Covid vaccines and pregnancy: coronavirus antibodies in breast milk can protect babies after jab

Babies can gain passive immunity to Covid-19 through immunoglobulins found in breast milk after vaccination, which could prevent them falling ill

While pregnant women were initially advised not to get the Covid-19 vaccine, guidance now states that the jab should be offered at the same time as people of the same age or risk group.

Under previous guidance, the vaccine has only been offered to pregnant women when their risk of exposure to the virus was high, such as health workers, or if a woman had underlying conditions placing her at higher risk of coronavirus-related complications.

The recommendation from the Joint Committee on Vaccination and Immunisation (JCVI) that all pregnant women can now have the jab comes following a study in the USA, which found no safety concerns during trials.

Babies can gain some protection against Covid-19 through breast milk if mothers have been vaccinated (Photo: Shutterstock)Babies can gain some protection against Covid-19 through breast milk if mothers have been vaccinated (Photo: Shutterstock)
Babies can gain some protection against Covid-19 through breast milk if mothers have been vaccinated (Photo: Shutterstock)

Around 90,000 pregnant women were vaccinated predominantly with the Pfizer or Moderna Covid-19 vaccines and no major safety concerns have been identified. Both the Pfizer and Moderna vaccines are the preferred jabs for women of any age who are pregnant and are receiving their first dose.

Anyone who has already received a dose and is offered a second while pregnant should be given the same vaccine, unless they had a serious side effect after their first jab.

While the JCVI is advising pregnant women to discuss the risks and benefits of being vaccinated against Covid-19 with their GP before getting the jab, there are many benefits in receiving the jab.

Covid-19 antibodies in breast milk

There is no evidence Covid-19 vaccines have any effect on fertility (Photo: Shutterstock)There is no evidence Covid-19 vaccines have any effect on fertility (Photo: Shutterstock)
There is no evidence Covid-19 vaccines have any effect on fertility (Photo: Shutterstock)

As well as protecting women from Covid-19, being vaccinated against the disease also poses benefits for babies.

A study conducted at Providence Portland Medical Center in the US found that breastfeeding mums could protect their babies through breast milk if they are vaccinated against coronavirus.

The small-scale research, published in medRxiv, assessed six lactating women who were vaccinated with either the Pfizer or Moderna vaccines from December 2020 to January 2021, all of whom had received two doses at 21 or 28 intervals.

Researchers collected breast milk samples before the first vaccine dose, plus at 11 additional time points, with the last sample taken two weeks after the second vaccine dose.

Findings showed that by day seven after the first dose, the breast milk samples had developed substantial IgG and IgA immunoglobulins against Covid-19.

The antibody levels dipped slightly in the weeks before the second dose, but rose significantly once the women had been fully vaccinated.

Dr Cesar Garcia-Diaz, fertility specialist and medical director of IVI London, said it is possible for babies to gain passive immunity to coronavirus through the immunoglobulins in breast milk, which could prevent babies from getting ill.

Dr Cesar told NationalWorld: “Immunoglobulins are antibodies which can protect your baby not only from Covid-19, but all sorts of pathogens.

“If a mother has received one or both doses of the Covid-19 vaccine, she will pass some of the IgG antibodies to her baby through her breast milk. Similarly, if she has had a previous Covid-19 infection, she will pass IgA antibodies to her baby.

“IgG and IgA are different classes of antibody, but both perform a similar job of eliminating pathogens which stops us from getting poorly.”

As babies are born with weakened immune systems, they are particularly susceptible to infection, so any immunity that can be passed on through breast milk would be beneficial.

However, Dr Cesar warned that immunity would only be temporary and should not substitute the routine immunisations recommended for babies once they are eight weeks old.

He added: “In terms of protection against SARS-CoV-2, the exact duration will vary depending on the frequency of feeding and the mother’s own level of immunity.

“While clinical research continues, what we can be sure of is that the longer you breastfeed, the longer your baby will gain at least some protection through the breast milk antibodies.

“For some mothers, this may influence their decision to switch to formula milk, which doesn’t have the same environment-specific antibodies.”

Is breastfeeding safe after Covid-19 vaccination?

Mothers who have been vaccinated against Covid-19 should not be concerned about breastfeeding afterwards, as the vaccines are not thought to be a risk to babies.

The JCVI has recommended that the vaccines can be received while breastfeeding, in line with recommendations from the USA and the World Health Organization (WHO).

Dr Cesar explained: “It is perfectly safe for you and your baby. Likewise, breastfeeding women who are offered their vaccine have nothing to worry about and many leading medical bodies, including the WHO, are now recommending that women who are nursing should receive the vaccine when offered.

“Covid vaccines are not thought to be a risk to a breastfed baby, and the benefits of breast-feeding are numerous.

“From a microbiological and immunological perspective, the benefits of breast milk far exceed those of formulas.

“The complexity of breast milk is difficult to match, containing a rich mix of biologically active components and immunoglobulins which nourish and strengthen a baby’s immune system.

“This isn’t to say that nutrient-filled manufactured formulas won’t boast benefits to young infants. However, no formula is able to pass on the protection of antibodies against infection.”

There is also no need for women to avoid pregnancy after Covid-19 vaccination, as there is no evidence the vaccines have any effect on fertility, or the chances of becoming pregnant.

The vaccines offer pregnant women the best protection against coronavirus, which can be serious in later pregnancy for some women.

Dr Ellen Welch, editorial lead at DAUK, had two doses of the AstraZeneca vaccine while she was pregnant, and said her decision was based on weighing up the risks.

Dr Welch told NationalWorld: “I received both doses of the AstraZeneca vaccine while pregnant and for me, the risks of having long Covid, or being in intensive care with the disease, far outweighed the risks of being vaccinated, but the choice is a personal one.

“The Royal College of Obstetricians and Gynaecologists (RCOG) have useful resources to help women make this decision. But there is no evidence that these vaccinations cause infertility or problems during pregnancy."

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