The first dose of the COVID-19 vaccines from Pfizer/BioNTech and from AstraZeneca Plc produces only weak immune responses in patients being treated with the widely-used rheumatoid arthritis drug infliximab, researchers have found. Infliximab, sold by Johnson & Johnson under the brand name Remicade and available in biosimilar versions, is also approved to treat a range of other autoimmune disorders including plaque psoriasis and ulcerative colitis. In a study of 865 patients receiving regular infusions of infliximab, researchers observed "poor antibody responses" after a single dose of either of the vaccines, which exposes these patients to a potential increased risk of coronavirus infection, according to a paper posted on medRxiv ahead of peer review. The responses improved after the second dose, which suggests patients on infliximab should not delay their second shot, the researchers said. "Until patients receive a second vaccine dose, they should consider that they are not protected from SARS-CoV-2 infection and continue to practice enhanced physical distancing and shielding if appropriate," they advised. Even after two doses, they found that a small subset of patients failed to mount an antibody response. The researchers added that they suspect their findings will apply to other drugs in the class known as TNF inhibitors, including Abbvie's Humira and Amgen's Enbrel, two of the world's top selling medicines. "Antibody testing and adapted vaccine schedules should be considered to protect these at-risk patients," the researchers said.
