Strange as it seems to those of us who remember that horrible itchy spottiness, chickenpox is no longer a normal part of childhood. Instead, kids these days get the varicella (chickenpox) vaccine. Researchers at the Centers for Disease Control and Prevention looked at how the introduction of the vaccine decreased the number of people who die from chickenpox.

What the researchers wanted to know: How did the rate of deaths due to chickenpox change after children started getting vaccinated in 1995?

What they did: The researchers used government statistics on causes of death. They were looking not only at deaths that had chickenpox as the underlying cause but also those for which chickenpox was a contributing cause. They found 1,465 chickenpox-related deaths between 1990 and 2001.

What they found: Between 1990 and 1998, chickenpox deaths went up and down, but they fell steadily from 1999 to 2001. In the early '90's, chickenpox contributed to an average of 145 deaths a year; between 1999 and 2001, deaths averaged 66 a year. The rates went down only in people under age 50; death rates fell the most in children ages 1 to 4.

What the study means to you: The lower death rates are probably partly because people who might have died got vaccines instead, so they didn't get chickenpox, and partly because of herd immunity—with so many vaccinated kids, the virus that causes chickenpox has a tougher time finding vulnerable hosts, so it doesn't move around as easily as it did when I was in second grade. But if the vaccine wears off with time, that could leave vaccinated kids open to infection later in life. As with any infectious disease, throwing a vaccine into the mix completely changes the epidemiology of the chickenpox virus, and it will take time to see exactly how.

Caveats: The researchers say their finding that chickenpox deaths didn't decline in people over 50 might be because deaths from shingles (herpes zoster) are often incorrectly classified as chickenpox (varicella). Shingles is caused when the virus that causes chickenpox wakes up after years of hiding in the body.

Find out more: Read about chickenpox at the National Library of Medicine's website.

There's a long article on chickenpox at Kidshealth.org.

An Australian website on chickenpox for kids

Read the article: Nguyen, H.Q., et al. "Decline in Mortality Due to Varicella After Implementation of Varicella Vaccination in the United States." New England Journal of Medicine. Feb. 3, 2005, Vol. 352, No. 5, pp. 450–-458.

Abstract online: http://content.nejm.org