24 March 2021
Manuela Callari
Dr Manuela Callari is a Sydney-based freelance science writer who specialises in health and medical stories.
A new study, published today in the BMJ, showed that a commonly prescribed inflammatory bowel disease (IBD) drug called infliximab blunts the immune system response to SARS-CoV2, potentially increasing the risk of reinfection.
Gastroenterologists at the University of Exeter Medical School, UK, recruited almost 7,000 patients with Crohn’s disease and ulcerative colitis from 92 UK hospitals. They found that more than half of the participants treated with infliximab did not have detectable antibodies after SARS-CoV-2 infection.
“Infliximab is a drug used to suppress a person’s immune system,” says Professor Marc Pellegrini, joint head of Infectious Diseases and Immune Defence at Walter and Eliza Hall Institute of Medical Research, who was not involved in the study.
Infliximab treats autoimmune conditions such as rheumatological conditions and inflammatory bowel diseases by suppressing the immune system. “The drug inhibits the activity of a critical immune hormone (cytokine) called TNF [tumour necrosis factor],” Pellegrini says.
Around two million people worldwide are prescribed anti-TNF drugs, which include infliximab. Approximately 1 in 250 people suffer from inflammatory bowel disease in Australia, and almost 75,000 Australians have Crohn’s disease or ulcerative colitis.
“Impaired serological responses to SARS-CoV-2 infection might have important implications for global public health policy,” the authors write. A reduced immune response might lead to an accumulation of the virus in the nose and throat that may act as a reservoir to drive persistent transmission and the evolution of new SARS-CoV-2 variants, the authors explain.
They also suggest that serological testing should be considered to check whether these people develop antibodies after receiving a COVID-19 vaccine.
“It is not surprising that a drug that is used to dampen immunes response and treat autoimmune disease would also dampen immune responses to vaccines,” says Pellegrini.
“People with immune conditions should still be vaccinated. But, along with all people who take anti-TNF treatments or any sort of immune suppressant, they need to be aware that vaccines may not be as effective,” he says.
Pellegrini advises that people with inflammatory bowel disease should continue their regular treatment. But being immunosuppressed puts them at a higher risk of developing severe COVID-19, so they must get their jab, he says.
“Although people who take immunosuppressants may have a reduced response after vaccination, the vaccine may still offer some protection from getting very sick from COVID-19,” Pellegrini says.