Yes. There is a wealth of evidence that breastfeeding reduces the risk of babies developing infectious diseases. There are numerous live constituents in human milk, including immunoglobulins, antiviral factors, cytokines and leucocytes that help to destroy harmful pathogens and boost the baby’s immune system.
There is currently no evidence that Covid-19 can be passed to the baby through breastfeeding. There is also evidence that mothers with Covid-19 pass their antibodies to their baby through breastmilk, thereby giving protection to their baby.
(Source: https://www.unicef.org.uk/babyfriendly/covid-19/ )
If you are breastfeeding or giving your expressed milk, you can have any of the three vaccines currently available in the UK (Astra Zeneca, Pfizer/BioNTech or Moderna), as long as you meet the other conditions for receiving the vaccine (as set out by the JCVI and MHRA). As with other vaccines, there is no evidence that anything other than antibodies passes into your breast milk. These antibodies are not harmful to your baby, and may give some protection against the virus. There is no need to avoid giving your baby your breast milk directly after you have the vaccine, either by missing breastfeeds, or expressing and dumping milk.
The JCVI has recommended that the vaccines can be received whilst breastfeeding. This is in line with recommendations from the USA and the World Health Organization.