Reactive arthritis after COVID19 vaccination: 17 cases.

OBJECTIVES: The aim of the study is to report a series of 17 cases of ankle bi-arthritis that occurred shortly after Covid-19 RNA vaccination, and to discuss the potential role of these vaccines in the pathogenesis of this rheumatological manifestation. METHODS: All patients were examined in the same department and received a full work-up to investigate the usual causes of ankle bi-arthritis. No rheumatic inflammatory disease occurred after 9 months follow -up. A post vaccination serological follow-up in search of anti-Spike antibodies was request for all patients. RESULTS: All patients recovered with low dose of prednisolone within <2 months, except one who could not be weaned off corticosteroids. The level of antibodies found was very high in all patients. CONCLUSION: The ankle bi-arthritis occurrence chronology, the follow-up, and the similar clinical presentation might suggest a pathogenic role of RNA vaccination.

Nationwide Harmonization Effort for Semi-Quantitative Reporting of SARS-CoV-2 PCR Test Results in Belgium.

From early 2020, a high demand for SARS-CoV-2 tests was driven by several testing indications, including asymptomatic cases, resulting in the massive roll-out of PCR assays to combat the pandemic. Considering the dynamic of viral shedding during the course of infection, the demand to report cycle threshold (Ct) values rapidly emerged. As Ct values can be affected by a number of factors, we considered that harmonization of semi-quantitative PCR results across laboratories would avoid potential divergent interpretations, particularly in the absence of clinical or serological information. A proposal to harmonize reporting of test results was drafted by the National Reference Centre (NRC) UZ/KU Leuven, distinguishing four categories of positivity based on RNA copies/mL. Pre-quantified control material was shipped to 124 laboratories with instructions to setup a standard curve to define thresholds per assay. For each assay, the mean Ct value and corresponding standard deviation was calculated per target gene, for the three concentrations (107, 105 and 103 copies/mL) that determine the classification. The results of 17 assays are summarized. This harmonization effort allowed to ensure that all Belgian laboratories would report positive PCR results in the same semi-quantitative manner to clinicians and to the national database which feeds contact tracing interventions.