The research found that people using the biologic drug infliximab (Remicade), which belongs to the anti-tumor necrosis factor (anti-TNF) class of drugs, had significantly lower antibody concentrations after their first dose of a COVID-19 vaccine than people using an alternative biologic called vedolizumab (Entyvio). This drug has a different mode of action and belongs to the gut-specific integrin receptor antagonist class of drugs.
However, in a subgroup of people who had previously had SARS-CoV-2, and in a few people who had already had a second vaccine dose, the antibody response increased significantly.
Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.
The findings have important implications for the many people around the world who are using anti-TNF drugs such as Remicade. Study co-author Dr. Nick Powell, of Imperial College London in the United Kingdom, told Medical News Today:
“Anti-TNF drugs are not just used for [people with] IBD, but also for millions of other [people] with arthritis, psoriasis, and other inflammatory diseases. Our data suggest that prompt access to a second dose of vaccine might be a better option for immunosuppressed [people].”
Vaccines protect people from infectious diseases by stimulating the immune system to produce antibodies. For a vaccine to be effective, it must trigger sufficient antibodies to target the virus and prevent subsequent infections.
Anti-TNF drugs are effective treatments for immune-mediated inflammatory conditions such as IBD. They work by “tuning down” inflammation in the body, explains Prof. Duncan Richards, from the University of Oxford, also in the U.K. Prof. Richards was not involved in the study.
However, this tuning down of the immune system might also reduce the immune response to the vaccine.
“Many drugs in this group are associated with a small increased risk of infection, and a reduced antibody response to vaccines has also been observed before,” Prof. Richards told MNT.
“The key […] is the benefit-risk — these drugs are important to control these severe inflammatory conditions, and, overall, the benefit-risk is considered positive because the risks are small.”
After a single dose of either the Oxford-AstraZeneca or the Pfizer-BioNTech COVID-19 vaccine, antibody concentrations were significantly lower in the 865 people using Remicade than in the 428 people using Entyvio.
Only 31% of people exclusively using Remicade produced enough SARS-COV-2 antibodies to meet the threshold for the vaccine to be considered effective. This was in comparison with around two-thirds of those using only Entyvio.
Antibody levels were even lower after one vaccine dose in people using Remicade in combination with immunomodulatory drugs such as azathioprine or methotrexate. Only 23% of these people generated adequate levels of antibodies.
Reassuringly, the antibody response appears to improve in people using Remicade after a second exposure to either the virus or a vaccine.
The study found much higher antibody levels in people who had already had a SARS-CoV-2 infection before vaccination and in 27 people who had received two vaccine doses.
“One potential consequence of our observations is that [people with IBD] will not be fully protected after a single dose of vaccine, [which] emphasizes the importance of immunosuppressed [people] taking up their second vaccine dose when offered,” said Dr. Powell.
“Booster doses are very important, and it seems, at least for antibody production, a single dose isn’t quite enough to get robust antibody responses.”
– Dr. Nick Powell
Dr. Powell also suggests that people using anti-TNF drugs continue to follow strict physical distancing measures and shield if appropriate.
Many countries, including the U.K., have chosen to delay second COVID-19 vaccine doses to achieve wider coverage of a lower level of immunity across more of the population.
The study authors recommend that healthcare professionals prioritize people undergoing anti-TNF therapy for earlier second doses.
A small group of people in the study did not mount an antibody response, even after two exposures to the virus.
However, Prof. Richards explained that having a small number of people who do not respond to vaccination is expected.
“You will always get some of these,” he told MNT. “It will be important to know if this rate is higher than seen overall.”
One limitation of the new study is that it only considered antibody responses — not risk of infection after vaccination.
“It is important to recognize that antibody responses are not the only form of immune protection from the virus, and other arms of the immune system may not be so severely affected by anti-TNFs,” said Dr. Powell.
“We are actively looking to see whether immune responses mediated by T cells, one of the other key immune cells responsible for defending the body from viral infection, is also affected.”
“Antibody responses are only a proxy measure of success or failure of a vaccine, and the real proof of the pudding is whether the vaccine reduces infection risk — as they have done very successfully in clinical trials.”
For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.