Shingles shot's value is uncertain.

The cost-effectiveness of a new vaccine against shingles remains uncertain, according to a new study. So, health policy makers don't have enough information to recommend for or against routine use of the shot, say the researchers.

Shingles, also called herpes zoster, develops when a person previously infected with chickenpox experiences a reactivation of the dormant virus. Nationwide, shingles annually affects 300,000 to 600,000 people. People usually recover within a month, but some later experience flare-ups of severe pain.

Zostavax, a vaccine made by Merck & Co. of Whitehouse Station, N.J., and given to people who haven't had shingles, lessens the incidence and severity of symptoms in people age 60 and older (SN: 6/4/05, p. 358). The government approved the vaccine's sale in May, and its list price is about $150.

Recently, physician John Hornberger and analyst Katherine Robertus, both of the research firm Acumen in Burlingame, Calif., used Merck's data on the vaccine's efficacy to calculate cost-effectiveness, which could influence how willing insurers are to pay for the shot.

In the Sept. 5 Annals of Internal Medicine, the researchers conclude that the vaccine is more cost-effective in people in their early 60s than in people 80 and older. That's because the younger group's immune response to vaccination is stronger, and longer life expectancy multiplies any benefit, the researchers say.

However, the overall cost-effectiveness is difficult to gauge, Hornberger says. First, researchers have few data to use in attempting to pin a dollar value on people's suffering from shingles. Second, Merck's study ran for just 3 years, so it's unclear how long the vaccine's protection lasts.

Says Hornberger, "If it only lasts 5 years, and then you have to revaccinate, then it certainly isn't cost-effective in any population." --B.H.