New vaccine differs from prior version

Dear Dr. Roach: I am a 60-year-old woman who has been taking a 200-mg tablet of acyclovir (Zovirax) every day for HSV-2 suppression. I may have an outbreak every few years, and they are pretty mild. When I do have an outbreak, I increase my dosage to 1,000 mg per day. What is the procedure when I want to get the shingles vaccine (Shingrix)? Would I need to stop taking the acyclovir for two weeks before getting the vaccine and then be able to continue after? Does taking acyclovir help suppress shingles? — B.S.

Acyclovir, as well as the related valacyclovir (Valtrex) and famciclovir (Famvir), is an antiviral drug that is used for treatment and sometimes suppression of herpes viruses.

Shingrix is a new, two-dose vaccine for shingles. It is a subunit vaccine, meaning it is made from a viral protein, not from the live virus. You do not need to stop taking the acyclovir before getting the two doses of the vaccine. With the live vaccine (Zostavax), you did need to stop acyclovir, in just the way you suggested.

That’s another advantage of the new vaccine, but the most important advantage is that the new vaccine is much more effective. Disadvantages include its high cost, the need for two doses and a higher incidence of mostly local side effects, such as sore arm, but also fever and just feeling poorly. There is, unfortunately, a shortage in most of the U.S.

Regular doses of acyclovir to chronically suppress herpes outbreaks does reduce the risk of shingles in a high-risk group of people with HIV infection. However, the Shingrix vaccine provides more potent and long-lasting protection.

Many physicians recommend that you try going off the acyclovir to see if you get recurrences of the HSV-2 (one of eight strains most commonly the cause of genital herpes) so often. That part is up to you.