Q: I recently saw a patient who developed herpes zoster with significant corneal findings. He contracted the disease even though he had been vaccinated (Zostavax, Merck) seven months prior. How effective is the vaccination, and is there a period of time afterward that is considered protective?

A: Zostavax essentially is a booster shot designed to increase the number of circulating immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies to the varicella zoster virus. “It generally takes the body anywhere from two weeks up to three to four months to develop enough IgG antibodies to be detectable in the blood,” explains Benjamin Smith, O.D., staff optometrist at Eye Associates of New Mexico, in Albuquerque. “Thus, there is a gap between when the vaccine is administered and when patients develop immunity.”

Like most vaccines, Zostavax does not guarantee 100% effectiveness even after that gap has elapsed, especially with a “wild type” virus. “There will always be cases of disease occurrence despite inoculation, and many cases can slip past the vaccine,” says William Potter, O.D., chief of optometry and contact lens services at Millennium Eye Care, in Freehold, N.J. “However, Zostavax’s excellent safety profile makes it a viable treatment in terms of disease prevention and limitation of post-herpetic neuralgia.”

In a study of more than 38,000 people, the vaccine reduced the risk of developing shingles by 51% and post-herpetic neuralgia by 67%.¹ After inoculation, herpes zoster occurred in seven patients who had received the vaccine vs. 24 who had taken the placebo. Long-term follow-up revealed that rates of hospitalization or death didn’t differ between the vaccine and placebo groups.

Zostavax was licensed and recommended in 2006 for prevention of herpes zoster in patients ages 60 and older. In March 2011, the FDA approved its use for adults ages 50 to 59, but the Advisory Committee on Immunization Practices declined to change its current stance that the herpes zoster vaccine be routinely recommended for adults ages 60 and older.²

The Center for Disease Control and Prevention reported a 64% reduction in shingles cases in the 60- to 69-year-old age group, and just a 38% reduction in the over-70 age group.³

The vaccine does not confer lifelong immunity—most studies suggest it protects patients for approximately five to seven years. It also is now acceptable to give the vaccine to patients even after they have experienced the herpes zoster virus, but it’s probably prudent to avoid, if there were significant corneal or intraocular findings. Most physicians wait about one year following the event. Keratoplasty patients should increase their steroid use for a week or two following any vaccination such as Zostavax. 

“Most humans harbor the herpes zoster virus throughout life. Outbreaks are limited because the immune system keeps it in check,” Dr. Potter says. “Aside from proper vaccination, it is critical to maintain diet and medical treatments that help prevent immunosuppression. Substance abuse, fatigue, stress and illness can all play a role in weakening the human immune response to infection.”

1. Simberkoff MS, Arbeit RD, Johnson GR, et al. Safety of herpes zoster vaccine in the shingles prevention study: a randomized trial. Ann Intern Med. 2010 May 4;152(9):545-54.
2. Centers for Disease Control and Prevention. Update on herpes zoster vaccine: licensure for persons aged 50 through 59 years. MMWR. 2011 Nov 11;60(44):1528.
3. Centers for Disease Control and Prevention. Herpes zoster vaccine for health care professionals. Available at: www.cdc.gov/vaccines/vpd-vac/shingles/hcp-vaccination.htm (accessed November 20, 2011).