Lifelong Immunity? With Vaccines, It Depends (NPR)

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Lifelong Immunity? With Vaccines, It Depends

by Shute October 11, 2010

At 2:30 on a Tuesday afternoon, moms and babies are gathering at

Shogren's townhouse in andria, Va. As the babies try to crawl across the

basement floor, the moms talk about breastfeeding and lack of sleep. One issue

keeps coming up: vaccines.

" I am from Peru, " says Vohden, mother of 4-month-old Santiago. " Polio —

it's still there. I grew up seeing kids in wheelchairs from polio. So I am

definitely pro-immunization. "

The other moms are pro-immunization, too. But that doesn't mean they don't have

big questions about the vaccines their babies get. They worry about the number

of vaccines that the federal Centers for Disease Control and Prevention

recommends for children: more than 20 by age 2, including the new recommendation

for seasonal flu shots for all children 6 months and older.

Vaccines have tamed killers like smallpox, polio and measles; they may well be

medicine's greatest triumph. But newer vaccines, like the ones for whooping

cough and chicken pox, don't always give such great protection.

The moms at the get-together wonder if it would be easier on babies' brand-new

immune systems to spread those shots out. And they wonder if vaccines for

diseases like chicken pox, which usually causes mild illness, are really

necessary.

" I think natural immunity for non-serious illnesses like chicken pox may be

better than getting the vaccines, " says Combs, mother of 6 1/2-month-old

Charlotte.

Different Levels Of Immunity

It turns out that there are no simple answers to the question of whether natural

immunity caused by exposure to a germ is better than the industrial version. " It

varies from vaccine to vaccine, " says Katz, an inventor of the measles

vaccine and a chairman emeritus of pediatrics at Duke Medical School.

But he still doesn't know why some vaccines work well — and some, not so much.

" There are at least two systems in the immune function, " Katz says. " One is

called antibody, and the other is called cell-mediated immunity. And with most

infections, we'd like to have both of those active. "

The human body uses those immune systems to fight off viruses and bacteria. Once

those systems are activated, they can remember the bugs and stand ready to fend

off new infections for years — or even for a lifetime.

" We think that's what we've achieved with measles, " Katz says. " We think that's

what we've achieved with polio. "

But other vaccines, whether because of the nature of the microbe or the vaccine

itself, don't confer lifetime immunity. The vaccine for pertussis, or whooping

cough, is one of those.

" We're seeing right now in California, where they're having a large outbreak,

that a number of cases are individuals who've received the vaccine, " Katz says.

Giving Some Vaccines A Boost

When vaccines don't work so well, the solution is to give multiple doses, or

boosters. Children now get a pertussis booster around age 12, and adults are

being told to get a pertussis booster every 10 years. That's especially

important if they are around babies who are too young to be fully protected by

vaccines.

Chicken pox is another example of a vaccine that doesn't work as well as doctors

wish. After one shot of the vaccine, which was licensed in the United States in

1995, about 25 percent of children were still spreading the varicella virus

around, or getting sick themselves. Anne Gershon, a chicken pox expert who is

director of the division of pediatric infectious disease at Columbia University

Medical Center, says, " We really need boosters of vaccines much more than we

thought we ever would. "

So in 2006, the CDC recommended that a second chicken pox shot, to be given when

children are 4 to 6 years old, be added to the list of childhood vaccines.

Gershon says it looks like that second shot will keep children from getting

sick. But the varicella virus that causes chicken pox is a wily bug. Even with

the vaccine, it may hide out in nerves for years, and return to cause the

painful rash of shingles.

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" I don't think we'll ever completely get rid of the virus, " Gershon says. " But

we can make a lot of difference with how much really severe disease that we

see. "

Gershon understands why parents like Combs wonder if the chickenpox vaccine is

worth the trouble. Before the vaccine, deaths from chickenpox were rare: about

100 people a year. Rare but serious complications include pneumonia and

infections with streptococcus A flesh-eating bacteria, which can enter the skin

through chickenpox sores.

Even though the vast majority of chickenpox cases were mild, Gershon says, " I

think it's important to keep in mind with these infections that we look not only

at dying, but suffering from the virus. "

Seeking More Control

But even pro-vaccine parents like the mothers at the andria meet-up wish

that pediatricians and the CDC would acknowledge that all vaccines are not the

same.

Kiersten Petrucci went to three pediatricians before she found one who would let

her delay some of the shots for her son Collin. She wishes that more physicians

were willing to educate parents about the importance of vaccines, but also work

with parents and their concerns.

" Not by ramrodding it and saying you absolutely must follow the CDC guidelines.

That's my hope, " she says

Her pediatrician agreed to let the family skip the rotavirus vaccine for Collin,

figuring that she could help them treat the stomach flu and diarrhea it causes.

And they agreed to delay the hepatitis B vaccine, and space out other vaccines

so that Collin wouldn't be getting as many as four in one day. He's now a happy,

healthy 5-month-old. And his mom is happy that she had some control over his

vaccines.

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