Nearly 294,000 children under the age of 18 are affected by juvenile arthritis. The disease can affect four or more joints in the bodies of these children, limiting their range of motion and everyday activities. It can also cause inflammation of these joints, which can lead to high fevers, rashes, or eye infections. The cause of the development of this noncontagious disorder is not yet known for both adults and children.

Rheumatoid arthritis is an autoimmune disease. This means that the body's immune system is working to fight off its own cells because it understands them as disease-causing agents. This leads to immune dysfunction in two ways. First, the immune system is attacking one's own cells, and in the case of arthritis and many other disorders, causes serious issues with the parts of the body it is attacking, like the joints. Secondly, it stops the immune system from working properly and attacking the actual invaders and preventing infections.

A juvenile arthritis patient's compromised immune system can prove difficult when it comes to immunizations. Immunizations, or vaccines along with their boosters, provide the body with potential viruses that can infect it. They provide a small amount so that the body can build resistance to the viruses and not become affected should a real infection occur. However, given a suppressed immune system, a vaccine or its booster could be harmful, as the immune system may not be able to attack it and the virus could end up affecting the entire body.

The measles, mumps, and rubella (MMR) vaccine is given to children worldwide, protecting against three viral infections that are very likely to make children sick. These three ailments are viral infections that can even lead to death if contracted, as they can cause unmanageable fevers and rashes. Mumps and rubella, when real infections occur, affect joints like the jaw. In a previous, but small, study of juvenile arthritis, the safety of MMR vaccine was called into question, as rubella has the capacity to induce arthritis in children. This is likely because it suppresses the immune system even after its symptoms have subsided, as this is how viruses operate. Viruses integrate themselves into a person's DNA and can cause other flare ups of infection even after symptoms disappear.

It was thought for some time that this vaccine could worsen juvenile arthritis, as introduction of these viruses into an already immunocompromised person could just make them sicker. In a new study, however, researchers have found that this is not quite the case.

The study was performed on 137 children with juvenile arthritis and were aged four to nine. Half of them were given booster shots for MMR and half were not. The researchers found that those receiving a booster shot, indicating that they had been vaccinated before, did not have worsened symptoms for up to one year after the booster shot was administered. Instead, their immune systems reacted positively to the booster shot and formed the necessary antibodies against mumps, measles, and rubella. Ninety-seven percent of the booster shot group made new immune response cells against measles, 78 percent made new immune cells against the mumps, and 90 percent made immune cells to fight against rubella. This is noteworthy, as the once completely immunodeficient juvenile arthritis patient is actually capable of having his or her immune system make new cells to attack foreign disease-causing agents when a small infection, like mumps or measles, is introduced to the body.

The disease activity of their arthritis remained unchanged after the booster shots were given to them. Across the groups that did and did not receive the MMR booster shot, none of the children experienced a lessening or worsening of symptoms. This indicates that treatment with the vaccine and booster shot does not affect arthritis at all.

However, more work must be done to determine whether drug interactions between arthritis medications and the MMR booster shot may become worrisome. In the study, the children with arthritis were either taking methotrexate, a drug that reduces severity of arthritis by preventing cell growth, or biologics, which work at the level of the immune system to stop it from attacking joints and other host tissues. In the study, patients using biologics were a minority; there were only nine of them, but none of them showed adverse effects toward vaccination. However, biologics are being used more frequently, and more ought to be done to understand the drug interaction if methotrexate will be used less frequently.

Prevention of infection by MMR vaccination is recommended to all, as it can mean the difference of manageable arthritis and death by a viral infection. Those with immune system deficiencies, like children affected by juvenile arthritis, should take every precaution to prevent other diseases from infecting them as well. The researchers saw studies of larger groups on different medications ought to be performed, but it is clear form this study that MMR vaccines do not worsen arthritis as once thought.

Source: Heijstek MW, Kamphuis S, Armbrust W, et al. Effects of the Live Attenuated Measles-Mumps-Rubella Booster Vaccination on Disease Activity in Patients With Juvenile Idiopathic Arthritis. JAMA. 2013.