Common arthritis drug may weaken COVID vaccine responses, study finds
A small study on patients in New York and Germany found that a quarter of people who take a common drug for inflammatory types of arthritis mounted a weaker immune system response to the Pfizer COVID-19 vaccine than those not taking the medication.
For some, these “weaker” responses involved lower levels of antibodies, but most of the patients taking the drug failed to generate an adequate boost in other key immune system cells, called CD8+ killer T cells, that can help prevent coronavirus infection.
The drug, called methotrexate, is one of the most effective and widely used medications for inflammatory conditions such as rheumatoid arthritis, which affects about 1.3 million Americans; it’s also used to treat some forms of cancer.
However, researchers from the New York University Grossman School of Medicine said the lower immune responses do not mean people with inflammatory disorders are left completely unprotected against severe COVID-19.
The findings suggest “alternate vaccine strategies need to be investigated,” for these people, such as pausing the drug’s use, changing doses or administering booster shots to make up for the weaker responses, according to the study published May 25 in the journal Annals of the Rheumatic Diseases.
“It is most important to state that patients should not be concerned about our study findings as the majority of patients with immune system disorders are responding well to the mRNA vaccines,” study co-first author Dr. Rebecca Haberman, a clinical instructor in the department of medicine at NYU Langone Health, said in a statement. “It is also possible that methotrexate is delaying, rather than preventing, an adequate immune response against COVID-19.”
People with rheumatoid arthritis who take methotrexate are known to experience reduced responses to flu vaccines, so the researchers wanted to learn if similar responses occur after COVID-19 vaccination, which functions differently than flu shots.
Across New York and Germany, the team recruited a total of 245 healthy people and patients with immune-mediated disorders, including rheumatoid arthritis, psoriatic arthritis and psoriasis, who were not taking methotrexate, as well as 45 people with the disorders who were taking methotrexate. All participants received two doses of the Pfizer COVID-19 vaccine.
The researchers took blood samples and analyzed coronavirus antibody levels and activation of CD8+ killer T cells.
Over 90% of healthy people and those taking drugs other than methotrexate to treat their inflammatory disorders “mounted strong antibody responses” and produced adequate activation of CD8+ killer T cells. But about 75% of people taking methotrexate “achieved an adequate [antibody] response,” while the majority did not see “adequate activation” of the special CD8+ killer T cells after vaccination, according to study co-senior author Dr. Jose Scher, an associate professor in the department of medicine at NYU Langone.
“More research is needed to understand why such a significant proportion of people with common immune disorders who take methotrexate have deficiencies in mounting an antibody and cellular response,” Scher said in the statement.
The team is now working to determine a path forward for these patients with weaker responses to COVID-19 vaccination as the pandemic rages on. Some possible courses of action include administering booster shots, reducing methotrexate doses or pausing the drug’s use entirely during the vaccination process.
