-RBD-binding IgG and 100% seropositivity, sera from both CoronaVac vaccinees and naturally infected individuals had significantly reduced neutralizing capacity against all 3 VOCs compared to WT. Strikingly, NAb titers against Alpha and Beta were comparable, but Delta appears to be significantly more refractory to NAbs in all groups. Our results may help inform on CoronaVac NAb-inducing capacity, which is a proxy for vaccine efficacy, in the context of the WT strain and 3 VOCs. Our results also have critical implications for public health decision-makers who may need to maintain efficient mitigation strategies amid a potentially high risk for infection with VOCs even in those who have been previously infected.
ABSTRACT
ObjectivesAmid the increasing number of global pandemic coronavirus disease 2019 (COVID-19) cases, there is a need for a quick and easy method to obtain a non-invasive sample for the detection of this novel coronavirus 2019 (SARS-CoV-2). We aimed to investigate the potential use of saliva samples as a non-invasive tool for the diagnosis of COVID-19. MethodsFrom 27 March to 4 April, 2020, we prospectively collected saliva samples and a standard nasopharyngeal and throat swab in persons seeking care at an acute respiratory infection clinic in a university hospital during the outbreak of COVID-19. Real-time polymerase chain reaction (RT-PCR) was performed, and the results of the two specimens were compared. ResultsTwo-hundred pairs of the samples were collected. Sixty-nine (34.5%) patients were male, and the median (interquartile) age was 36 (28-48) years. Using nasopharyngeal and throat swab RT-PCR as the reference standard, the prevalence of COVID-19 diagnosed by nasopharyngeal and throat swab RT-PCR was 9.5%. The sensitivity and specificity of the saliva sample RT-PCR were 84.2% [95% confidence interval (CI) 79.2%-89.3%], and 98.9% (95% CI 97.5-100.3%), respectively. An analysis of the agreement between the two specimens demonstrated 97.5% observed agreement (kappa coefficient 0.851, 95% CI 0.723-0.979; p <0.001). ConclusionsSaliva specimens can be used for the diagnosis of COVID-19. The collection method is non-invasive, and non-aerosol generating. Using a saliva sample as a specimen for the detection of SARS-CoV-2 could facilitate the diagnosis of the disease, which is one of the strategies that helps in controlling the epidemic.