Immunisations in pregnancy
Why are immunisations in pregnancy important?
Vaccines work by stimulating your immune system to produce antibodies, which can fight infections and prevent you from becoming ill. Even if you are healthy, when you are pregnant, your body has a harder time fighting infections than when you are not pregnant. Healthy, pregnant women are able to mount a similar response to vaccines as healthy, non-pregnant women. It is important to understand that with some immunisations the goal is to enable the transfer of maternal antibodies to your baby before birth to achieve maximum passive neonatal immunity during the first few months.
Some immunisations are safe to give during pregnancy, while others have to be given at least a month before pregnancy. Certain immunisations are recommended for all women, while others are only recommended for women at high risk of becoming infected during pregnancy.
A “live vaccine” is made from live viruses or bacteria that have been weakened and they cause the body to make protective antibodies that provide long-lasting protection after a single dose. Live vaccines are not routinely given during pregnancy.
An ‘inactivated vaccine” is made from viruses or bacteria which have been killed and cannot cause the disease that it is given to prevent. These inactivated vaccines may require periodic “boosters” and may require multiple doses. Pregnant women could therefore be susceptible although they have been previously immunised. Inactivated vaccines have not been shown to cause birth defects or pregnancy complications.
Immune globulins (antibodies) are sometimes given to prevent or reduce the severity of certain diseases during pregnancy. This is a form of passive immunity and there is no known risk for the baby.
Is it safe to have an immunisation during pregnancy?
When immunisations are considered during pregnancy, the benefits to both the mother and the baby should outweigh the risks. There is no evidence of harm to pregnant women and their babies from the administration of inactivated vaccines. However, live vaccines that are considered safe in children and adults may be harmful to a developing fetus.
Thimerosal is a preservative and is found in some vaccines in very small amounts. Some authors have linked autism to childhood vaccine exposure and thimerosal. However, there has been no evidence, even in large studies, of any harmful effects and pregnant women can safely receive vaccines containing thimerosal.
Why is flu immunisation important in pregnancy?
Flu is a highly infectious disease that spreads through coughs and sneezes of people who carry the disease. Based on the data from seasonal influenza/flu and from the influenza pandemics, pregnant women with flu are more likely to develop severe illnesses and even fatalities, than the general population. The increased severity of influenza in pregnant women is thought to be related to the normal physiological changes that occur during pregnancy in a woman’s circulation system, as well as her immune system.
Having the flu while pregnant does not in itself cause birth defects, although a high fever could affect the developing baby. Women who get very sick from flu during pregnancy may be at an increased risk of pregnancy complications. New born babies who get flu are also at an increased risk of complications.
Because of the increased severity of influenza in pregnancy, inactivated influenza vaccine is recommended for al pregnant women, regardless of the stage of pregnancy. Vaccinating the mother and other care givers, may help protect the baby from getting flu after birth since infants cannot receive the flu immunisation until they are 6 months old.
When should I get a flu immunisation?
To provide protection through the flu season, it is important to receive the vaccine as soon as it becomes available and in South Africa it is usually available by March. Protection begins about 2 weeks after you get the flu shot and lasts for about 6-8 months. It is therefore necessary to receive the seasonal flu shot with every pregnancy in order to protect yourself from the current flu virus.
Studies have shown that the flu vaccine is safe during any stage of pregnancy, even from the first few weeks. The risk of flu increases in the later stages of pregnancy and it is never too late to get vaccinated.
Why is Whooping cough immunisation important in pregnancy?
Pertussis (also called whooping cough) is a bacterial disease that usually begins with symptoms similar to those of the common cold. Whooping cough is a highly infectious disease that can cause serious and sometimes life threatening complications in babies, especially in the first 6 months of life. Almost half of the babies who get whooping cough, end up in hospital. Newborns are also at greater risk of complications and it can lead to death. If a person is not given a vaccine, there is about an 80% chance that a person living in a household with an infected person will catch pertussis. Many babies are therefore infected with whooping cough from family members who are unaware that they have the disease.
The Tdap vaccine provides protection against tetanus, diphtheria and pertussis for teens and adults. Childhood vaccination for these diseases however does not provide lifelong protection. In order to protect babies against pertussis it is important that everyone around them is vaccinated. In the past, Tdap wasn’t recommend during pregnancy because pertussis was uncommon in adults, but this is no longer the case. Pregnant women who receive the whooping cough immunisation produce antibodies to whooping cough and this is passed through the placenta to your baby.
Tetanus and diphtheria can both be deadly to pregnant women and can cause loss of the baby. This is however rare today. The Tdap vaccine will also serve as a booster vaccination against tetanus and diphtheria for those women in whom 10 years has elapsed since the last Td booster.
The Tdap vaccine is an inactivated non-infectious vaccine and safe in pregnancy with no known
adverse effects for mother or baby. The brand names of Tdap are Boostrix® or Adacal®.
When should I get a whooping cough immunisation?
Receiving the shot in the third trimester (between 27 -36 weeks) is recommended, so the baby can get as many antibodies as possible. The Tdap vaccine can safely be given to breastfeeding mothers if they have not previously been vaccinated with Tdap. Note that this protection will wear off over time and babies should still receive their whooping cough vaccine at 2 months.
It is recommended getting the Tdap vaccine in every pregnancy. If the mother, father, household members and other adult caregivers get the vaccine, it will also lower the chance of the baby being exposed to pertussis.
Pregnant women are the only population in whom repeated Tdap immunisation is recommended; repeated immunisation is not recommended for household contacts.
What other immunisations should be considered in pregnancy?
The Hepatitis B vaccine is recommended for pregnant women who live with someone infected with hepatitis B and also for women who started the immunisation series, but have not completed it before falling pregnant.
The hepatitis A immunisation is also recommended for those at risk, while the indications for meningococcal disease (meningitis) are not altered by pregnancy.
What about measles and chickenpox?
As with other live vaccines, varicella (chicken pox) vaccine should not be administered to pregnant women. If pregnant woman is exposed to varicella and is not immune, then varicella-zoster immunoglobulin is indicated as post-exposure prophylaxis.
The measles, mumps, rubella (MMR) vaccine, a live-attenuated vaccine, should not be given to pregnant women. If a pregnant woman is exposed to measles and is not immune, then intravenous globulin is indicated as post-exposure prophylaxis. It is important that pregnant women without evidence of immunity to rubella (or measles) should receive the MMR vaccine postpartum.
What about anti-D?
Rhesus disease of the newborn can largely be prevented by having an anti-D immunoglobulin immunisation. The anti-D immunoglobulin neutralises any RhD positive antigens that may have entered the mother’s blood during pregnancy. If the antigens have been neutralised, the mother’s blood won’t produce antibodies that could potentially harm the baby. This topic will be discussed separately in the future.