预防水痘 2针更见效

STEVE INSKEEP, host: It's MORNING EDITION, from NPR News. I'm Steve Inskeep.

In Your Health today the topic is children. We're going to hear what's been learned from a study that counted the millions of words that parents say to their young children. But first we'll talk about childhood vaccines. In the February issues of the Journal of Infectious Disease researchers confirm what many doctors had suspected. Two doses of the chickenpox vaccine work better than one. NPR's Patti Neighmond reports.

PATTI NEIGHMOND: It was about six years after the chickenpox vaccine was introduced when unexpected outbreaks began to occur.

(Soundbite of children playing)

Outbreaks like the one in 2001 at Forest Hills Elementary School in Lake Oswego, Oregon.

Dr. PAUL CIESLAK (Department of Human Services, Oregon): In this particular school the kids were highly vaccinated. So we were struck by the fact that we had an outbreak at all to begin with.

NEIGHMOND: Which is why infectious disease specialist Paul Cieslak with Oregon's Department of Human Services decided to investigate further.

Dr. CIESLAK: Our first thought was the vaccine may not be working as well as we had thought.

NEIGHMOND: It turned out the children who ended up with chickenpox got their vaccines a number of years earlier, suggesting its effectiveness had waned and fairly quickly. Similar outbreaks in other parts of the country prompted researchers to look at whether two doses would boost effectiveness.

After study, the answer - yes. Federal officials now recommend children get two doses of the vaccine. Infectious disease specialist William Schaffner advises the government.

Dr. WILLIAM SCHAFFNER (Chair of the Department of Preventive Medicine; Vanderbilt University School of Medicine): The first dose acquaints the immune system with this vaccine and it gets revved up. But the second dose gives it, well,a kick in the pants. Now it really produces the amount of antibody that will be sustained and strong enough to protect the child completely from the infection.

NEIGHMOND: Which isn't just an annoying childhood rite of passage, says Schaffner, as many parents may think. Chickenpox can cause serious problems.

Dr. SCHAFFNER: Some children can get pneumonia. Others can be hospitalized with chickenpox encephalitis. If the disease is transmitted to a pregnant woman, she can get serious pneumonia and have a miscarriage(流产).

NEIGHMOND: The recommendation for a second dose of chickenpox vaccine is now being studied by health departments across the country, including Oregon, with one great irony. Oregon's Dr. Cieslak.

Dr. CIESLAK: We can't find any cases.

(Soundbite of laughter)

So it's one of those situations where we're supposed to be studying it, but where are the cases. So I think the bottom line is that the two-dose recommendation has really shut down chickenpox.

NEIGHMOND: And health officials hope it will also shut down a resurgence of the virus later in life - the painful and debilitating condition known as shingles(带状苞疹).

Patti Neighmond, NPR News.