DEAR DR. ROACH: My husband and I both took the first dose of the Shingrix vaccine as prescribed by our physician in July 2018. We were told we would need to have the second dose administered within the next four to six months. I receive constant notices via email from GlaxoSmithKline reminding me to get our second vaccine and telling me how many weeks I have left — “It is important to get your second, and last, shot of SHINGRIX in three weeks …”

The problem is that the second dosage seems to be totally unavailable, both in my home state of New York and in my winter home in Florida. What are the repercussions if we are unable to get the second dose within the six-month window? — R.S.

ANSWER: The guidance from the Centers for Disease Control and Prevention to doctors and pharmacies states: “If more than six months have elapsed since the first dose, administer the second dose as soon as possible. Do not restart the vaccine series, and do not substitute Zostavax for the second dose of Shingrix. If you are out of Shingrix and a patient needs a second dose, the Vaccine Finder may be helpful for patients to locate other providers that have Shingrix.”

Pharmacies and providers should give first priority for the limited amount of the vaccine to people in your situation: those due or overdue for their second dose.