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BackgroundInactivated SARS-CoV-2 (CoronaVac(R),Sinovac, or SV) and ChAdOx1 nCoV-19 (Vaxzevria(R),Oxford-Astra Zeneca, or AZ) vaccines have been administered to the health care workers (HCWs) in Thailand. ObjectiveTo determine the short-term immune response after the SV and AZ vaccinations in HCWs. MethodsIn this prospective cohort study, HCWs who completed a 2-dose regimen of the SV or AZ were included. Immune response was evaluated by surrogate viral neutralization test (sVNT) and anti-SARS-CoV-2 total antibody. Blood samples were analyzed at 4 and 12 weeks after the complete SV vaccination and at 4 weeks after each dose of the AZ vaccination. The primary outcome was the seroconversion rate at 4-weeks after complete immunization. ResultsOverall, 185 HCWs with a median (IQR) age of 40.5(30.3-55.8) years (94 HCWs in the SV group and 91 in the AZ group) were included. At 4 weeks after completing the SV vaccination, 60.6% (95%CI:50.0-70.6%) had seroconversion evaluated by sVNT([≥]68%inhibition), comparable to the patients recovered from mild COVID-19 infection(69.0%), with a rapid reduction to 12.2%(95%CI:6.3-20.8) at 12 weeks. In contrast, 85.7%(95%CI:76.8-92.2%) HCWs who completed the second dose of the AZ for 4 weeks had seroconversion, comparable to the COVID-19 pneumonia patients(92.5%). When using the anti-SAR-CoV-2 total antibody level([≥]132 U/ml) criteria, only 71.3% HCWs in the SV group had seroconversion, compared to 100% in the AZ group. ConclusionA rapid decline of short-term immune response in the HCWs after the SV vaccination indicates the need for a vaccine booster, particularly during the ongoing spreading of the SAR-CoV-2 variants of concern.
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BackgroundMore understanding of antibody responses in the SARS-CoV-2 infected population is useful for vaccine development. AimTo investigate SARS-CoV-2 IgA and IgG among COVID-19 Thai patients with different severity. MethodsWe used plasma from 118 adult patients who have confirmed SARS-CoV-2 infection and 49 patients under investigation without infection, 20 patients with other respiratory infections, and 102 healthy controls. Anti-SARS-CoV-2 IgA and IgG were performed by enzyme-linked immunosorbent assay from Euroimmun. The optical density ratio cut off for positive test was 1.1 for IgA and 0.8 for IgG. The association of antibody response with the severity of diseases and the day of symptoms was performed. ResultsFrom Mar 10 to May 31, 2020, 289 participants were enrolled, and 384 samples were analyzed. Patients were categorized by clinical manifestations to mild (n = 59), moderate (n = 27) and severe (n = 32). The overall sensitivity of IgA and IgG from samples collected after day 7 is 87.9% (95% CI 79.8-93.6) and 84.8% (95% CI 76.2-91.3), respectively. The severe group had a significantly higher level of specific IgA and IgG to S1 antigen compared to the mild group. All moderate to severe patients have specific IgG while 20% of the mild group did not have any IgG detected after two weeks. Interestingly, SARS-CoV-2 IgG level was significantly higher in males compared to females among the severe group (p = 0.003). ConclusionThe serologic test for SARS-CoV-2 has high sensitivity after the second week after onset of illness. Serological response differs among patients with different severity and different sex.
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PurposeWhen severe, COVID-19 shares many clinical features with bacterial sepsis. Yet, secondary bacterial infection is uncommon. However, as epithelium are injured and barrier function is lost, bacterial products entering the circulation might contribute to the pathophysiology of COVID-19. MethodsWe studied 19 adults, severely ill patients with COVID-19 infection, who were admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between 13th March and 17th April 2020. Blood samples on day 1, 3, and 7 of enrollment were analyzed for endotoxin activity assay (EAA), (1[->]3)-{beta}-D-Glucan (BG), and 16S rRNA gene sequencing to determine the circulating bacteriome. ResultsOf the 19 patients, 14 were in intensive care and 10 patients received mechanical ventilation. We found 8 patients with high EAA ([≥] 0.6) and about half of the patients had high serum BG levels which tended to be higher in later in the illness. Although only 1 patient had a positive blood culture, 18 of 19 patients were positive for 16S rRNA gene amplification. Proteobacteria was the most abundant phylum. The diversity of bacterial genera was decreased overtime. ConclusionsBacterial DNA and toxins were discovered in virtual all severely ill COVID-19 pneumonia patients. This raises a previously unrecognized concern for significant contribution of bacterial products in the pathogenesis of this disease
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In the age of a pandemic, such as the ongoing one caused by SARS-CoV-2, the world faces limited supply of tests, PPE and reagents, and factories are struggling to meet the growing demands. This study aimed to evaluate the efficacy of pooling specimen for testing of SARS-CoV-2 virus, to determine whether costs and resource savings could be achieved without impacting the sensitivity of the testing. Ten specimens were pooled for testing, containing either one or two known positive specimen of varying viral concentrations. Pooling specimens did not affect the sensitivity of detecting SARS-CoV-2, and the PCR cycle threshold (Ct) between testing of pooling specimen and subsequent individual testing was not significantly different using paired t-test. This study also identified cost savings garnered from pooling of specimen for testing at 4 differing prevalence rates, ranging from 0.1-10%. Pooling specimens to test for COVID-19 infection in low prevalence areas or in low risk population can dramatically decrease the resources burden on lab operations by up to 80%. This paves the possibility for large-scale population screening, allowing for assured policy decisions by governmental bodies to ease lockdown restrictions in areas with low incidence of infection, or with lower risk populations.