Study findings updated . AI-assisted evidence summary, not individual medical advice or a clinician endorsement.
THE SHORT VERSION
What’s worth knowing.
The key findings, what they mean, and the context that matters.
THE HEADLINE TAKEAWAY25% higher riskof new autoimmune rheumatic disease after COVID vs no infection (hazard ratio)
COVID was linked to new autoimmune rheumatic diseases, more than flu.
Among Korean adults, people who had COVID had a 25% higher risk (hazard ratio 1.25) of a new autoimmune rheumatic disease diagnosis beyond the first 30 days than matched uninfected people. Their risk was also 30% higher than in people who had flu. Risk was higher when COVID was more severe, and Japanese data showed similar patterns.
COVID was linked to more new cases than flu, hinting it may affect the immune system in a distinct way. New joint pain, rashes or dry eyes after COVID are worth mentioning to a doctor. An insurance-claims study, so diagnoses rely on billing codes and pandemic-era doctor visits; it shows a link, not proof that COVID causes these diseases.
See the evidence
A matched cohort study of national insurance records for about 10 million Korean and 12 million Japanese adults, comparing people with COVID in 2020–2021 to uninfected and flu-infected people.
From the study: “beyond the first 30 days after infection, patients with COVID-19 were at increased risk for incident AIRD compared with uninfected patients (adjusted hazard ratio, 1.25 [95% CI, 1.18 to 1.31])”
25% higher risk
Kim MS et al. Long-Term Autoimmune Inflammatory Rheumatic Outcomes of COVID-19 : A Binational Cohort Study. Annals of internal medicine. 2024.
Most targeted immune drugs were not linked to more COVID deaths.
No added death riskon most targeted drugs vs standard drugs like methotrexate; rituximab the exception
Among English adults with inflammatory joint, skin or bowel diseases, those on targeted drugs like TNF or JAK inhibitors were no more likely to die of COVID than those on standard drugs like methotrexate. Rituximab, which wipes out antibody-making B cells, was linked to more COVID deaths (hazard ratio 1.68).
People with these diseases had more COVID deaths overall, and many feared their biologic was to blame. This study points the extra danger at rituximab rather than most targeted drugs. Observational data from 2020, before vaccines and antivirals; sicker patients may get different drugs, and COVID outcomes have improved greatly since.
See the evidence
A national health-records study of more than 17 million adults in England, more than 1 million with inflammatory diseases, tracking COVID outcomes from March to September 2020.
From the study: “Our observation that adults on targeted therapies (except rituximab) do not have an increased risk of COVID-19 related death is consistent with data from international registries.”
No added death risk
MacKenna B et al. Risk of severe COVID-19 outcomes associated with immune-mediated inflammatory diseases and immune-modifying therapies: a nationwide cohort study in the OpenSAFELY platform. The Lancet. Rheumatology. 2022.
From the study: “Rituximab was associated with increased COVID-19-related death (HR 1·68, 95% CI 1·11-2·56)”
No added death risk
MacKenna B et al. Risk of severe COVID-19 outcomes associated with immune-mediated inflammatory diseases and immune-modifying therapies: a nationwide cohort study in the OpenSAFELY platform. The Lancet. Rheumatology. 2022.
From the study: “COVID-19 deaths and hospital admissions were higher in people with immune-mediated inflammatory diseases.”
No added death risk
MacKenna B et al. Risk of severe COVID-19 outcomes associated with immune-mediated inflammatory diseases and immune-modifying therapies: a nationwide cohort study in the OpenSAFELY platform. The Lancet. Rheumatology. 2022.
Paxlovid was linked to less hospitalization or death on rituximab-type drugs.
44% lower riskof hospitalization or death with Paxlovid on rituximab-type drugs (hazard ratio)
Among adults with immune-mediated inflammatory diseases taking rituximab or ocrelizumab (drugs that wipe out antibody-making B cells) who caught COVID, 4.4% of those treated early with nirmatrelvir/ritonavir (Paxlovid) were hospitalized or died within 21 days, versus 9.2% of untreated patients: a 44% lower risk after adjustment.
People on these drugs often make few vaccine antibodies, so they stay at high risk. Here an oral antiviral was linked to better outcomes in the Omicron era; molnupiravir's result was not statistically clear. Records from one US health system, not a randomized trial; treated and untreated patients may differ in ways statistical adjustment cannot fully fix.
See the evidence
A records study designed to mimic a trial, using Cleveland Clinic data on 876 adults on rituximab or ocrelizumab who tested positive between December 2021 and June 2025.
From the study: “In the nirmatrelvir/ritonavir cohort, 18 (4.4%) of treated versus 43 (9.2%) of untreated patients were hospitalized or died within 21 days.”
44% lower risk
Calabrese C et al. Effectiveness of Nirmatrelvir/Ritonavir or Molnupiravir Use in Immunocompromised Patients on B-Cell-Depleting Therapy With COVID-19: A Target Trial Emulation Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2026.
From the study: “After weighting, nirmatrelvir/ritonavir reduced the hazard by 44% (hazard ratio [HR], 0.56; 95% confidence interval [CI], 0.31-0.99).”
44% lower risk
Calabrese C et al. Effectiveness of Nirmatrelvir/Ritonavir or Molnupiravir Use in Immunocompromised Patients on B-Cell-Depleting Therapy With COVID-19: A Target Trial Emulation Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2026.
From the study: “Molnupiravir showed a nonsignificant trend toward benefit.”
44% lower risk
Calabrese C et al. Effectiveness of Nirmatrelvir/Ritonavir or Molnupiravir Use in Immunocompromised Patients on B-Cell-Depleting Therapy With COVID-19: A Target Trial Emulation Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2026.
People with autoimmune rheumatic diseases were diagnosed with long COVID more often.
56% higher riskof diagnosed long COVID in people with autoimmune rheumatic disease (hazard ratio)
Among US adults with a first COVID infection, 2.8% of people with autoimmune rheumatic diseases such as lupus or Sjögren's were diagnosed with long COVID, versus 1.5% of matched people without them: a 56% higher risk (hazard ratio 1.56). Use of rituximab or steroids, more severe COVID, obesity and lung disease were linked to higher risk.
Long COVID can be hard to tell apart from the fatigue and pain of rheumatic disease. This large US dataset suggests the added risk is real and flags rituximab and steroid users as groups to watch. Long COVID was counted only when a diagnosis code or clinic visit was recorded, so unrecognised cases are missed and doctors may label the two groups differently.
See the evidence
A US national health-records study (N3C) of 187,106 matched adults first infected between September 2021 and December 2023, followed through December 2024.
From the study: “In the matched cohort of 187,106 patients, Long COVID occurred in 2.8% of AIRD patients and 1.5% among non-AIRD patients.”
56% higher risk
Singh, Namrata et al.. Higher risk of Long COVID among patients with autoimmune rheumatic diseases and immunomodulatory therapy: a retrospective cohort analysis of national US data.. Arthritis & rheumatology (Hoboken, N.J.). 2026.
From the study: “In multivariable analyses, AIRD was associated with an increased risk of Long COVID compared with non-AIRD patients (aHR 1.56, 95% CI 1.45-1.67).”
56% higher risk
Singh, Namrata et al.. Higher risk of Long COVID among patients with autoimmune rheumatic diseases and immunomodulatory therapy: a retrospective cohort analysis of national US data.. Arthritis & rheumatology (Hoboken, N.J.). 2026.
From the study: “higher acute COVID-19 severity, pulmonary disease, obesity, and exposure to rituximab or glucocorticoids were associated with an increased risk of Long COVID”
56% higher risk
Singh, Namrata et al.. Higher risk of Long COVID among patients with autoimmune rheumatic diseases and immunomodulatory therapy: a retrospective cohort analysis of national US data.. Arthritis & rheumatology (Hoboken, N.J.). 2026.
Pausing methotrexate two weeks after a booster doubled antibody levels.
2.19× the antibodiesin people who paused methotrexate for 2 weeks after a booster; flares rose too
In a UK randomized trial of adults with inflammatory conditions such as rheumatoid arthritis or psoriasis taking weekly methotrexate, pausing it for 2 weeks after a COVID booster led to antibody levels 2.19 times higher than continuing it. The trade-off: 71% in the pause group reported at least one flare over 12 weeks, versus 45% who kept taking it.
Methotrexate, the most common rheumatic drug, blunts vaccine responses. A short pause boosted antibodies, but the trial did not test whether that prevents infections, and more flares were the cost. Antibody level is a lab marker, not proof of fewer infections, and the trial was open-label, so knowing one's group may have shaped flare reports.
See the evidence
A randomized trial at 26 UK hospitals that assigned 254 adults on low-dose weekly methotrexate to pause it for 2 weeks or continue after a COVID booster, 2021–2022.
From the study: “with a geometric mean ratio (GMR) of 2·19”
2.19× the antibodies
Abhishek A et al. Effect of a 2-week interruption in methotrexate treatment versus continued treatment on COVID-19 booster vaccine immunity in adults with inflammatory conditions (VROOM study): a randomised, open label, superiority trial. The Lancet. Respiratory medicine. 2022.
From the study: “A 2-week interruption of methotrexate treatment for people with immune-mediated inflammatory diseases resulted in enhanced boosting of antibody responses after COVID-19 vaccination.”
2.19× the antibodies
Abhishek A et al. Effect of a 2-week interruption in methotrexate treatment versus continued treatment on COVID-19 booster vaccine immunity in adults with inflammatory conditions (VROOM study): a randomised, open label, superiority trial. The Lancet. Respiratory medicine. 2022.
From the study: “over the 12-week follow-up period (85 [71%] of 120 vs 56 [45%] of 125; odds ratio 2·83 [95% CI 1·64–4·88])”
2.19× the antibodies
Abhishek A et al. Effect of a 2-week interruption in methotrexate treatment versus continued treatment on COVID-19 booster vaccine immunity in adults with inflammatory conditions (VROOM study): a randomised, open label, superiority trial. The Lancet. Respiratory medicine. 2022.
A rare inflammatory syndrome can hit adults weeks after COVID.
About 4 weeks latera rare, severe inflammatory syndrome (MIS-A) can strike adults after infection
In reported adult cases of MIS-A, a rare reaction that inflames many organs at once, illness typically began about 4 weeks after COVID. 58% had no underlying health condition, yet 57% needed intensive care and 7% died.
It can follow a mild or unnoticed infection, so fever, low blood pressure, heart problems or diarrhea weeks later may not be linked to COVID. Knowing the pattern can speed diagnosis. Pieced together from case reports and CDC surveillance, so it shows what reported cases looked like, not how common MIS-A is or who is most at risk.
See the evidence
A systematic review of 221 adult MIS-A cases from published reports and CDC surveillance, mostly from the US, covering May 2020 to May 2021.
From the study: “MIS-A is a serious hyperinflammatory condition that presents approximately 4 weeks after onset of acute COVID-19 with extrapulmonary multiorgan dysfunction”
About 4 weeks later
Patel P et al. Clinical Characteristics of Multisystem Inflammatory Syndrome in Adults: A Systematic Review. JAMA network open. 2021.
From the study: “115 of 201 patients (57%) were admitted to the intensive care unit; 101 of 213 (47%) required respiratory support, and 15 of 220 (7%) died.”
About 4 weeks later
Patel P et al. Clinical Characteristics of Multisystem Inflammatory Syndrome in Adults: A Systematic Review. JAMA network open. 2021.
Severe COVID became far less common in people with autoimmune diseases.
1 in 7 cases severein the Omicron wave, down from 46% in early 2020; severe = hospital stay or death
Among patients with systemic autoimmune rheumatic diseases who caught COVID at Mass General Brigham, 46% of cases were severe (hospitalization or death) in the early COVID-19 period of 2020, versus 15% in the initial Omicron wave. Unvaccinated patients were overrepresented among severe cases.
Much of the alarming early data on rheumatic patients came from 2020. The authors suggest better prevention, diagnosis and treatment may explain much of the drop. Records from one health system; wider testing later in the pandemic may have caught more mild cases, which could make the decline look bigger.
See the evidence
A retrospective records study of 1,449 patients with systemic autoimmune rheumatic diseases and confirmed COVID at Mass General Brigham, March 2020 to January 2022.
From the study: “46% of cases were severe in the early COVID-19 period (1 March 2020-30 June 2020) vs 15% in the initial Omicron wave”
1 in 7 cases severe
Kawano Y et al. Temporal trends in COVID-19 outcomes among patients with systemic autoimmune rheumatic diseases: from the first wave through the initial Omicron wave. Annals of the rheumatic diseases. 2022.
From the study: “A higher proportion of those unvaccinated were severe compared with not severe cases (78% vs 60%).”
1 in 7 cases severe
Kawano Y et al. Temporal trends in COVID-19 outcomes among patients with systemic autoimmune rheumatic diseases: from the first wave through the initial Omicron wave. Annals of the rheumatic diseases. 2022.
Rheumatic disease flares after COVID vaccination were uncommon and rarely severe.
1 in 23 had a flareof their rheumatic disease after COVID vaccination; 0.6% were severe
In a doctor-reported registry of people with inflammatory or autoimmune rheumatic diseases who got COVID vaccines, flares of their disease were reported in 4.4% of cases; 0.6% were severe and 1.5% led to medication changes. Serious health problems after vaccination were reported in 0.4% of these patients.
Fear of a flare keeps some people with lupus or arthritis from getting vaccinated. These reports suggest flares were uncommon, mostly mild and rarely required changing treatment. Doctors chose which patients to report and there was no unvaccinated comparison group, so true flare rates could be higher or lower.
See the evidence
A physician-reported registry of 5,121 vaccinated people with rheumatic and musculoskeletal diseases in 30 countries, February to July 2021.
From the study: “I-RMD flares were reported in 4.4% of cases (0.6% severe), 1.5% resulting in medication changes.”
1 in 23 had a flare
Machado PM et al. Safety of vaccination against SARS-CoV-2 in people with rheumatic and musculoskeletal diseases: results from the EULAR Coronavirus Vaccine (COVAX) physician-reported registry. Annals of the rheumatic diseases. 2022.
From the study: “AEs were reported in 37% of cases (37% I-RMD, 40% NI-RMD), serious AEs in 0.5% (0.4% I-RMD, 1.9% NI-RMD).”
1 in 23 had a flare
Machado PM et al. Safety of vaccination against SARS-CoV-2 in people with rheumatic and musculoskeletal diseases: results from the EULAR Coronavirus Vaccine (COVAX) physician-reported registry. Annals of the rheumatic diseases. 2022.
Infected lupus patients had higher hospitalization odds than healthy controls
aOR 6.13
Infected participants with systemic lupus erythematosus had higher adjusted odds of COVID-19 hospitalization than infected healthy controls (aOR 6.13).
Cross-sectional Chinese study conducted January–February 2023; 95% CI 3.06–12.27. Adjustment included age, sex, comorbidities and vaccination. Odds are not absolute risk or proof of causation.
Study details & original results
Zang, Sitian et al.. Mycophenolate mofetil associates with COVID-19 hospitalization in patients with systemic lupus erythematosus: a nationwide population-based study from China.. Clinical Rheumatology. 2026.
Adjusted odds of COVID-19 hospitalization in infected Chinese participants with systemic lupus erythematosus versus infected healthy controls, from a cross-sectional study conducted January–February 2023; adjusted for age, sex, comorbidities and vaccination status.
Dates show when findings were added here, not when papers were published. Study populations and comparisons differ.
WHEN YOU WANT TO GO DEEPERSee all 1 findingsOriginal results, comparisons and study details.
1 of 1 source groupsFindings stay together with their study.
SOURCE 021 finding
Zang, Sitian et al.. Mycophenolate mofetil associates with COVID-19 hospitalization in patients with systemic lupus erythematosus: a nationwide population-based study from China.. Clinical Rheumatology. 2026.
Adjusted odds of COVID-19 hospitalization in infected Chinese participants with systemic lupus erythematosus versus infected healthy controls, from a cross-sectional study conducted January–February 2023; adjusted for age, sex, comorbidities and vaccination status.
Browse the 9 original sourcesThe complete bibliography behind this monitor.
[1]
Singh, Namrata et al.. Higher risk of Long COVID among patients with autoimmune rheumatic diseases and immunomodulatory therapy: a retrospective cohort analysis of national US data.. Arthritis & rheumatology (Hoboken, N.J.). 2026.
Zang, Sitian et al.. Mycophenolate mofetil associates with COVID-19 hospitalization in patients with systemic lupus erythematosus: a nationwide population-based study from China.. Clinical Rheumatology. 2026.
MacKenna B et al. Risk of severe COVID-19 outcomes associated with immune-mediated inflammatory diseases and immune-modifying therapies: a nationwide cohort study in the OpenSAFELY platform. The Lancet. Rheumatology. 2022.
Calabrese C et al. Effectiveness of Nirmatrelvir/Ritonavir or Molnupiravir Use in Immunocompromised Patients on B-Cell-Depleting Therapy With COVID-19: A Target Trial Emulation Study. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 2026.
Abhishek A et al. Effect of a 2-week interruption in methotrexate treatment versus continued treatment on COVID-19 booster vaccine immunity in adults with inflammatory conditions (VROOM study): a randomised, open label, superiority trial. The Lancet. Respiratory medicine. 2022.
Kawano Y et al. Temporal trends in COVID-19 outcomes among patients with systemic autoimmune rheumatic diseases: from the first wave through the initial Omicron wave. Annals of the rheumatic diseases. 2022.
Machado PM et al. Safety of vaccination against SARS-CoV-2 in people with rheumatic and musculoskeletal diseases: results from the EULAR Coronavirus Vaccine (COVAX) physician-reported registry. Annals of the rheumatic diseases. 2022.
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