Common vaccinations don't raise risk of rheumatoid arthritis, easing fears that they're linked to the inflammatory disease, according to a new study.

Case reports have suggested vaccines, possibly because of their immune-activating adjuvants, could trigger rheumatoid arthritis, a painful autoimmune disease caused by the body's natural defenses attacking and inflaming joints.

But a study published online Tuesday in the Annals of the Rheumatic Diseases found no link between common vaccinations for flu, hepatitis, diphtheria and other illnesses and an increased risk for rheumatoid arthritis. The study also found no increased risk for patients getting vaccinations who had a genetic susceptibility to the disease, or who were smokers. Smoking has long been thought to be a major risk factor for the disease.



Receiving multiple vaccines also didn't up the chances of getting afflicted by the joint disease.

"Our results indicate that immunological provocation of adults with common vaccines in their present form is not a major risk factor for RA," write the authors, led by Camilla Bengtsson, a researcher at the Karolinska Institute in Stockholm, Sweden. "In addition, our results indicate that active immunization does not increase the risk of RA in individuals with established risk factors."

In the epidemiological study, the researchers examined responses of 1,998 patients with rheumatoid arthritis to a questionnaire given shortly after diagnosis, and also responses from 2,252 randomly selected healthy controls matched for age, sex and location, who were mailed the same survey.

Researchers checked whether patients and controls had gotten vaccinations for flu, tetanus, diphtheria, hepatitis A, B, C, polio, pneumococcus and tick-borne encephalitis in the past 5 years. They also noted if they were smokers.

The researchers also obtained blood samples from those in the study to check if they were carriers of HLA-DRB1, a gene believed to raise the risk for rheumatoid arthritis, and whether their arthritis was characterized by the elevated presence of autoantibodies known as antibodies to citrullinated peptide, or ACPA.

After crunching all the numbers, the scientists found no relationship at all between getting one - or a number - of the jabs and coming down with rheumatoid arthritis, either the ACPA-positive or the ACPA-negative variety. In fact, the vaccine for tick-borne encephalitis was associated with a non-significant decreased risk for both forms of the disease.

In addition, no increased risk for the disease was found among those getting a vaccine who were carriers of HLA-DRB1 alleles or smokers.

The authors say that their study doesn't rule out the possibility that rare vaccines, or those gotten much earlier in life, raise the risk for the disease.

"Our study does not exclude the existence of such cases," the authors write, "only that they are relatively rare."