Immunosuppressants and COVID-19

Immunosuppressant drugs commonly used for autoimmune diseases such as rheumatoid arthritis, psoriasis, and Crohn’s disease, might, in principle, increase the risk of severe COVID-19 infection and lower vaccines’ efficacy.

Common cold and other upper respiratory tract infections, for example, can be more common in people taking immunosuppressants.

Yet, some such drugs – glucocorticoids, anti-tumour necrosis factors (anti-TNF) and disease-modifying antirheumatic drugs (DMARDs) – are being trialled as potential COVID-19 therapeutics.

Why does this conflicting dichotomy exist? The answer may lie in the difference between the chronic and acute use of these drugs.

A study, published last January in Annals of the Rheumatics Diseases, analysed data from almost 4,000 rheumatology patients who contracted COVID-19. Of these, 10.5% died. Death was associated with known general factors such as older age, male sex and specific comorbidities. But people with more severe rheumatic diseases were more likely to die from COVID-19 than those with low disease activity or in remission. 

Interestingly, most medications used in rheumatic diseases such as DMARDs (the most famous of which is hydroxychloroquine) were not associated with a higher death rate.

The COVID-19 Global Rheumatology Alliance registry found that the use of anti-TNF therapy was associated with a lower rate of hospital admission for COVID-19. But a recent study found that infliximab – an anti-TNF drug prescribed for inflammatory bowel disease – might increase the risk of reinfection.

Chronic glucocorticoid use has been found to increase the hospitalisation rate for COVID-19 in patients with rheumatic disease. Glucocorticoids are also associated with a higher mortality rate in patients with inflammatory bowel disease and chronic obstructive pulmonary disease and asthma patients.

The divergent effect of immunosuppressants exists alongside the divergent effect of the immune system itself on health. Exceptional immunodeficiency is just as harmful as its opposite – excessive immunity is typical of autoimmune disease but also characteristic of systemic inflammatory reactions during acute COVID-19. 

Many severe COVID-19 symptoms are caused by an overreaction of the immune system that leads to severe inflammation. That’s why immunosuppressant drugs are currently being trialled as a potential COVID-19 treatment. To date, the best results have been obtained with acute therapy of glucocorticoids.

In the meantime, the best protection for people who have a compromised immune system remains vaccination.

“We know that the COVID-19 vaccines are suitable for immunosuppressed people as they are not live vaccines,” says Professor Catherine Hill, president of the Australian Rheumatology Association. “But we are waiting for further trials in immunosuppressed patients to ascertain the efficacy of the vaccines.”

As with other immunosuppressed patients, such as cancer patients, the biggest concern around COVID-19 vaccines is whether they will elicit an adequate immune response.

“People who are taking drugs that suppress the immune system may be given the advice to continue avoiding exposure to COVID-19 after they have had the vaccination,” says Hill. “This is because their medications could mean their immune system doesn’t respond as strongly to the vaccine as people who don’t take these drugs.

“This does not mean you should stop your treatment, because this can result in a flare of your condition, which puts you at greater risk from COVID-19.”