Kim Lamb Gregory

At first, Phil Patterson, 69, thought it was an insect bite he got from working in the yard. But by the next day, he and his wife, Sandra, a retired nurse, knew it was more serious. The one raised, itchy bump had spread into a patch of bumps.

"It was all over the right side of his trunk, front and back," Sandra Patterson, 67, said.

The Newbury Park, Calif., couple soon learned that he was suffering from shingles, a viral infection that causes a painful rash that can flare up in anybody who has ever had chickenpox -- more than 95 percent of the population, according to medical experts.

Although there is a shingles vaccine, approved in 2006 by the U.S. Food and Drug Administration, only about 10 percent of people who should get it are being vaccinated, according to a federal Centers for Disease Control and Prevention survey released in late 2010.

The CDC estimates that about 1 million Americans each year develop shingles. The severity varies, but the pain can be so great that it can be life-altering, according to Dr. Bill Schaffner, president of the National Foundation for Infectious Diseases.