Dr. Roach: An injection in the arm can protect the whole body

Keith Roach
To Your Health

Dear Dr. Roach: I have had over 50 vaccinations in my life (I’m 78), most of them while I was in the military. I have often wondered how the vaccine spreads throughout the body, as the shots are almost always given in the upper arm. I would welcome your explanation of what exactly takes place. Pardon my ignorance.

— C.C.

Dear C.C.: Recognizing what you don’t know is a sign of wisdom, not weakness.

Dr. Keith Roach

Vaccination is a way of establishing immunity to an infection without getting the actual disease. The term “vaccine” itself is from the Latin word for “cow,” recalling how exposure to cowpox caused only a mild skin reaction but provided lifelong protection against the deadly disease smallpox.

A vaccine usually consists of a weakened form of the bacteria or virus causing the disease to be protected against, or a small, noninfectious, purified part of the germ. After an injection, the inflammatory and immune cells of the body not only destroy the components of the vaccine in your arm, they can “remember” what was injected. This allows the body to be prepared to destroy the actual infection should you get exposed. Even though the vaccine is destroyed and removed from the body within a few days, the memory cells will usually last your whole life, and many vaccines thus provide a lifetime of protection. Other vaccines require periodic booster shots to maintain high enough immunity to protect you.

The first two COVID-19 vaccines use a new technique: mRNA “tells” the muscle cells in the arm to make a specific protein (the “spike protein”) that the coronavirus uses to enter cells. Once again, the mRNA and the spike protein are destroyed by the natural systems of the body, but not before the body learns how to recognize this critical part of the coronavirus. These vaccines have proven to be very effective at preventing infection, especially serious infection.

Vaccines can be given in other parts of the body. Some are given into the gluteal muscle, especially in children. Some are given orally. But all approved vaccines, even those for emergency use, have been proven to be effective.

Dear Dr. Roach: I have osteoporosis caused by heartburn medication. So now what type of osteoporosis medicine can I take?

— B.K.

Dear B.K.: Proton pump inhibitors such as omeprazole (Prilosec) can interfere with the body’s ability to absorb calcium. There is a small increase in osteoporosis among long-term users of PPIs, although the evidence for an increase in fractures is less convincing. Still, I recommend increasing dietary calcium in women and men on long-term proton pump inhibitors — and think twice before using proton pump inhibitors long term to begin with, unless they are absolutely needed.

If a person continues to have osteoporosis despite adequate calcium intake, and if the PPI has been stopped or can’t be, then it is reasonable to consider medication treatment for the osteoporosis. It may be that you were going to develop osteoporosis even without being on a PPI.

First-line treatment for osteoporosis is usually a bisphosphonate, such as alendronate (Fosamax) or risendronate (Actonel), since there is strong evidence that they are effective at preventing fractures. People taking these medications should be re-evaluated after three to five years of treatment. Treatment may often be stopped or paused then, as there is a risk of atypical fractures of the hip after that time.

Readers may email questions to ToYourGoodHealth@med.cornell.edu.