Sharp drop in U.S. chickenpox deaths with vaccine

NEW YORK Mon Jul 25, 2011 4:03am EDT

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NEW YORK (Reuters Health) - Deaths from chickenpox, although rare, have dipped steeply after the U.S. began vaccinating against the virus in 1995, a new government report concludes.

Since the early 1990s, the bug has gone from killing 105 a year to causing fewer than 20 annual deaths between 2003 and 2007.

Writing in the journal Pediatrics, researchers from the Centers for Disease Control and Prevention (CDC) call the results "impressive" and say they show the benefit from the vaccine program is larger than expected.

Chickenpox is caused by the varicella zoster virus and produces fever and an itchy rash. In rare cases, it can be complicated by bacterial infections, swelling of the brain or pneumonia.

Before vaccination became mandated, a few million Americans caught the infection every year. Although most cases are mild, thousands of people landed in the hospital due to the disease.

Now, the number of people who get infected has been cut dramatically. The CDC's new report, which updates an earlier analysis from 1995 to 2001, shows deaths have dropped by as much as 88 percent over the first 12 years since the varicella vaccine was introduced.

That's a decline from 0.41 to 0.05 annual deaths per one million Americans between the early 1990s to the mid-2000s.

The varicella vaccine is mandated in all states, and in 2006 the dose was upped from one to two shots, which researchers say give better protection.

About a fifth of infants get some swelling and soreness around the injection site, and 10 percent also experience passing fever. Fewer than one in 1,000 of those who get the shot also develop a seizure from the fever, although experts say it's usually harmless.

Varivax, a varicella vaccine developed by Merck, costs about $84 per dose, but the new report says the vaccination program has exceeded expectations in terms of cost-effectiveness.

"Our analysis documents the impressive impact on varicella mortality of the US vaccination program, largely during a period when only 1 dose was administered," the researchers conclude. "With the current 2-dose program, there is potential that these most severe outcomes of a vaccine-preventable disease could be eliminated."

SOURCE: Pediatrics, online July 25, 2011.

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Comments (1)
bensmyson wrote:
What about increases in shingles (Herpes zoster) in vaccinated children? Multiple studies and surveillance data, at least when viewed superficially, demonstrate no consistent trends in incidence in the U.S. since the chickenpox vaccination program began in 1995. However, upon closer inspection, the two studies that showed no increase in shingles incidence were conducted among populations where varicella vaccination was not as yet widespread in the community. A recent study by Patel et al. concluded that since the introduction of the chickenpox vaccine, hospitalization costs for complications of shingles have increased by more than $700 million annually for those over 60 years. Another study by Yih et al. reported that as varicella vaccine coverage in children increased, the incidence of varicella decreased and the occurrence of shingles among adults increased 90%. The results of a further study by Yawn et al. showed a 28% increase in shingles incidence from 1996 to 2001.

Jul 25, 2011 8:10am EDT  --  Report as abuse
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