Two thirds of the cohort (67.6%) took infliximab, while the remainder took vedolizumab. Patients’ median age was 39 years.
The study found that people with COVID-19 infections who also used the inflammatory bowel disease (IBD) drug infliximab had significantly fewer detectable antibodies than those who used vedolizumab, which treats IBD without the immune suppression, according to a study published in the journal Gut.
Lower antibody presence was seen in those who took infliximab, raising the researchers’ concerns about reinfection risk. Researchers note that 3.4% of the infliximab-treated group had SARS-CoV-2 seroprevalence, compared to 6.0% of the vedolizumab-treated group did. Those who were on additional immunomodulators such as thiopurines and methotrexate also had a reduced likelihood of being seropositive.
Of people with confirmed COVID-19 infections, only 48.0% of the 81 treated with infliximab demonstrated seroconversion, compared with 83.3% of the 36 on vedolizumab.
An impaired immune response may boost susceptibility to recurrent COVID-19 and may drive the evolution of new variants of SARS-CoV-2, warn the researchers. However, they are encouraging people to continue to take their medication as the overall COVID-19 risk remains low. Careful monitoring of patients with IBD treated with infliximab, who have been vaccinated against COVD-19, will be needed to ensure they mount a strong enough antibody response to ward off the infection, they advise.
CLARITY study lead, Professor Tariq Ahmad, of the University of Exeter Medical School, said:
“The poor antibody responses observed in patients treated with infliximab raise the possibility that some patients may not develop protective immunity after COVID-19 infection, and might be at increased risk of reinfection. What we don’t yet know is how the use of anti-TNF drugs will impact antibody responses to vaccination.”
The burden of inflammatory bowel disease is rising globally. The incidence of IBD is approximately 0.5-24.5 cases per 100,000 person-years for ulcerative colitis and 0.1-16 cases per 100,000 person-years for Crohn disease. Overall, the prevalence for IBD is 396 cases per 100,000 persons annually.
Around two million people worldwide are prescribed anti-tumour necrosis factor (anti-TNF) drugs, which include infliximab. Anti-TNF drugs are effective treatments for immune-mediated inflammatory diseases, but by suppressing the immune system, they can reduce vaccine effectiveness and increase the risk of serious infection.
Melvin is a curious lifelong learner. He studied biology, medicine, health economics, infectious diseases, clinical development, and public policy. He writes about global health, vaccines, outbreaks, and pathogens.