Drug & Device Development

Faster hepatitis B vaccine schedule has benefits in pregnancy

Last Updated: 2011-05-06 12:00:22 -0400 (Reuters Health)

By Megan Brooks

NEW YORK (Reuters Health) - When women at high risk for hepatitis B become pregnant, an accelerated vaccination schedule takes advantage of their more-frequent health care visits and helps get them immunized against the virus, researchers say.

Compared to the usual 6-month protocol, the 4-month schedule is safe and effective and may let more women complete the three doses during the window of pregnancy, suggest results of a prospective clinical trial.

Pregnancy is an ideal time for preventive care because women regularly see their physicians, but this time is "limited" and giving the 3-dose hepatitis B vaccine series as recommended at 0, 1 and 6 months is sometimes difficult to complete before delivery, the study team notes in the May issue of Obstetrics and Gynecology.

First author Dr. Jeanne S. Sheffield, from The University of Texas Southwestern Medical Center Department of Obstetrics and Gynecology in Dallas told Reuters Health: "We have a large population of pregnant women deemed high-risk for hepatitis B. Hepatitis vaccine is recommended in these women, even while pregnant. However, some of our women are lost to follow-up after pregnancy."

"We were concerned," she added, "that using the 6-month regimen we would lose a number of women before receiving their final dose. The 4-month regimen would be better suited to the limited time course afforded by pregnancy," but it had not been studied in that setting until now.

The researchers explain in their report that US federal guidelines currently recommend a minimal interval of 4 weeks between the first and second dose and 16 weeks between the first and third dose. "Therefore, a vaccination schedule of 0, 1, and 4 months would be the shortest recommended schedule that still offers protective long-term immunity."

They tested this accelerated schedule in 200 pregnant women at high risk for hepatitis B virus, i.e., women who were surface antigen negative. Eligible women were between 16 and 45 years old and less than 25 weeks pregnant (to receive all three doses before delivery). Exclusion criteria included a history of hepatitis B vaccination or infection, hepatitis B surface antigen-positive test result, allergy to yeast in hepatitis B vaccine and immunomodulatory drug use or immunocompromise.

Overall, 84% of the women (168 of 200) received all three doses of vaccine during pregnancy on the accelerated 4-month schedule.

"The vaccine was well tolerated in pregnancy (no serious adverse events) and the accelerated vaccine schedule was equally as efficacious in pregnancy as reported prior in the non-pregnant population," Dr. Sheffield told Reuters Health.

Seroconversion rates, defined as hepatitis B surface antigen 10 milli-international units per mL or greater, were 56% after one dose, 77% after two doses and 90% after three doses. This compares favorably to seroconversion rates in healthy adults using the standard 0, 1, and 6-month regimen (30% to 55% after the first dose, 75% after the second dose, and greater than 90% after the third dose).

The 6-month and the 4-month schedule "both appear to have similar efficacy though have not been compared head-to-head in pregnant women. The 4 month regimen allows for more of our women to complete the vaccine series," Dr. Sheffield commented.

She said "time course is the main disadvantage of the standard schedule," adding: "I can think of no major disadvantage to the accelerated schedule in pregnancy at this time."

Body mass index was the only factor associated inversely with seroconversion, but there was no single body mass index above which seroconversion did not occur, the investigators note.

They conclude that the accelerated vaccine schedule in pregnancy "provides another strategy to decrease hepatitis B virus disease and transmission that can be completed before delivery."

SOURCE: http://bit.ly/kAcNGJ

Obstet Gynecol 2011;117:1130-1135.