Your Good Health: Immunotherapy might reduce effectiveness of vaccines

dr_keith_roach_with_bkg.jpgDear Dr. Roach: I am currently on rituximab immunotherapy. I have had my first Moderna vaccine, and my second shot is in four weeks. My oncologist is not sure how the rituximab affects the effectiveness of the vaccine. Can you explain how people on immunotherapy should most effectively take the vaccine while undergoing treatment? My next immunotherapy is three days after my second Moderna shot.


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Rituximab is a monoclonal antibody directed against B cells, the cells responsible for making antibodies. It is used for cancer treatment of B cell-related malignancies, such as non-Hodgkin’s lymphomas and some leukemias. It is also used for autoimmune disorders such as rheumatoid arthritis and autoimmune skin diseases.

Because rituximab directly targets B cells, it is known to reduce effectiveness of vaccines, particularly polysaccharide vaccines such as Pneumovax, but it also blunts the response to the flu shot. When possible, it’s recommended to give vaccines either before starting rituximab or at least six months after completing rituximab treatment.

Your oncologist doesn’t know the effect of rituximab on the new COVID-19 vaccines because nobody does: They haven’t been studied at all. While it is very likely that the vaccine is safe, it is probable that the vaccine will not be as effective in a person taking rituximab. I would speculate that it would be reasonable to consider revaccination six months after completing rituximab. Perhaps by then we will have additional knowledge to guide treatment.

Dear Dr. Roach: Recently my mom was diagnosed with diabetes. Two of her 12 siblings were diabetic. While I don’t have symptoms, would it be wise for me to get tested? I am a fairly healthy 35-year-old man. I don’t smoke, have an occasional drink, run 20-30 miles a week and have a physically active job in landscaping. The worst part is my diet, which isn’t always the best due to working long hours, coming home and eating before bed. Sometimes that includes sweets and/or carbs.


People with a family history of diabetes should have screening tests for diabetes. A screening test is done on a person with no symptoms.

If you were to develop symptoms, such as excess thirst or urination, blurry vision or unintended weight loss, you should be seen right away and evaluated solely on the basis of your symptoms. Otherwise, a screening test with your routine wellness visit is appropriate.

Most doctors use the hemoglobin A1C test, which looks at the blood sugar over the past couple of months, rather than a fasting blood glucose, which will not become abnormal until the diabetes is considerably more advanced. The most sensitive test is a two-hour glucose tolerance test, which I use when my suspicion is very high, even if the A1C is normal.

Given your family history, it is important for you to avoid processed foods, refined starches and simple sugars. Whole fruits, whole grains, vegetables, seeds and nuts are much better choices. You should also avoid eating right before bed. Try keeping a healthier snack with you to eat in the late afternoon or evening to keep you from getting so hungry that you make unwise choices at night.

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