VACCINE, INFLUENZA

Fetal Risk Summary

Influenza vaccine is an inactivated virus vaccine (1). Animal reproduction studies have not been conducted with the vaccine.

Influenza during pregnancy may potentially result in an increased rate of spontaneous abortions (1). The vaccine is considered safe during all stages of pregnancy (2,3,4 and 5). Neonatal passive immunization of short duration has been documented in some studies (4). The American College of Obstetricians and Gynecologists recommends that the vaccine be given only to pregnant women with serious underlying diseases and that public health officials should be consulted for current recommendations (1).

In 1999, the Advisory Committee on Immunization Practices (ACIP) recommended that the vaccine should be administered to women who would be in the 2nd and 3rd trimester (i.e., ³14 weeks' gestation) during the influenza season (5). In addition, pregnant women who have medical conditions that increase their risk for complications from influenza should receive the vaccine regardless of the stage of pregnancy (5). Moreover, many experts consider influenza vaccine safe at any time in pregnancy, but vaccination during the 2nd trimester can avoid a coincidental association with spontaneous abortion that is common in the 1st trimester (5).

Breast Feeding Summary

Maternal vaccination is not contraindicated during breast feeding and presents no risk to the nursing infant (5).

References

1. American College of Obstetricians and Gynecologists. Immunization during pregnancy. Technical Bulletin. No. 160, October 1991.
2. Philit F, Cordier J-F. Therapeutic approaches of clinicians to influenza pandemic. Eur J Epidemiol 1994;10:491–2.
3. Bandy U. Influenza: prevention and control. R I Med 1994;77:393–4.
4. Linder N, Ohel G. In utero vaccination. Clin Perinatol 1994;21:663–74.
5. CDC. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999;48(No. RR-4):1–28.