Background: People with rheumatic diseases may be at increased risk of contracting COVID-19 due to their rheumatic disease or immunosuppressive treatments. It is currently unclear what the COVID-19 disease burden is for these people and whether any of their personal or disease characteristics are associated with contracting COVID-19.

Objectives: To explore the proportion of, and characteristics associated with, contracting COVID-19 in children and young people (CYP) with rheumatic diseases and adults with rheumatic diseases from March 2020 to December 2020 during the COVID-19 pandemic.

Methods: CYP and adults recruited to the international COVID-19 European Patient Registry, a parent-led, online, self-referred prospective cohort recruiting participants from around the globe, were included in current study if enrolled between 20 ^th March 2020 and 30 ^th December 2020. Demographic information was collected at enrolment and rheumatic disease, diagnoses of COVID-19 and lifestyle factors were collected at weekly intervals.

The proportion of CYP and adults diagnosed with COVID-19 were assessed separately. Associations between contraction of COVID-19 at any point over follow-up and participant demographics, rheumatic disease and lifestyle factors at enrolment were assessed descriptively and via Mann-Whitney U-tests, Chi-squared tests and Fisher’s exact tests.

Results: Within 642 CYP and 3646 adults, the majority were female (67%, 89%) and most commonly from the UK (43%, 82%), respectively. The most frequent diagnoses were polyarticular JIA (37%) in the CYP cohort and RA in the adults (63%). Comorbidities were common (45%, 61%) and the majority were taking one or more immunosuppressive therapies (88%, 92%), respectively. At the time of enrolment, 51% and 54% were practising social distancing, respectively.

In both cohorts ~3% contracted COVID-19 at some point during follow-up (n=18 (2.8%) in CYP and n=103 (2.8%) in the adult cohort).

In CYP, those who contracted COVID-19 were older (no COVID, median: 10, IQR: 7, 13, vs COVID, median: 14, IQR: 12, 16, p<0.001) and less often had oligoarticular JIA (no COVID: 31%, COVID: 22%) or polyarticular JIA (No COVID: 38%, COVID: 11%). Systemic JIA (no COVID: 7%, COVID: 11%) and enthesitis-related JIA (no COVID: 5%, COVID: 22%) were more common in those who contracted COVID. No other differences between those with and without COVID-19 were observed with respect to country of residence (p=0.335), gender (p=0.624), control of rheumatic disease (p=0.459), comorbidities (p=0.752), immunosuppressive medication (p=0.713) or social distancing (p=0.729).

In the adult cohort, those contracting COVID-19 were more commonly from Russia (no COVID: 2%, COVID: 14%) and less commonly from the UK (no COVID: 82%, COVID: 71%, p<0.001). There was greater female representation in those that contracted COVID-19 (no COVID: 88%, COVID: 93%, p=0.022). Although there were no differences in overall presence of comorbidity (p=0.923), kidney disease was overrepresented in those that had contracted COVID-19 (no COVID: 2%, COVID: 8%, p<0.001). Finally, there were lower levels of social distancing in those who contracted COVID (no COVID: 54%, COVID: 44%, p=0.047). There were no significant differences in age (p=0.203), BMI (p=0.617), smoking status (p=0.120), rheumatic disease (p=0.181) and its control (p=0.218) or immunosuppressive use (p=0.208) between those who did and did not contract COVID-19 in the adult cohort.

Conclusion: A low proportion of CYP and adults with rheumatic diseases contracted COVID-19 in the 9 months since March 2020. However, given the self-reported nature of the survey and limited testing available across many countries, this study may underestimate the true burden of COVID-19 in the rheumatic disease community. Factors associated with COVID-19 differ between CYP and adults, with age and type of rheumatic disease associated in CYP and gender, kidney comorbidity and social distancing associated in adults.

Acknowledgements: The authors thank all of the participants and families involved in the international COVID-19 European Patient Registry, as well as administrators. We also thank the team of volunteers who helped translate the surveys. We also thank ENCA, PRES and representatives from the international rheumatology community for their expertise and support.

Disclosure of Interests: Stephanie Shoop-Worrall: None declared, Suzanne Verstappen: None declared, Wendy Costello: None declared, Saskya Angevare: None declared, Yosef Uziel: None declared, Carine Wouters: None declared, Nico Wulffraat Speakers bureau: Sobi, Grant/research support from: AbbVie, Richard Beesley: None declared