The Panbio COVID-19 Ag Rapid Test: Which Performances are for COVID-19 Diagnosis?

BACKGROUND: Rapid antigen detection assays are promising tools for the diagnosis of COVID-19. We assess the performances of the Panbio COVID-19 Ag Rapid Test. METHODS: The Panbio COVID-19 Ag Rapid test was compared to a reference RT-PCR performed on the same nasopharyngeal swab (NPS). Overall, 81 NPS were tested retrospectively and 330 healthcare workers (HCWs) were tested prospectively. RESULTS: Retrospective analyze. Of the 48 SARS-CoV-2 positive NPS, 19 (39.6%) were found positive with the Panbio COVID-19. There was no cross-reactivity with SARS-CoV-2 negative NPS. The Kappa value was 0.459. Prospective analyze. The prevalence of COVID-19 was 26.1% in symptomatic HCWs. The overall sensitivity and specificity of the Panbio COVID-19 were 47.2% and 100.0% respectively. The sensitivity was 55.2% and 14.3% in those tested within and after 4 days of diseases respectively. CONCLUSIONS: The Panbio COVID-19 Ag Rapid test displays low performance for the identification of SARS-CoV-2 infected patients.

An Immunogenicity Report for the Comparison between Heterologous and Homologous Prime-Boost Schedules with ChAdOx1-S and BNT162b2 Vaccines.

BACKGROUND: There is a small amount of immunological data on COVID-19 heterologous vaccination schedules in humans. We assessed the immunogenicity of BNT162b2 (Pfizer/BioNTech) administered as a second dose in healthcare workers primed with ChAdOx1-S (Vaxzevria, AstraZeneca). METHODS: 197 healthcare workers were included in a monocentric observational study in Foch hospital, France, between June and July 2021. The main outcome was the immunogenicity measured by serum SARS-CoV-2 IgG antibodies. RESULTS: 130 participants received the ChAdOx1-S/BNT vaccine and 67 received the BNT/BNT vaccine. The geometric mean of IgG antibodies was significantly higher in the BNT/BNT vaccine group compared to the ChAdOx1-S/BNT vaccine group, namely 10,734.9, 95% CI (9141.1-12,589.3) vs. 7268.6, 95% CI (6501.3-8128.3), respectively (p < 0.001). However, after adjustment for time duration between the prime and second vaccinations, no significant difference was observed (p = 0.181). A negative correlation between antibody levels and time duration between second dose and serology test was observed for the BNT/BNT vaccine (p < 0.001), which remained significant after adjustment for all covariates (p < 0.001), but not for the ChAdOx1-S/BNT vaccine (p = 0.467). CONCLUSIONS: Heterologous and homologous schedules of ChAdOx1-S and BNT vaccines present robust immune responses after the second vaccination. The results observed were equivalent after adjustment for covariates and emphasize the importance of flexibility in deploying mRNA and viral vectored vaccines. Nevertheless, applying the ChAdOx1-S schedule vaccination for the heterologous second dose of BNT was associated with decreased IgG antibody levels compared to the homologous BNT/BNT vaccination.

SARS-CoV-2 screening of asymptomatic health care workers: experience of a General hospital.

Health care workers (HCWs) are at major risk to be infected by SARS-CoV-2 and transmit the virus to the patients. Furthermore, travels are a major factor in the diffusion of the virus. We report our experience regarding the screening of asymptomatic HCWs returning from holidays, following the issue of a national guideline on 08/20/2020. The organization of the occupational health department and the clinical laboratory was adapted in order to start the screening on August, 24, 2020. All HCWs tested for SARS-CoV-2 the week before and 4 weeks after the implementation of the screening were included. The mean number of tests was analyzed per working day and working week. Overall, 502 (31.4%) HCWs were tested for SARS-CoV-2 during the study period. The mean number of HCWs tested per working day was 27.1. HCWs accounted for 36.9% (n = 167) and 11.2% (n = 84) of the tests performed in the 1st and the 4th week following the implementation of the guidelines. The number of tests performed each week in HCWs increased by at least 20-fold after the implementation of the guidelines. No asymptomatic HCW was tested positive. Screening of asymptomatic HCWs was poorly effective in the context of low circulation of the virus. We suggest giving priority to infection prevention and control measures and screening of symptomatic subjects and asymptomatic contacts.