Breast feeding provides passive immunity to babies: maybe another approach to SARS-CoV-2?

One of the many compelling reasons for encouraging a woman to breast feed her baby is to provide the baby with the huge amount of antibodies within the first milk: the colostrum. In fact colostrum is not only packed with beneficial antibodies, but also many hundreds to thousands of distinct bioactive molecules and maternal cells that protect against infection and inflammation, and contribute to immune maturation, organ development and healthy microbial colonization.

So breast feeding is the epitome of provision of passive immunity.

But in obstetric practice there are other examples of providing women and babies with ‘passive immunity’.

Chickenpox (varicella zoster) can make adults very unwell indeed. If a pregnant woman contacts someone with chickenpox and she is uncertain as to whether she has ever had it, and her mother cannot tell her, we can look back at the blood tests done in early pregnancy to see if she has anti-chickenpox antibodies. If she does, she is immune. End of story. If she does not, she is vulnerable and needs protection. We give her a dose of VZIG; Varicella Zoster Immune Globulin. We give her ‘passive immunity’. It was first used in 1978, prepared from patients convalescing from varicella zoster, and shown to prevent or at least ameliorate the disease, as long as it is given within 96 hours of exposure.

Another example is the giving of anti-hepatitis B immunoglobulin to babies born to mothers with high infectivity. The women are identified through screening antenatally and the immunoglobin is sitting in the Delivery Suite fridge to await the babies arrival. ‘Passive immunity’ is followed by a vaccination programme to induce ‘active immunity’.

So I, with my obstetrician’s brain, have been wondering whether this could be applicable to SARS-CoV-2 disease? Could the 'track and trace' (now central to the UK’s COVID strategy) be followed by the giving of immunoglobulin to those traced and found to be particularly vulnerable?

I asked our Infectious Disease advisor, Dr Alistair McGregor, a consultant at Northwick Park Hospital what he thought of this idea and he said this,

‘I have heard that people are looking at passive immunity using convalescent serum but there is only one mention of this on clinicaltrials.gov currently and I don’t know any specifics.

Although this approach has been successful in a variety of viral illnesses (Hepatitis B and Rabies are two more examples), there is a potentially serious concern – antibody dependent enhancement. Basically, some antibody, of the wrong type, can make the infection worse! That’s why the first dengue vaccine was pulled… it protected against one serotype but made the others more dangerous. Happy to be quoted…’

So clearly not the answer I was hoping for, but that by no means says it’s a non-starter. Just that it is an idea which needs to be looked at and worked through carefully in the setting of careful clinical trials.

Back to breast feeding. We know that breast feeding at 6 months declines significantly in areas of social deprivation in the UK. Could this be another factor in the development of metabolic problems in later life and increased vulnerability to severe SARS-CoV-2 disease? One injustice leads to another.