Chickenpox Vaccine Goes on Market

Merck & Co. on Monday began shipping millions of doses of the nation’s first chickenpox vaccine, Varivax.

About 4 million Americans, mostly children, get chickenpox every year. Typically it’s a nuisance disease, keeping bump-covered students out of school for about a week.

But it can be deadly--it kills up to 100 people annually and hospitalizes 9,300. Chickenpox is most dangerous to infants, adults and people with weakened immunity.

The Food and Drug Administration approved Varivax last month, calling it up to 90% effective at preventing chickenpox and saying the few who still got the virus had much milder cases.

The American Academy of Pediatrics urged every eligible child to be vaccinated.