They found that more babies exposed to hepatitis B through their moms have gotten vaccinated right away, and fewer have ended up with chronic infections, since the program started in 1990.
That's important because the virus can be passed between mother and child during birth, and over the long run chronic infection increases the risk of liver failure and cancer.
"The findings were very encouraging -- they showed that most infants completed the (vaccination) series," said Emily Smith, the lead researcher on the study.
"For the infants that were followed... they had great results and outcomes," she told Reuters Health.
Still, Smith emphasized that there's work to be done in making sure all new moms with hepatitis B are reported to the CDC's program so that babies can receive the proper care to prevent infection.
40,000 new infections per year
About one million people living in the United States have chronic hepatitis B infection, and an additional 40,000 are infected every year though bodily fluids such as blood and semen -- as well as during birth.
The CDC's vaccine program calls for screening all pregnant women for hepatitis B and giving exposed babies antibodies and a vaccine against the virus within 12 hours of birth, followed by an additional two or three vaccine doses over the next year or so. Individual cities and states submit reports to the CDC on the number of hepatitis B cases identified in women and how their infants were managed, and those numbers are used to make nationwide estimates.
Based on those reports, the researchers calculated that from 1994 to 2008, the number of women who screened positive for hepatitis B each year increased from about 19,000 to close to 26,000. And health care workers seemed to get better at making sure their babies were protect against the virus.
Over the study period, the number of exposed babies who got both hepatitis B antibodies and a vaccine within a day of birth increased from 92 percent to almost 97 percent.
Along with that, tracked infants who ended up with chronic hepatitis B infection fell from two percent to less than one percent by 2008, the researchers reported in Pediatrics.
Longer follow-up needed
Still, they were only able to follow about half of babies out to one year. And the number of infants who'd had all of their hepatitis B vaccines by that point actually decreased during the study period -- from 86 percent to 78 percent -- with at least some of that due to more families refusing vaccines.
"The program is certainly working -- they're vaccinating more infants successfully," said Dr. Maya Gambarin-Gelwan, who has studied hepatitis B at Weill Cornell Medical College in New York but wasn't involved in the new research.
"But half of the infants who are born to those mothers are slipping through the system essentially," she told Reuters Health. "It's also bothersome that there's this growing percentage of infants who are not completing vaccination or that we don't have a follow-up on."
Smith agreed that not being able to follow infants over time is a problem.
"Women need to receive hepatitis B screening and positive results need to be reported to (the program), to make sure that the infants receive vaccination and care and testing," she said.
Gambarin-Gelwan added that it's important to get the message out that hepatitis B programs really do work when babies get all of their recommended vaccines, especially to communities with high virus rates, such as among Asian-Americans.
Dr. Tram Tran from Cedars-Sinai Medical Center in Los Angeles told Reuters Health that while doctors are really good at screening women early in pregnancy when they're already in the health care system, there's still a big gap for other women, such immigrants and illicit drug users.
And even if those women do get screened, she said, they may not have the resources to bring their babies back for the multiple hepatitis B shots necessary for protection.
"It's a completely preventable disease, that's the thing that's frustrating," said Tran, a hepatitis researcher who wasn't part of the study team.
"We have a vaccine that works really well. It's just getting to these high-risk pockets and these high-risk groups where there's still a lot of opportunity."