Med reduces effectiveness of vaccines

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

P.H.

Answer: Rituximab 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 anything that I would call a red flag symptom, would it be wise for me to get tested? Can I go to my doctor and have them run a test without having any major symptoms?

M.D.F.

Answer: People with a family history of diabetes (parents or siblings) should absolutely receive screening tests for diabetes. A screening test is done on a person with no symptoms at all.

If you were to develop symptoms, such as excess thirst or urination, blurry vision or unintended weight loss, you should be seen right away. 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.

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