WASHINGTON — Americans finally can prevent that itchy and sometimes dangerous rite of childhood: The government approved the nation’s first chickenpox vaccine Friday.
Merck & Co.’s long-awaited Varivax vaccine, called “a milestone” by the Food and Drug Administration, will be available in doctors’ offices within eight weeks.
Varivax is 70 percent to 90 percent effective at preventing any chickenpox, and even those who are stricken by the virus after taking the vaccine have a much milder disease, the FDA said.
“I’m ecstatic,” said Rebecca Cole, a North Carolina mother who has pushed the FDA to approve the vaccine for almost seven years, after her son died of chickenpox. “I think we’re going to see an end to chickenpox as we know it.”
“It was worth the wait,” said Dr. Thomas Vernon, vaccine chief at Merck, where scientists have been researching a chickenpox vaccine for 29 years.
Some 4 million Americans, mostly children, get chickenpox every year. Typically it’s a nuisance disease, keeping bump-covered students out of school and their parents out of work for about a week.
But it can be deadly, killing up to 90 people a year and hospitalizing 9,300. It is most dangerous to infants, adults and people with immune problems, either from diseases or from drugs that depress immunity.
Chickenpox starts as an itchy rash, covering the typical patient with 250 to 500 blisters within days. It is spread by coughing, sneezing and the fluid from broken blisters. It is highly contagious from two days before the rash appears until all the lesions are dried into scabs.
Varivax is made from the live virus that causes chickenpox, called varicella, but weakened enough so that it triggers immunity without causing disease.
After the announcement of Varivax, the American Academy of Pediatrics urged everyone eligible who has never had chickenpox to get vaccinated. Children ages 1 to 12 would get a single injection; teen-agers and adults need two shots, four to eight weeks apart.
The vaccine cannot be given to children younger than 1, even though at least 5 percent of infants develop chickenpox. But doctors still expect infants to suffer less as rising vaccine rates lower the amount of chickenpox in the environment.
It also cannot be given to children taking aspirin or steroids unless those medications are temporarily stopped.
The shots can be given at the same time as the measles, mumps and rubella vaccine, and will cost physicians $39. Side effects include redness, hardness and swelling at the injection site and some mild fatigue and nausea.
Merck has tested Varivax in 11,000 Americans since 1981. The tests showed Varivax was highly effective at preventing chickenpox. Also, the few people who still got chickenpox had very mild cases, getting fewer than 50 lesions.
Nobody knows just how long Varivax will protect. Merck will study tens of thousands of vaccinated patients to determine whether people will need booster shots later.
Another unanswered question: How Varivax will affect shingles, a very painful disease primarily among the elderly that is caused by varicella virus that hibernates in the body for decades. There is no sign Varivax will increase shingles, and Merck cites one study that indicates it might actually cut cases by one-fifth, but the company will study that as well.