Did you know babies routinely get antibodies to anything you’ve been vaccinate against? Babies get temporary disease protection from you in this way. When you are vaccinated, your body has an immune response that makes antibodies to what you were vaccinated against. Antibodies are then secreted in breast milk to your baby. The type and quantity of these antibodies, and whether they provide any protection for baby after they are swallowed, are dependent on the vaccine received and maternal factors that influence immune system function such as genes, age and health.
Antibodies in breast milk have not been shown to reduce baby’s response to their own immunizations. However, some studies suggest that breast milk may improve baby’s immune response to some of the vaccines they receive.
If you do decide to be vaccinated while breastfeeding, there is no need to pump and dump your milk. Or to stop breastfeeding for any amount of time. When considering the vaccine, or any medication, most want to know whether a dangerous amount of a substance will be filtered into our milk and cause harm to our baby. For most drugs, so little gets to the baby that there’s really very little theoretical risk. Even if a drug or vaccine does end up in breastmilk, anything that goes through breastmilk also then has to go through baby’s gut before reaching baby’s bloodstream. The mRNA molecules in the Pfizer or Moderna vaccines, if they made it into your milk, would have to survive baby’s stomach acid first.
While breastfeeding, it is highly unlikely that an intact lipid from the vaccine would enter your blood stream and be passed directly into your milk. If it does, it is even less likely that either the intact nanoparticle or mRNA could be transferred into your milk. In the unlikely event that mRNA is present in your milk, it would first go through baby’s digestive system and would be unlikely to have any biological effects. The vaccine is supposed to trigger an immune response in your body. It helps your body recognize the virus when you’re exposed and fights the virus early, reducing the severity and length of illness. Once your immune system recognizes the SARS-CoV-2, the virus that causes Covid-19, antibodies are made to protect you and those antibodies may pass into the breastmilk. Researchers have already found Covid antibodies in the breastmilk of previously infected women, though they don’t know yet how much protection these antibodies give babies.
Choosing to be vaccinated is a personal risk/benefit decision to be made between you and your health care providers. If you do chose to be vaccinated with the COVID vaccines, there is no need to pump and dump for concerns of your milk harming your baby.