Does COVID-19 impact the prevalence of myositis specific antibodies in the Netherlands? A comparative nationwide study.

• Study using nationwide data on myositis specific antibodies (MSA; n = 4962 samples; Euroline myositis line-immunoassay) comparing tests results between a recent pre-COVID-19 year and a year within the COVID-19 pandemic. • Corrected for an increased number of requested tests and corrected for multiple comparisons, three MSAs (PL7, SRP and MDA5) are more prevalent in a year within the COVID-19 pandemic as compared to before the pandemic. • A striking similarity was observed with a finding by others who used a different method comprising seven MSAs out of which the same three MSAs were shown in a cohort of hospitalized patients with SARS-CoV-2. • Our findings substantiate auto-immunity triggered by SARS-CoV-2 on a population level.