Vaccinating breast-feeding women requires care

The ACIP has formed a work group to address inconsistencies in current recommendations about vaccinating pregnant and breast-feeding women.

Issue: October 2007

The Advisory Committee on Immunization Practices recently formed a work group to discuss vaccines during pregnancy and breast-feeding.

This group was formed because “pregnant women and newborns are at risk for vaccine-preventable diseases, and yet attention toward vaccine coverage and vaccine recommendations in this group is not always optimal,” said Kathy Neuzil, MD, MPH, chair of the work group.

In March, the work group identified three main tasks:

To review current recommendations on the use of vaccines during pregnancy and breast-feeding.
To establish guiding principles for decision-making.
To facilitate resolution of inconsistencies in recommendations issued by the ACIP and to try to facilitate harmonization across professional organizations.

Although the group has not issued official recommendations, Tami Skoff, MS, from the CDC, recently presented the group’s initial findings at the annual ACIP meeting.

Current ACIP recommendations

According to the ACIP recommendations, “the risk to a developing fetus from vaccination of the mother during pregnancy is primarily theoretical. This is based on the fact that, to date, no evidence exists to support a risk from vaccinating pregnant women with inactivated virus, bacterial vaccines or toxoids.”

These recommendations also contain a statement that could be viewed as a guiding principle for vaccinating pregnant women, according to Skoff.

“The benefits of vaccinating pregnant women usually outweigh the potential risks when the likelihood of disease exposure is high, infection would pose a risk to the mother or fetus, and vaccine is unlikely to cause harm,” she said.

During its first meeting in March, the work group attempted to divide vaccines into four groups based on their interpretation of the existing ACIP recommendations: those recommended for all pregnant women, those that follow the routine adult immunization recommendations, those that are recommended only under special circumstances, and those not recommended for pregnant women.

To date, the only vaccine that is recommended for all pregnant women is the inactivated influenza vaccine. Those that follow routine adult immunization recommendations include hepatitis B, tetanus and diphtheria toxoids, and the meningococcal vaccine.

Hepatitis A, polio, anthrax, inactivated Japanese encephalitis, rabies, smallpox, yellow fever and tetanus-diphtheria-pertussis vaccines are recommended only under special circumstances, and live-attenuated influenza, measles-mumps-rubella, varicella, zoster, bacilli Calmette-Guérin and human papillomavirus vaccines are not recommended for pregnant women and it is unclear whether or not special circumstances for their use exist.

“This was our attempt to group the vaccines based on our interpretation of the recommendations. Many of the ACIP recommendations are challenging to interpret, and it is not uncommon for similar recommendations to use different languages. There also seems to be an inconsistent message about the role of limited safety and/or efficacy data for many of these vaccines,” Skoff said. “For some products, data are used to support vaccination of pregnant women, whereas for other products, the role of the data is to advise against vaccination.”

The work group also noticed that when it tried grouping the vaccines based on their recommendations, most of the vaccines were recommended for pregnant women when the benefits of vaccination outweighed the risks to the individual, according to Skoff.

“Having recommendations with this type of language is problematic, as it places a large burden on health care providers and pregnant women to make responsible decisions about vaccination during pregnancy,” she said.

Additionally, the ACIP does address the issue of breast-feeding with an overall statement supporting the vaccination of breast-feeding women, with the notable exception of the smallpox vaccine.

FDA vaccine indications

The second work group meeting focused on the FDA’s process of making indications for the use of vaccines during pregnancy and breast-feeding.

According to Skoff, as part of the FDA process, all vaccines must be classified under one of five pregnancy categories.

“These categories have led to confusion because they convey the impression that there is a gradation of risk from vaccine exposure between categories and that there is the same level of risk within a given category. That is not necessarily true,” she said. “The FDA acknowledges this, and, as a result, they are in the process of improving pregnancy labeling. They are also considering changing or creating alternatives to the current pregnancy categories.”

Currently, the vaccine companies write the vaccine labeling, and the FDA reviews and approves the label language.

The content of vaccine labeling is constrained by federal regulations. No implied claims of product use may be made if there is inadequate evidence of safety or lack of substantial effectiveness.

“In general, the language on the vaccine labeling tends to be more conservative than the ACIP recommendations,” Skoff said.

Additional recommendations

The work group’s third meeting focused on the recommendations of the AAFP, the American College of Obstetricians and Gynecologists (ACOG) and the AAP.

During this review, the work group found that the recommendations from these professional organizations are generally harmonized with the ACIP recommendations. However, it is the interpretation of the recommendations may vary.

“The biggest difference in recommendations seen was for Tdap, which is recommended for pregnant women by AAP and is under consideration for similar recommendation by ACOG,” Skoff said. – by Michelle Stephenson

For more information:

Neuzil K, Skoff T. Update: ACIP working group on vaccines during pregnancy/breastfeeding. Presented at: the annual meeting of the Advisory Committee on Immunization Practices; Atlanta; June 27-28, 2007.