Commonly prescribed drug for IBD blunts COVID-19 vaccine response

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People taking a commonly prescribed drug for inflammatory bowel disease (IBD) should not assume they are protected after a first dose of COVID-19 vaccine, after a large-scale study found that many had poor antibody responses.

Research measured antibody responses after vaccination with the Pfizer / BioNTech or Oxford / AstraZeneca COVID-19 vaccine in 865 people treated with infliximab, an anti-tumor necrosis factor (anti-TNF) biologic drug, prescribed to approximately two million people. people around the world. Anti-TNF drugs are effective treatments for immune-mediated inflammatory diseases, but by suppressing the immune system, they can reduce the effectiveness of the vaccine and increase the risk of serious infection.

Led by the University of Exeter and the Royal Devon and Exeter NHS Foundation Trust, and published in GUT, the article is a result of the CLARITY study funded by NIHR and Crohn’s and Colitis UK. Research found that people treated with infliximab had significantly lower antibody levels than 428 people on the alternative treatment, vedolizumab.

Vaccines work by stimulating the immune system to produce antibodies that protect people from future infection. For a vaccine to be effective, it must trigger a sufficient number of antibodies targeting the virus to prevent further infection.

After a single dose of vaccine, only about a third of participants (103 of 328) treated exclusively with infliximab generated adequate levels of antibodies against the virus for the vaccine to be considered effective. In participants taking infliximab concomitantly with immunomodulatory drugs, such as azathioprine or methotrexate, antibody levels were even lower after a single dose of the vaccine; only 125 out of 537 crossed the threshold for a positive antibody test.

However, in a subgroup of people who had previously been infected with COVID-19, and also in the few patients studied who had already received a second dose of the vaccine, the antibody responses elicited by the vaccine increased significantly, indicating an effective response after two exposures. Based on these observations, the researchers conclude that people taking anti-TNF drugs should be prioritized for a second vaccination.

The CLARITY study recruited 6,935 Crohn’s disease and ulcerative colitis patients from 92 UK hospitals between September and December 2020, to study the impact of these drugs on COVID-19 susceptibility and protective immunity that follows infection or vaccination. Previously, the study found that infliximab weakened the immune system against COVID-19 infection, potentially increasing the risk of re-infection.

Dr Tariq Ahmad, head of the CLARITY study, said the current findings have important implications for people being treated with anti-TNF therapy, especially those also being treated with an immunomodulator. He said: “Poor antibody responses to a single dose of vaccine put these patients at a potential increased risk of COVID-19. However, we found much higher antibody levels in people vaccinated after a previous COVID-19 infection and in the small number of patients. who had received two doses of the vaccine, suggesting that all patients receiving these drugs should be prioritized for second doses at the optimal time. “

500,000 people across the UK are living with inflammatory bowel disease (IBD) of which ulcerative colitis and Crohn’s disease are the two main forms. Symptoms include urgent and frequent bloody diarrhea, weight loss, pain, and extreme fatigue. At the start of the COVID-19 pandemic, the British government indicated that patients taking anti-TNF drugs could be at an increased risk of complications from the coronavirus. All have been urged to follow strict social distancing measures, and some, depending on the severity of their condition, have been urged to protect themselves.

While we know this has been an incredibly difficult time for people with IBD, our research indicates that people treated with infliximab should consider that they are not protected against COVID-19 until they do. have not received both doses of a vaccine and should continue to practice in an improved manner. physical distancing and protection, where applicable. “

Dr Nick Powell, co-author, Imperial College London

In the study, a small subset of patients showed no antibody response even after two exposures to COVID-19. Co-author Dr James Goodhand, University of Exeter, said: “Our results come as European countries choose to delay the second dose of vaccine. We recommend prioritizing second doses to patients. taking anti-TNF drugs, which will remain high risk after their first dose. More data is needed to determine whether we should test antibody levels after two doses to identify the small number of patients who do not have responded well to vaccination.

The study also found evidence that antibody responses were lower in current smokers and participants aged 60 or older, but higher in non-white participants. These results warrant further investigation in larger studies before definitive conclusions can be drawn.

Sarah Sleet, Managing Director of Crohn’s & Colitis UK, said: “This is the first strong evidence that people with Crohn’s and colitis – who may need to take specific drugs to suppress their immune system – do not do not develop the expected antibodies after their first dose vaccination, although a second dose improves antibody levels. With 1 in 5 people not developing antibodies even after 2 doses, these people will be desperately worried about being at risk of catch COVID-19 and develop more severe disease by a time when the shielding is finished. We need urgent research on the optimal time between the first and second jab, and the need to be a priority for any jab recall this fall. “


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