Arthritis drugs may impair response to flu vaccine

Drugs known as TNF inhibitors used to treat rheumatoid arthritis modestly impair the immune response to influenza vaccination, which may render people who use these drugs more vulnerable to catching the flu, according to a new study.

The study team emphasizes, however, that most people who take these drugs are able to achieve adequate protection from the flu by getting a flu shot.

“Influenza vaccination is still effective in patients treated with anti-TNF,” Dr. Luc B. S. Gelinck from Leiden University Medical Center, the Netherlands, told Reuters Health. Examples of anti-TNF drugs are Enbrel, Remicade and Humira.

Gelinck and colleagues compared the immune response after influenza vaccination in 112 patients treated with immunosuppressive therapy, including anti-TNF agents; 48 matched patients not treated with anti-TNF agents, and 18 healthy controls.

The flu vaccine works by causing people to develop antibodies to the influenza strains contained in the vaccine, which will protect them when they are exposed to the flu.

Four weeks after flu vaccination, the levels of protective antibodies were significantly lower for the anti-TNF group than for the no anti-TNF group. Both immunosuppressive therapy groups had lower levels of protective antibodies than did healthy controls.

Despite these differences, though, protection rates 4 weeks after vaccination were high in all groups and did not differ significantly.

“This endorses the current guidelines for a single, annual influenza vaccination of these patients, including those treated with anti-TNF,” the researchers conclude.

Anti-TNF drugs do, however, “lower the response on vaccination,” Gelinck said. He suggests vaccinating patients before they start these medications, “if possible.”

SOURCE: Annals of the Rheumatic Diseases, May 2008.