Vaccinating moms to protect babies

The US Food and Drug Administration (FDA) is struggling to know how to set guidelines for research to bring about more maternal vaccination as a means of protecting the infant.

“Scientific advances and increasing recognition of unmet potential have led to a recent surge in activity and interest in maternal immunization,” the agency said in a background paper for a hearing in November 2015.

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There are currently no vaccines licensed specifically for use during pregnancy for the purpose of protecting the infant or the woman. However, there are some vaccines that are recommended for use in pregnancy.

The Centers for Disease Control and Prevention Advisory Committee on Immunization Practices (ACIP) has recommended that seasonal influenza vaccine be given to pregnant women and that Tdap be given in the third trimester. In addition, the ACIP recommends that hepatitis A and B, meningococcal, and pneumococcal vaccines be given only when the potential risks outweigh the potential benefits.

Vaccines being considered for development and for use in pregnancy to protect the infant include those for group B Streptococcus and respiratory syncytial virus.

However, the ethical and logistical issues around doing the research are difficult, speakers at the hearing told the agency.

Among the complexities is the fact that when there is a low disease incidence, clinical trials with disease endpoints may not be feasible in this country, said Marion F. Gruber, PhD, director of the FDA’s Office of Vaccines Research and Review.

For the inactivated influenza vaccines and Tdap that are licensed and already recommended for use in pregnancy, doing trials that are placebo controlled or controlled with an unrelated vaccine could be considered unethical or logistically challenging. There may be a need, Gruber said, for using endpoints in studies other than clinical disease and using study designs other than randomly controlled trials.

Over a number of years, a division at the National Institute of Allergy and Infectious Diseases has taken vaccines for maternal immunization for 6 pathogens to Phase I or Phase II clinical trials. Those are group B Streptococcus, Haemophilus influenzae type b, Streptococcus pneumoniae, pertussis and respiratory syncytial virus, and influenza.

Richard Gorman, MD, associate director of the Division of Microbiology and Infectious Diseases, National Institutes of Health, said vaccines to be studied in pregnant women ideally should have had preclinical studies done on them and reproductive toxicology testing should show no fetal toxicology. In addition, he said, the vaccine should have had Phase I and II clinical trials done in nonpregnant healthy adults, providing guidance on dosage, safety, and immunogenicity.

The FDA pointed out that another complication is that with some vaccines immunizing the pregnant woman may interfere with the baby’s mounting an optimal response to the same vaccine or another vaccine.

After the committee had discussed other factors surrounding maternal vaccination, Vicky Pebsworth, PhD, RN, director of patient safety at the National Vaccine Information Center, said she had never seen a more complex topic in her years on the committee, indicating the day was a tsunami of ethically complex and terrifying questions.

Bruce Gellin, MD, director of the National Vaccine Program Office in the US Department of Health and Human Services, said the goal is to have seamless protection of the infant. This work may even allow researchers to reevaluate and possibly “decompress” the vaccine schedule for infants, he said.

Ms Foxhall is a freelance writer in the Washington, DC, area. She has nothing to disclose in regard to affiliations with or financial interests in any organizations that might have an interest in any part of this article.