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Immunization During Pregnancy

WHEC Practice Bulletin and Clinical Management Guidelines for healthcare providers. Educational grant provided by Women's Health and Education Center (WHEC).

The purpose of this document is to understand immunization during pregnancy. Immunization saves lives and prevents disease. There are many national resources available to help you fine-tune your vaccination practices. If you have not yet incorporated vaccination into your practices, now would be a great time to start.

Immunizations are considered one of the major medical achievements of the 20th century. However, inadequate vaccination remains an important public health problem. This document reflects emerging clinical and scientific advances and current information on the safety of vaccines given during pregnancy. The benefits of immunization to the pregnant woman and her neonate usually outweigh the theoretic risk of adverse effects. The theoretic risks of the vaccination of pregnant women with killed virus vaccines have not been identified.

Pre-conceptional immunization of women to prevent disease in the offspring, when practical, is preferred to vaccination of pregnant women with certain vaccines. Vaccination of women during the postpartum period, especially for rubella and varicella, should be encouraged. Women susceptible to rubella should be vaccinated with measles-mumps-rubella (MMR) vaccine on postpartum discharge from the hospital.

Immunization During Pregnancy:
(Abbreviations - Intradermally, ID; Intramuscularly, IM; Orally, PO; Subcutaneously, SC)

I. Live Virus Vaccines:

Contraindicated in pregnancy. Vaccination of susceptible women should be the part of postpartum care. Breastfeeding is not a contraindication. Postponement of travel is preferable to vaccination, if possible. The various vaccines in this category are:

• Measles: the risk of disease to the pregnant woman has significant increase in abortion rate, and may cause malformations in fetus. The disease has significant morbidity, low morbidity not altered by pregnancy. Dose schedule - single dose SC, preferably as measles-mumps-rubella vaccine (MMR).
• Mumps: there is increased risk of abortion and the disease has low morbidity and mortality, not altered by pregnancy. Dose schedule - single dose SC, preferably as measles-mumps-rubella vaccine (MMR).
• Poliomyelitis: anoxic fetal damage is reported and 50% mortality in neonatal disease. There is no increased incidence in pregnancy, but may be more severe if it does occur. Dose schedule - Primary: two-doses of enhanced-potency inactivated virus SC at 4-8 week intervals and a third dose 6-12 months after the second dose. Immediate protection: one dose oral polio vaccine (in out-break setting). Live attenuated virus (oral polio vaccine) and enhanced potency inactivated virus vaccines are available. Vaccine is indicated for susceptible pregnant women traveling in endemic areas or in other high-risk situations. Killed virus polio vaccine (IPV) can be given to the pregnant woman. Oral PV is no longer given due to the risk of vaccine-associated paralytic poliomyelitis.
• Rubella: high rate of abortion and congenital rubella syndrome is seen in the patients infected with rubella during pregnancy. The risk of disease to pregnant women is of low morbidity and mortality not altered by pregnancy. Dose schedule- single dose SC, preferably as measles-mumps- rubella vaccine (MMR).
• Yellow fever: it has significant morbidity and mortality during pregnancy but is not altered by pregnancy. Risk from disease to fetus and neonate is unknown. Dose schedule - single dose SC.
• Varicella (VZV): there is increased incidence of severe pneumonia and it can cause congenital varicella in 2% of fetuses infected during the second trimester. The vaccination is contraindicated during pregnancy but no adverse outcomes reported if given in pregnancy. Teratogenicity of vaccine is theoretical, outcomes reported weeks 4-8 is not confirmed to date. Vaccination of susceptible women should be considered postpartum. Dose schedule - two doses needed with second dose given 4-8 weeks after first dose.

II. Other Vaccines:

Indications for prophylaxis is not altered by pregnancy and each case should be considered individually. Pre-exposure and post-exposure for women at risk of infection should be taken into account. International travelers may be considered for immunization during pregnancy. The vaccines in this category are:

• Influenza: this is inactivated virus vaccine. Influenza has increase in morbidity and mortality during epidemic of new antigenic strain and it has possibility of increased incidence of abortion rate. There are no malformations confirmed. All women who are pregnant in the second and third trimester during flu season (October-March) and women at high risk for pulmonary complications regardless of trimester should be considered for vaccination. Do not give influenza vaccine to a person who has had a serious reaction to eggs, to a previous dose of influenza vaccine, or to one of its components. You cannot give live attenuated influenza vaccine (LAIV) to pregnant patients. Dose schedule - one dose IM every year.
• Rabies: this is killed virus vaccine. Rabies is nearly 100% fatal; not altered by pregnancy. Indications for prophylaxis is not altered by pregnancy and each case should be considered individually. Public health authorities should be consulted for indications, dosage and route of administration.
• Hepatitis B: it is purified surface antigen produced by recombinant technology type of vaccine. Possibility of increased severity of the disease during third trimester is seen. There is possibility of increased incidence in abortion rate, preterm birth, neonatal hepatitis and high risk of newborn carrier state. Dose schedule - three-dose series IM at 0, 1, and 6 months. Hepatitis B vaccine is also used with hepatitis B immune globulin for some exposures; exposed newborn needs birth dose vaccination and immune globulin as soon as possible. All infants should receive birth dose of vaccine.
• Hepatitis A: it is inactivated virus vaccine. There is no increased risk of disease during pregnancy. International travelers, pre-exposure and post-exposure for women at risk of infection should be considered before vaccination. Dose schedule - two-dose schedule 6 months apart.

III. Inactivated Bacterial Vaccines:

These vaccines are not routinely recommended during pregnancy and should be individualized. The various vaccines in this category are:

• Pneumococcus: it is a polyvalent polysaccharide vaccine. There is no increased risk of the disease during pregnancy and there is no increase in severity of disease. Risk from disease to fetus or neonate is unknown, but depends on maternal illness. Risk from immunizing agent to fetus is none reported. This vaccine is recommended for women with asplenia, metabolic, renal, cardiac, pulmonary diseases, smokers, and immunosuppressed patients. Indications are not altered by pregnancy. Dose schedule - in adults, one SC or IM dose only; consider repeat dose in 6 years for high-risk women.
• Meningococcus: it is a quadrivalent polysaccharide vaccine. The disease has significant morbidity and mortality; not altered by pregnancy. Risk from disease to fetus or neonate is unknown, but depends on maternal illness. Indications for vaccination are not altered by pregnancy; vaccination recommended in unusual outbreak situations. Dose schedule - one SC dose; public health authorities should be consulted.
• Typhoid: it is killed or live attenuated virus oral bacterial vaccine. The disease has significant morbidity and mortality; not altered by pregnancy. Risk from disease to fetus or neonate is unknown. This vaccination is not recommended routinely except for close, continued exposure or travel to endemic areas. Dose schedule - killed primary vaccine: two injections SC at least 4 weeks apart. Booster vaccine: single dose SC or ID (depending on type of product). Booster schedule is not yet determined. Oral vaccine is preferred.
• Anthrax: it is preparation from cell-free filtrate of B anthracis; no dead or live bacteria. The disease has significant morbidity and mortality; not altered by pregnancy. Risk from disease to fetus or neonate is unknown but depends on maternal illness. Teratogenicity of vaccine is theoretical. The anthrax vaccine is not routinely recommended unless pregnant women work directly with B anthracis, imported animal hides, potentially infected animals in high incidence areas (not United States) or military personnel deployed to high-risk exposure areas. Dose schedule - six-dose primary vaccination SC, then annual booster vaccination.

IV. Toxoids:

Updating of immune status of tetanus should be part of antepartum care. Immunization for tetanus during pregnancy is safe. Risk from immunizing agent to fetus is none confirmed. Indication for immunization during pregnancy is lack of primary series of vaccination or no booster within past 10 years.

• Tetanus - Diphtheria (Td): combined tetanus-diphtheria toxoids are preferred; adult tetanus-diphtheria formulation. The disease has severe morbidity; tetanus mortality 30% diphtheria mortality 10% unaltered by pregnancy. Neonatal tetanus mortality is about 60%. Risk from immunizing agents to fetus is none confirmed. Dose schedule - Primary: two-doses IM at 1-2 month interval with a third dose 6-12 months after the second. Booster: single dose IM every 10 years after completion of primary series.

V. Specific Immune Globulin:

Their utilization during pregnancy depends on exposure and consultation with Advisory Committee on Immunization Practices (ACIP) is suggested. The vaccines in this category are:

• Hepatitis B: it is known as Hepatitis B Immune Globulin and can be used in post-exposure prophylaxis in pregnancy. The possibility of the disease to be severe in third trimester is high. There is possible increase in abortion rate and preterm births. Neonatal hepatitis can occur and there is high risk of carrier-state in newborn. This is usually given with hepatitis B virus vaccine; exposed newborn needs immediate post-exposure prophylaxis. Dose schedule - depends on exposure; consult (ACIP).
• Rabies: it is known as Rabies Immune Globulin and given for post-exposure prophylaxis. Rabies is nearly 100% fatal and the disease is not altered by pregnancy. Risk from disease to fetus or neonate is determined by maternal disease. It is used in conjunction with rabies killed virus vaccine. Dose schedule - half dose at injury site, half dose in deltoid.
• Tetanus: it is known as Tetanus Immune Globulin and given for post-exposure prophylaxis. It is used in conjunction with tetanus toxoid. Tetanus has severe morbidity and mortality about 60%. Neonatal tetanus mortality is 60%. Dose schedule - one dose IM.
• Varicella: it is known as Varicella-Zoster Immune Globulin. This should be considered for healthy pregnant women exposed to varicella to protect against maternal, not congenital infection. It is also indicated for newborns of women who developed varicella within 4 days before delivery or 2 days following delivery; approximately 90-95% of adults are immune to varicella. It is not indicated for prevention of congenital varicella. Varicella has increased risk of severe varicella pneumonia in pregnancy and it can cause congenital varicella with increased mortality in neonatal period. Very rarely causes congenital defects. Dose schedule - one dose IM within 96 hours of exposure.

VI. Standard Immune Globulin:

• Hepatitis A: it is known as Standard Immune Globulin. Post-exposure prophylaxis is the most common indication but hepatitis A virus vaccine should be used with hepatitis A immune globulin. The risk of disease to the pregnant woman is possible increased severity during third trimester. It probably increases in abortion rate and preterm birth. Possible transmission to neonate at delivery is present if woman is incubating the virus or is acutely ill at that time. Immune globulin should be given as soon as possible and within 2 weeks of exposure. Infants born to women who are incubating the virus or are acutely ill at delivery should receive one dose of 0.5 mL as soon as possible after birth. Dose schedule - 0.02 mL/kg IM in one dose of immune globulin.

Vaccines against sexually transmitted HPV are currently being developed for both treatment of the infection and prevention of cervical cancer. Therapeutic vaccines aim to augment the host's cell-mediated immunological response to infected cells, whereas prophylactic vaccines induce antibody formation. Particular targets include the HPV-11, HPV-16 and HPV-18 strains, which are known to cause cervical cancer. Studies are scheduled to continue, and no product is yet available to the public for vaccination. Other immunizations are being developed as well. Vaccines that may be available later this decade include meningococcal conjugate vaccine, acellular pertussis vaccine for adults, Herpes Zoster vaccine, nicotine vaccine and Staphylococcus aureus vaccine.

VIII. Human Papillomavirus (HPV) Vaccine:

The HPV vaccine is most effective when administered to girls and women before the onset of sexual activity. While the FDA has approved for girls and women ages 9 to 26, the federal Advisory Committee on Immunization Practices recommends that girls routinely receive vaccine between the ages 11 and 12. Vaccination is also recommended for women up to age 26, regardless of sexual activity. Women who previously have had abnormal cervical cytology, genital warts, or precancerous lesions can be vaccinated, but the effects on this population are unknown. Those with suppressed immune systems also can be vaccinated, although the protection may be less than that for patients with normal immune function. The HPV vaccine is not a treatment for current HPV infection or genital warts.

Data on vaccination in pregnancy is limited; therefore, vaccination during pregnancy should be delayed until after completion of pregnancy. If a woman discovers she is pregnant during the vaccine schedule, she should delay finishing the series until after she gives birth. Women who are breastfeeding can receive the vaccine.

Dose schedule: three doses are needed. Dose #2 is given 4-8 weeks after dose #1, and dose #3 is given 6 months after dose #1 (at least 10 weeks after dose #2). The vaccine should be given IM in the deltoid. Contraindication: previous anaphylactic reaction to this vaccine or to any of its components.

Editor's Note

Although immunization has had a profound effect on childhood infectious disease, thousands of adults die from vaccine-preventable illness each year. Women in particular can benefit from appropriate vaccination practices.

Resources

1. National Immunization Program
2. Traveler's Health: National Center for Infectious Disease
3. The Group on Immunization Education of the Society of Teachers of Family Medicine
4. Immunization Action Coalition

Published: 6 August 2009