Immunization in pregnancy and breastfeeding: Canadian Immunization Guide

For health professionals

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Notice

This chapter has not yet been updated with the following statement from the National Advisory Committee on Immunization (NACI):

• May 24, 2024: Interim guidance on the use of Imvamune^® in the context of a routine immunization program

Last partial content update: October 2024

This chapter has been updated with guidance from the following statement from the National Advisory Committee on Immunization (NACI):

• May 17, 2024: Statement on the prevention of respiratory syncytial virus disease in infants

This information is captured in the table of updates.

Last complete chapter revision: April 2018

On this page

• Introduction
• Benefits of immunization in pregnancy for pregnant women and pregnant individuals
• Safety of immunization in pregnancy for pregnant women and pregnant individuals
• Benefits of immunization in pregnancy for the fetus and infant
• Safety of immunization in pregnancy for the fetus and infant
• Immunization during pregnancy
• Immunization of household contacts of pregnant women and pregnant individuals
• Immunization during breastfeeding
  • Table 1: Summary of recommendations for immunization in pregnancy and breastfeeding - non-live vaccines
  • Table 2: Summary of recommendations for immunization in pregnancy and breastfeeding - live vaccines
• Selected references

Please note: The Public Health Agency of Canada (PHAC) recognizes that not all people giving birth or breastfeeding will identify as women or mothers. The writing in this chapter uses a gender additive approach where the term 'woman' is used alongside gender neutral language. This is intended to demonstrate a commitment to redress the historic exclusion of trans and non-binary people, whilst avoiding the risk of marginalising or erasing the experience of women within the health care environment. However, in line with best practice, it is recognized that when discussing or caring for individuals in a one-on-one capacity, language and documentation should reflect the gender identity of the individual.

Introduction

Pregnancy provides an opportunity for health care providers to evaluate immunization status. Pregnancy is associated with an altered immune response and, for some infectious diseases, an increased risk of infection and an increased risk of severe outcomes once infected. The fetus, neonate and young infant can also be affected by infections that can result in congenital abnormalities, impaired fetal growth or severe neonatal illness.

One of the challenges of developing guidelines for immunization during pregnancy and breastfeeding is the scarcity of studies to support evidence-based recommendations. Only a few methodologically robust studies of vaccine administration in pregnancy and breastfeeding exist; most safety data available are derived from active surveillance or from registries where outcomes are passively reported.

When considering vaccination in pregnancy, it is important to distinguish between live and non-live vaccines. There is no theoretical reason to suspect that non-live vaccines are associated with an increased risk of adverse events when administered during pregnancy and data from active and passive surveillance systems confirm safety for several vaccines. Live vaccines should generally not be given during pregnancy because of the theoretical risk of harm to the fetus if transmission of the vaccine strain to the fetus occurs.

The objective of vaccination during pregnancy is to protect the pregnant woman and pregnant individual and the fetus and newborn. Even though pregnancy is an immunologically altered state, response to vaccines is adequate. Clinical trials of pertussis, tetanus toxoid, and non-live polio vaccine administered during pregnancy have demonstrated usual adult immunologic responses.

Ideally, the immunization status of individuals of child-bearing age should be reviewed regularly and vaccines updated as needed. Live vaccines, for example, can be given during reproductive planning, prior to conception, with the advice to avoid pregnancy for at least 28 days following immunization.

Benefits of immunization in pregnancy for pregnant women and pregnant individuals

Vaccines recommended for the protection of pregnant women and pregnant individuals' health include:

• non-live influenza vaccine
• mRNA COVID-19 vaccine
• acellular pertussis vaccine (given as tetanus toxoid, diphtheria toxoid, acellular pertussis vaccine)
• hepatitis B vaccine if susceptible and with ongoing exposure risks
• hepatitis A vaccine if indicated
• meningococcal vaccine in an outbreak setting or post-exposure, or if indicated by medical condition
• pneumococcal vaccine if indicated by medical, environmental or living conditions
• any other non-live vaccine if indicated by exposure (e.g., rabies), travel (e.g., non-live typhoid vaccine) or by medical condition (e.g., asplenia).

Refer to the vaccine-specific chapters in Part 4 for additional information.

Safety of immunization in pregnancy for pregnant women and pregnant individuals

Non-live vaccines are considered safe when administered in pregnancy. Reactions following vaccination with non-live vaccines are usually limited to the injection site. No increase in anaphylactic reactions that might induce preterm labour have been observed following immunization with non-live vaccines. With the possible exception of RSVpreF vaccine, no events that might induce preterm labour have been observed following immunization with non-live vaccines.

Benefits of immunization in pregnancy for the fetus and infant

The beneficial effects of immunization during pregnancy for the fetus as well as the newborn infant have been well documented. Vaccination during pregnancy protects pregnant women and pregnant individuals from vaccine-preventable diseases that may otherwise be acquired and be transmitted to the fetus or infant. In addition, protective concentrations of antibodies are transferred to the fetus transplacentally, resulting in increased infant protection in the early postnatal period. The majority of transplacental antibody transfer occurs during the third trimester and the half-life of these antibodies in the newborn is typically 4 to 6 weeks. Transplacentally acquired antibody concentrations progressively decrease during the first year of life.

Safety of immunization in pregnancy for the fetus and infant

There is no theoretical reason to anticipate adverse events in the fetus or infant following vaccination with non-live vaccines during pregnancy. There are no published data indicating that currently authorized non-live vaccines are teratogenic or embryotoxic. Currently, there are no published data confirming a causal relationship between any authorized non-live vaccine and specific adverse pregnancy outcomes.

The National Advisory Committee on Immunization (NACI) has concluded that vaccines that contain thimerosal (now only in multi-dose vials of influenza vaccine and hepatitis B vaccine) are safe in pregnancy and should be used if indicated.

In general, live attenuated viral or bacterial vaccines are contraindicated in pregnancy, as there is a theoretical risk to the fetus; however, when benefits outweigh this theoretical risk, vaccination with a live attenuated vaccine may be considered (e.g., during a rubella outbreak).

Immunization during pregnancy

Table 1 and Table 2 provide a summary of recommendations for immunization during pregnancy.

Recommended vaccines

mRNA COVID-19 vaccine

Vaccination against COVID-19 is particularly important in pregnancy. Compared to non-pregnant people, COVID-19 infection in pregnancy is associated with increased risk of hospitalization and admission to an intensive care unit. COVID-19 infection during pregnancy is also associated with an increased risk in the neonate of preterm birth, low birth weight and admission to a neonatal intensive care unit. Vaccination helps to protect the pregnant woman and pregnant individual and lowers the risk of hospitalization for their newborn. Safety data from COVID-19 immunization registries have not revealed any maternal or neonatal safety signals.

Refer to COVID-19 vaccines in Part 4 for additional information.

Non-live influenza vaccine

All pregnant women and pregnant individuals, at any stage of pregnancy, should receive a non-live influenza vaccine that is, inactivated influenza vaccine (IIV-SD or IIV-cc), or recombinant influenza vaccine (RIV). When a pregnancy extends over 2 influenza seasons, 2 doses of influenza vaccine may be received during the course of the pregnancy (one in each influenza season). Influenza infection is associated with an increased risk of influenza-associated morbidity and hospitalization during pregnancy as well as adverse neonatal outcomes, including late pregnancy loss and stillbirth. Influenza vaccination during pregnancy has been shown to protect the pregnant person from influenza and its complications. It also protects infants for the first few months of life from influenza and influenza-related hospitalization.

There is a robust body of evidence demonstrating the safety of most non-live influenza vaccines used during pregnancy. No potential safety signal has been identified although there are limited published clinical data pertaining to safety of vaccination with RIV4 during pregnancy to inform vaccine-associated risks for this population. Active surveillance following influenza vaccination during pregnancy has not shown evidence of harm to pregnant women or pregnant individuals or fetus. Although the cumulative sample size of these studies is relatively small, particularly for immunization in the first trimester, passive surveillance has not raised any safety concerns, despite widespread use of influenza vaccine in pregnancy over several decades. Surveillance following the use of both adjuvanted and unadjuvanted pandemic H1N1 influenza (pH1N1) vaccine in more than 100,000 pregnant women in Canada and almost 500,000 pregnant women in Europe did not reveal any safety concerns; however, the adjuvanted influenza vaccine available in Canada (IIV3-Adj) is not authorized for people of reproductive age.

During the influenza season, if influenza vaccine was not received during pregnancy, it should be given as early as possible post-partum, preferably before discharge from hospital.

Refer to Influenza vaccines in Part 4 for additional information.

Pertussis vaccine (given as tetanus toxoid, diphtheria toxoid, acellular pertussis vaccine)

All pregnant women and pregnant individuals should be given tetanus toxoid, diphtheria toxoid, acellular pertussis (Tdap) vaccine during every pregnancy, irrespective of their Tdap immunization history. Immunization with Tdap in pregnancy has been shown to be safe and effective in preventing neonatal and infant pertussis infection. High levels of antibody are transferred to the fetus, protecting the newborn from pertussis during the first two months of life when the morbidity and mortality from pertussis infection is highest. The vaccine should ideally be provided between 27 and 32 weeks of gestation. Immunization between 13 and 26 weeks of gestation may be considered in situations where there may be an increased risk of preterm delivery. Although it is preferable that immunization is administered in sufficient time before birth (i.e., 4 weeks) to allow optimal transfer of maternal antibodies, if not given earlier it should be given at any time until delivery, to provide partial protection and prevent pertussis infection in pregnancy and subsequent transmission to the newborn.

Administration of tetanus toxoid in pregnancy has been shown to prevent neonatal tetanus infection and death in countries with high rates of neonatal tetanus.

Refer to Pertussis (whooping cough) vaccines, Tetanus toxoid, and Diphtheria toxoid chapters in Part 4 for additional information.

Hepatitis B (HB) vaccine

All pregnant women and pregnant individuals should be routinely tested for hepatitis B surface antigen (HBsAg) in each pregnancy (unless they are already known to be hepatitis B virus (HBV) immune or carriers of HBV), so that the newborn can be given HB prophylaxis if indicated.

Acute HB infection in a pregnant woman or pregnant individual may result in severe disease and chronic infection in the infant. A pregnant woman or pregnant individual who has no markers of HB infection (HB antibody and HbsAg negative) but who is at high risk of HB acquisition should be offered a complete HB vaccine series at the first opportunity during the pregnancy and should be tested for antibody response. Immunization with HB vaccine in pregnancy has been shown to be safe.

Refer to Hepatitis B vaccines in Part 4 for additional information.

Vaccines that may be indicated

Haemophilus influenzae type b (Hib) vaccine

Hib vaccine should be considered in pregnancy if indicated for a medical condition at high risk for Hib disease. Although Hib vaccine has not been studied in pregnancy, there is no theoretical reason to suspect that adverse events to pregnant women and pregnant individuals or infants will occur. Refer to Haemophilus influenzae type b (Hib) vaccines in Part 4 and Immunization of immunocompromised persons and Immunization of persons with chronic diseases in Part 3 for additional information.

Hepatitis A (HA) vaccine

Hepatitis A can cause severe disease in pregnancy, and the vaccine should be considered for pregnant women and pregnant individuals when indicated for post-exposure prophylaxis, for travel to endemic areas or for other exposure risks. The efficacy and safety of hepatitis A vaccines given during pregnancy has not been studied in clinical trials, but there is no evidence of, or theoretical reason to suspect an increased risk of adverse events to pregnant women and pregnant individuals or the infants will occur. Refer to Hepatitis A vaccines in Part 4 for additional information.

Human papillomavirus (HPV) vaccine

Pregnant women and pregnant individuals who are unvaccinated against HPV remain at risk of HPV infection and HPV-related morbidity during their pregnancy. Maternal HPV infection might increase the risk of pregnancy complications, such as spontaneous abortion, preterm birth, preeclampsia, intrauterine growth restriction, premature rupture of membranes, and fetal death. The nonavalent (9vHPV) vaccine can be offered in pregnancy. Current evidence suggests that there is no increased risk of adverse pregnancy or fetal outcomes linked to HPV vaccination during pregnancy.

Refer to Human Papillomavirus (HPV) vaccines in Part 4 for additional information.

Meningococcal vaccine

Conjugate quadrivalent meningococcal vaccine and meningococcus B vaccine should be considered in pregnancy, if indicated in circumstances such as a medical condition at high risk for meningococcal disease; travel to a high risk area; post-exposure prophylaxis; or during an outbreak. Although these vaccines have not been studied in pregnancy, there is no theoretical reason to suspect that adverse events to pregnant women and pregnant individuals or infants will occur.

Refer to Meningococcal vaccines in Part 4 and Immunization of immunocompromised persons and Immunization of persons with chronic diseases in Part 3 for additional information.

Pneumococcal vaccine

Pregnant women and pregnant individuals at high risk of invasive pneumococcal disease can, if indicated, be vaccinated with the appropriate pneumococcal vaccines. There is no evidence to suggest a risk to the infant, fetus or to the pregnancy from immunization with pneumococcal vaccine in pregnancy.

Refer to Pneumococcal vaccines in Part 4 and Immunization of immunocompromised persons and Immunization of persons with chronic diseases in Part 3 for additional information.

Poliomyelitis vaccine

Non-live poliomyelitis vaccine (IPV) may be considered for non-immune pregnant women and pregnant individuals who are at increased risk of exposure to wild poliovirus. Limited data have not revealed an increased risk of adverse events associated with IPV vaccine administered in pregnancy and there is no theoretical reason to suspect an increased risk of adverse events.

Refer to Poliomyelitis vaccines in Part 4 for additional information.

Respiratory syncytial virus (RSV) vaccine

RSV infection is a major cause of lower respiratory tract illness among infants in their first RSV season in Canada. It can have serious complications, including hospitalization and intensive care unit admission, especially for infants with certain medical conditions. To prevent severe RSV disease in infants, RSV monoclonal antibodies are recommended. Where these are not available, a pregnant woman or pregnant person, in conversation with their care provider, might consider immunization with RSVpreF (Abrysvo^TM) vaccine in advance of, or during, the RSV season.

RSVpreF vaccine should be given at 32 through 36 weeks gestation to allow time for the development of an immune response and passive antibody transfer to the fetus before birth. Infants whose gestational parent received RSVpreF vaccine do not need nirsevimab unless the infant meets the medical criteria for increased risk of severe RSV disease or the infant is born less than 2 weeks after administration of RSVpreF.

The efficacy of RSVpreF vaccine in preventing RSV infection in pregnant women and pregnant people has not been evaluated.

Overall, RSVpreF is well tolerated in pregnant women and pregnant people. Some studies found an increase in preterm births among RSVpreF vaccine recipients compared to placebo recipients. At this time, data are insufficient to definitively exclude a causal relationship between the RSVpreF vaccine and preterm birth. The prescribed timing for RSV vaccine administration further minimizes the indeterminate risk of preterm birth.

Refer to Respiratory syncytial virus (RSV) vaccine in Part 4 for additional information.

Rabies vaccine

If a pregnant woman or pregnant individual has had a potential exposure to rabies, since rabies is invariably fatal, post-exposure prophylaxis should be provided.

If pre-exposure prophylaxis is indicated, it is prudent to delay immunization until after pregnancy unless there is an increased risk of rabies exposure during the pregnancy, in which case the vaccine should be given. Limited data have not shown an increased risk of adverse events in pregnancy, and there is no theoretical reason to suspect that adverse events will occur.

Refer to Rabies vaccines in Part 4 for additional information.

Travel vaccines

Japanese encephalitis (JE) acquired during pregnancy carries the risk of intrauterine infection and miscarriage. Pregnant women and pregnant individuals who must travel to areas where the risk of JE infection is high should be immunized as the risk of disease outweighs the unknown risk of vaccination. Non-live typhoid vaccine should be considered when indicated for travel to endemic areas if risk factors for severe disease are present. Cholera and enterotoxigenic Escherichia coli (ETEC) travellers' diarrhea vaccine should be considered for those at risk of severe disease if infection occurs.

These are non-live vaccines and there is no theoretical reason to suspect increased risk of post-immunization adverse effects in pregnant women and pregnant individuals or the fetus. However, because these vaccines have not been studied in pregnancy, administration should be considered only in high risk situations after evaluation of the benefits and risks. Live typhoid vaccine should not be used in pregnancy.

Refer to vaccine-specific chapters in Part 4 for additional information.

Immunoglobulin

Immunoglobulin products may be administered in pregnancy as required for pre- or post-exposure prophylaxis (measles, varicella, HA, HB, tetanus, rabies) or as replacement therapy. There is no known or theoretical risk to the fetus or to a pregnant woman or pregnant individual from their administration.

Vaccines not recommended

Recombinant herpes zoster vaccine (RZV)

This vaccine should be used with precaution in those who are pregnant (as there are no data on its use in this population), or breastfeeding (as the effect on breast-fed infants of vaccination in those who are breastfeeding has not been studied). The safety and efficacy of RZV in pregnant women and pregnant individuals younger than 18 years of age has not been studied.

Refer to Herpes zoster (shingles) vaccine in Part 4 for additional information.

Generally contraindicated vaccines

Administration of live attenuated vaccines is generally contraindicated in pregnancy because there is a theoretical risk of infection of the fetus.

Measles-mumps-rubella (MMR) vaccine

Although MMR vaccine is generally contraindicated in pregnancy, in situations when potential benefits may outweigh risks, such as during measles or rubella outbreaks, vaccination may be considered. Rubella infection during pregnancy frequently gives rise to congenital rubella syndrome which can result in miscarriage, stillbirth or fetal malformations. Measles during pregnancy results in a higher risk of premature labour, spontaneous abortion and low birth weight infants. To date, there is no evidence demonstrating a teratogenic or other adverse effect from MMR vaccine given during pregnancy. Inadvertent immunization with MMR vaccine is therefore not a reason for pregnancy termination.

Pregnant women and pregnant individuals without documented laboratory evidence of rubella immunity or prior immunization with a rubella-containing vaccine should be serologically screened for rubella antibodies. Those who are seronegative should receive MMR vaccine, with the first dose given in the immediate post-partum period before discharge from hospital (unless they have received Rh immunoglobulin (RhIg) or other blood products recently). If indicated for measles or mumps protection, a second dose of MMR should be given 4 weeks or more after the first. For post-partum MMR immunization of women and individuals who received RhIg or other blood products, refer to Blood products, human immunoglobulin and timing of immunization in Part 1.

Refer to Measles vaccines, Mumps vaccines, and Rubella vaccines in Part 4 for additional information including guidance on post-exposure prophylaxis with measles immunoglobulin for susceptible pregnant women exposed to measles.

Monovalent varicella vaccine

Monovalent varicella vaccine, a live attenuated vaccine, is contraindicated in pregnancy because there is a theoretical risk to the fetus; however, there is no evidence to demonstrate a teratogenic or other adverse event from varicella vaccination in pregnancy. Inadvertent immunization with varicella vaccine is not a reason for pregnancy termination.

Pregnant women and pregnant individuals without documented laboratory evidence of varicella immunity or prior immunization with 2 doses of varicella vaccine should be serologically screened for varicella antibodies. Those who are seronegative should receive univalent varicella vaccine in the immediate post-partum period prior to hospital discharge unless they have received Rh immunoglobulin (RhIg). A second dose should be given 4 weeks or more after the first. For additional information regarding post-partum MMR immunization of women or individuals who received RhIg or other blood products, refer to Table 1 in Blood products, human immunoglobulin and timing of immunization in Part 1.

Refer to Varicella (chickenpox) vaccines in Part 4 for additional information, including post-exposure prophylaxis with varicella zoster immunoglobulin for pregnant women and pregnant individuals exposed to varicella.

Yellow fever (YF) vaccine

Yellow fever virus can cause severe infection in pregnancy and transmission to the fetus has been reported. YF vaccine should be avoided in pregnancy unless benefit outweighs risk. Pregnant women and pregnant individuals should be considered for YF immunization only if they are travelling to an area at high risk of YF transmission, travel cannot be postponed and a high level of protection against mosquito exposure is not feasible. Since seroconversion rates following YF vaccine are lower during pregnancy, post-immunization serology may be considered. Studies including several hundred women who received YF vaccine during pregnancy, using both active and passive surveillance methods, have not shown significant adverse events. Inadvertent immunization with YF vaccine is therefore not a reason for pregnancy termination.

A waiver or Certificate of Medical Contraindication to Vaccination should be provided if a pregnant woman or a pregnant individual travels to a country that is not an area of high risk but requires documentation of YF vaccination. Refer to Yellow fever vaccine in Part 4 and to CATMAT's Statement on pregnancy and travel for additional information.

Other live vaccines

The use of other live attenuated vaccines during pregnancy must be evaluated on the basis of the individual risk and benefit. If an alternative non-live vaccine is available, such as in the case of influenza or typhoid vaccine, it should be used instead of a live attenuated vaccine.

No safety concerns have been identified with the use of live attenuated influenza vaccine (LAIV) in pregnancy, although there are more data on the safety of non-live influenza vaccines in pregnancy. There is also evidence that inactivated influenza vaccine has higher efficacy than LAIV in healthy adults. Inadvertent vaccination with LAIV during pregnancy should not be considered a reason to terminate pregnancy.

Bacille Calmette-Guérin (BCG) vaccine has not been studied in pregnant women or pregnant individuals and should not be given during pregnancy, although no harmful effects of BCG vaccination on the fetus have been observed.

First and second generation (live replicating) smallpox vaccines are contraindicated during pregnancy in non-emergency situations. They may be considered for a pregnant woman and pregnant individuals in the highly unlikely event of a high-risk exposure. The first and second generation smallpox vaccines have very rarely led to fetal vaccinia resulting in stillbirth or neonatal death. If a woman or a person becomes pregnant within 4 weeks after live replicating smallpox vaccination, they should be counselled regarding possible risk to the fetus.

Imvamune, a third generation (live attenuated, non-replicating) smallpox and mpox vaccine, was approved in 2020 for active immunization against smallpox, mpox virus and related orthopoxvirus infections and disease in adults 18 years of age and older determined to be at high risk for exposure. Data on Imvamune are limited in people who are pregnant, requiring an assessment of the benefits and the risks of its use in these populations.

There are limited safety data from the use of Ebola virus vaccine in pregnant and breastfeeding people, or in people who became pregnant after receiving the vaccine. The safety of the vaccine has not been established in pregnant or breastfeeding people. Nevertheless, given the seriousness of Ebola virus disease, the vaccine may be considered for pregnant individuals who have had an exposure to Ebola virus, occupational or otherwise, in Canada. Pregnancy should be avoided for 2 months following vaccination. Women of child-bearing potential should use an effective contraceptive method.

Refer to vaccine-specific chapters in Part 4 for additional information.

Immunization of household contacts of pregnant women and pregnant individuals

In general, pregnancy in a household does not affect immunization indications for any other members of the household. The exception is members of a household expecting a newborn during influenza season who are particularly recommended to receive influenza immunization to prevent transmission to the newborn. Pregnancy should be used as an opportunity to update immunization of susceptible household contacts, including live vaccines such as rotavirus, MMR, MMRV, varicella and LAIV.

In the unlikely event of a household contact being vaccinated using first or second generation smallpox vaccine, extreme precautions should be taken to prevent transfer of the vaccinia virus to unvaccinated household and other close contacts, pregnant or not. Such precautions can include isolation of the vaccinee from pregnant household contacts until the vaccine scab falls off.

Immunization during breastfeeding

Table 1 and Table 2 provide a summary of recommendations for immunization of breastfeeding women and breastfeeding individuals.

Immunization of breastfeeding women and breastfeeding individuals

In general, routinely recommended vaccines can be safely administered to breastfeeding women and breastfeeding individuals. There are limited data available regarding the effects of immunization of breastfeeding women and breastfeeding individuals on their infants; however, there have been no reported adverse events related to administration of routine vaccines. There is no evidence that immunization during breastfeeding will adversely influence the immune response of the vaccine recipient.

Annual influenza vaccination is recommended during breastfeeding if not given during that pregnancy. Either non-live influenza vaccines or LAIV can be administered to breastfeeding women and breastfeeding individuals. Women and individuals who are breastfeeding should also be vaccinated with COVID-19, Tdap, Td, hepatitis B, hepatitis A, HPV, pneumococcal, meningococcal, Hib, IPV, rabies, non-live typhoid, MMR, varicella, and cholera-traveller's diarrhea vaccines if indicated.

Japanese encephalitis (JE) vaccine has not been studied in breastfeeding. It is a non-live vaccine and there is no theoretical reason to suspect increased risk of adverse effects in breastfeeding women or breastfeeding individuals or their infants. Breastfeeding women and breastfeeding individuals who must travel to areas where the risk of JE infection is high should be immunized if the risk of disease outweighs the unknown risk of vaccination to the woman or individual and the breastfeeding infant.

Vaccines not recommended during breastfeeding

There are a few instances when vaccination is not recommended during breastfeeding. There have been three reported cases of probable transmission of YF vaccine strain virus from mothers to their infants through breastfeeding, resulting in meningoencephalitis in the infants. Therefore, in general, breastfeeding women and breastfeeding individuals should not be vaccinated. If, for entry to a country, a yellow fever vaccination certificate is required and there is no risk of acquiring yellow fever in the regions to be visited, a waiver or Certificate of Medical Contraindication to Vaccination should be sought. If travelling is to a highly endemic area and travel cannot be postponed, then the risk of vaccination causing disease in the breastfeeding infant should be weighed against the risk of yellow fever infection in the breastfeeding woman or breastfeeding individual and infant and the parents counselled about these risks.

Safety of oral typhoid vaccine in breastfeeding women and breastfeeding individuals is not known. Non-live typhoid vaccine should be used.

Caution should also be exercised when considering BCG vaccine because it is a live vaccine and it is not known whether BCG vaccine is excreted in human milk.

Breastfeeding women and breastfeeding individuals should not receive live replicating smallpox vaccine in non-emergency situations. It is not known whether the vaccine virus (vaccinia) is excreted in human milk. If smallpox vaccine must be given as post-exposure prophylaxis to a breastfeeding woman or breastfeeding individual, breastfeeding and other close contact with the baby should be avoided until the scab has separated from the vaccination site. Data on Imvamune, the third generation smallpox and mpox vaccine, are limited in people who are breastfeeding, requiring an assessment of the benefits and the risks of its use.

It is not known if the Ebola vaccine virus is secreted in human breast milk and there is no data available regarding the effects of vaccinating breastfeeding women and breastfeeding individuals on their infants. As a precaution, breastfeeding should be avoided, and infants should not have contact with maternal blood and body fluids, where feasible, for at least six weeks following vaccination, unless vaccination with Ebola virus vaccine is also indicated for the infant.

Refer to Immunization of travellers in Part 3 and to vaccine-specific chapters in Part 4 for additional information.

Immunization of breastfed infants

Infants who are breastfed should receive all recommended vaccines according to the routine immunization schedule. There is no evidence that the transfer of antibodies in human milk affects the efficacy of live attenuated vaccines in breastfed infants if these are given at the appropriate age.

Infants of breastfeeding women and breastfeeding individuals initiating monoclonal antibody treatment after delivery should be immunized according to routinely recommended schedules. Transfer of monoclonal antibodies through breast milk is limited, and the minimal quantities that are ingested are likely to be broken down in the infant's gastrointestinal tract.

For information on the immunization of infants exposed to immunosuppressive therapy in the womb, whether breastfeeding or not, refer to Immunization of immunocompromised persons in Part 3.

Selected References

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