COVID-19 vaccines mRNA detected into breast milk - now what?
On September 26, a small study was published in the journal JAMA Pediatrics that documents the mRNA of the SARS-CoV-2 Spike (S) protein in the breast milk of 5 out of 11 women after administration of Pfizer or Moderna COVID-19 mRNA vaccines within six months of delivery. The mRNA was present in measurable amounts in all the 5 subjects in extracellular vesicles, and in 3 cases also in total milk. We will briefly discuss how unpredictable this “discovery” could be and what consequences we should draw from it.
COVID-19 mRNA vaccines in breast milk: a surprise?
No, not at all. As a premise, we need to note that already last January a study carried out in Singapore identified intact vaccine mRNA in the milk of 4 mothers (out of 31 studied) 1-3 days after the administration of the vaccine doses of COVID-19 Pfizer [1]. We have nonetheless known for a long time that after the administration of these products both mRNA and the S protein are found in the blood and in many organs and tissues and remain there for an indefinite time, which in most cases is a few weeks but which can be also as long as many months [2-4]. Vaccine-induced S protein circulates in the blood both in free form and inside extracellular vesicles.
Extracellular vesicles - also called exosomes - are lipid bilayer vesicles released by virtually all the cells of the body into the extracellular space. These vesicles are important for intercellular communication and carry proteins, lipids and nucleic acids (DNA, microRNA and messenger RNA). Breast milk is particularly rich in these vesicles, which in recent years have aroused growing interest above all for their content in RNA of maternal origin, which seem to resist the acidic environment and enzymatic hydrolysis of the infant's digestive tract, be absorbed by the intestinal cells and therefore perform physiological functions including: maturation of immune cells, regulation of the immune response, formation of neuronal synapses and also influence on the possible future development of metabolic diseases such as obesity and diabetes [5,6]. It was therefore entirely foreseeable that vaccine mRNA could be found in breast milk.
What are the consequences for the infant?
Short answer: to date no one can say, but the consequences can be manifold. The biggest mistake that could be made is already made by the authors of the study, who begin - discussing their results - with the statement that
“the sporadic presence of traces of COVID-19 vaccine mRNA [in milk] suggests that the 'breastfeeding after vaccination with COVID-19 mRNA is safe”
On the contrary, the only thing that can be said is that - with a high frequency (5 out of 11 in this study, therefore almost 50%) - the infant is exposed to the viral mRNA contained in the vaccines. It would have been necessary to study the consequnces of such exposure a long time ago, and now we can no longer escape the need to examine the issue, but in the meantime some considerations can be made.
First of all, what can be the real exposure of the infant? The JAMA Pediatrics study finds an average of approximately 9 pg / ml of vaccine mRNA in breast milk extracellular vesicles in the first 48 hours after vaccine administration (while the Singapore study measured from 7-8 to 15-16 times higher levels, however without differentiating between milk and extracellular vesicles [1], and we will therefore keep the estimates for the vesicles, which have an excellent probability of being absorbed intact by the infant’s intestine). The volume of milk produced in the 24 hours ranges from a minimum of 500 ml in the first days after childbirth to a maximum of 800-1000 ml six months after delivery. Let’s take 700 ml as the average daily production and we can estimate that the infant will therefore take 700 ml / day x 9 pg / ml x 2 days = 12,600 pg, or 12.6 ng of vaccine mRNA (for each dose: both Pfizer and Moderna are administered in two subsequent doses at a few weeks away from each other). This is an apparently low quantity, especially if we consider that a dose of Pfizer vaccine contains 30 microg of mRNA (that is 500 times more than the estimated exposure in the infant) and a dose of Moderna even 100 microg (over 1,500 times more). One five hundredth of a dose (assuming that it is all absorbed by the infant's intestine, which is quite possible [5,6]), however, may appear in a very different light if we consider the number of vaccine mRNA molecules In the Pfizer product they have been estimated to be about 1.3 × 10e13, or about 13 trillions [7]. One five hundredth is 0.26 x 10e11 molecules, or 26 billion molecules of synthetic mRNA encoding the S protein, an amount which must be compared with the total number of cells in a baby's body, estimated at 1.25 x 10e12. In this way we obtain a copy of mRNA for every 50 cells of the infant, a ratio that makes the transcriptional reprogramming of most of the cells not unlikely, at least, not to mention the possibility of integration into the genome through retroposition, which has been already hypothesized in the adult and so far never excluded through appropriate experimental and clinical studies [4,7].
Furthermore, it cannot be excluded that the passage of vaccine mRNA in the infant's body may result in the endogonous production of the S, eventually resulting in tissue/organ damage, as in adult subjects [2-4]. Finally, it should be considered that the mRNA molecules that circulate outside the cells or even inside the cells but with improper localizations are recognized by the immune system as foreign and trigger inflammatory responses, which contribute to the development of autoimmunity and tissue damage [8].
What the JAMA Pediatrics study doesn't say
The sample of women studied is very small, so the main thing that the study does not say and cannot in any way say is what are the quantities of COVID-19 vaccine mRNA that can pass from mother to infant through milk and for how long. Let us remember that the first study that documented the presence of vaccine S protein in the blood found only low levels in 11 out of 13 people and for only two to four weeks after vaccination [9]. Thereafter, many other studies came to document S protein presence for months, in tens or hundreds of times higher quantities and in tissues and organs damaged by vaccines [2-4].
Second, the authors had the opportunity to verify the presence of vaccine mRNA and the resulting S protein levels in the maternal circulation, but they did not (the Singapore study [1] did it instead, finding vaccine mRNA in the serum of 10/16 (63%) and 10/25 (40%) mothers at 1-3 days after the first dose and at 7-10 days after the second dose). It is plausible at least to ask whether mothers with vaccine mRNA in milk are those in which COVID-19 vaccines pass the most in blood and / or persist for the longest time. We must also ask what happens in those people who have abnormal production of vaccine S protein and consequently experience adverse effects: what levels of mRNA in milk? For how long?
Third, the authors measured vaccine mRNA in milk but not the possible presence of the S protein, which is known to circulate in the body after COVID-19 vaccination both free and within extracellular vesicles [2-4]. In the future, infant exposure could also be measured by directly verifying the presence - for example in the blood - of mRNA or of the S protein, or even the presence of anti-S protein antibodies. In the Singapore study [1], the serum of 5 infants was tested without finding vaccine mRNA or anti-S protein antibodies. However, of the 5 infants tested only one was from mothers with vaccine mRNA in milk and another 3 from mothers with vaccine mRNA in the systemic circulation, which suggests that the last one was from a mother with no vaccine mRNA in blood or milk. Furthermore, the S protein was not looked for in any of the 5 infants.
Finally, another "metacomment", i.e. a comment on the authors' comments on their results. In the last paragraph of the discussion, the authors are keen to reiterate:
"We believe it is safe to breastfeed after maternal vaccination against COVID-19"
And this is their legitimate opinion to date, however, devoid of factual evidence. Then, they continue:
“However, caution is needed with regard to breastfeeding infants less than 6 months of age in the first 48 hours after maternal vaccination until further safety studies are conducted. Furthermore, the potential interference of COVID-19 vaccine mRNA with the immune response to multiple vaccines routinely administered to infants during the first 6 months of age must be considered.”
And these two considerations are completely agreeable, to such an extent that - in the name of any reasonable precautionary principle - it would be convenient, if anyone really wants to get vaccinated, do it away from the period of breastfeeding (and, incidentally, also far from conception and pregnancy) .
Finally, it is on the contrary necessary to radically disagree with the authors' last sentence:
"It is essential that breastfeeding people be included in future vaccination studies to better evaluate the effect of mRNA vaccines on breastfeeding results."
On the contrary, until evidence is available on the safety of COVID-19 mRNA vaccines in breastfeeding, it is essential to avoid their use in this period of life, in order to prevent any damage to the infant, which - precisely on the basis of this study - we can now be sure that it has a high probability of being exposed to the vaccine product.
Side note: there are also few studies on breast milk and SARS-CoV-2, and yet so far it does not seem that the virus can be transmitted with milk, unlike antibodies, which on the contrary can be found in mother’s milk (e.g .: https://pubmed.ncbi.nlm.nih.gov/34417223/ and https://pubmed.ncbi.nlm.nih.gov/32995804/).
References
Yeo, K.T., Chia, W.N., Tan, C.W., Ong, C., Yeo, J.G., Zhang, J., Poh, S.L., Lim, A.J.M., Sim, K.H.Z., Sutamam, N., Chua, C.J.H., Albani, S., Wang, L.F., Chua, M.C. Neutralizitivity and SARS-CoV-2 Vaccine mRNA Persistence in Serum and Breastmilk After BNT162b2 Vaccination in Lactating Women. Front. Immunol. 2022, 12, 783975.
Trougakos, I.P.; Terpos, E.; Alexopoulos, H.; Politou, M.; Paraskevis, D.; Scorilas, A.; Kastritis, E.; Andreakos, E.; Dimopoulos, M.A. Adverse effects of COVID-19 mRNA vaccines: The spike hypothesis. Trends Mol. Med. 2022, 28, 542–554
Cosentino, M.; Marino, F. The spike hypothesis in vaccine-induced adverse effects: Questions and answers. Trends Mol. Med. 2022, 28, 797-799.
Cosentino, M.; Marino, F. Understanding the Pharmacology of COVID-19 mRNA Vaccines: Playing Dice with the Spike? Int. J. Mol. Sci. 2022, 23, 10881.
Jiang, X., You, L., Zhang, Z., Cui, X., Zhong, H., Sun, X., Ji, C., Chi, X. Biological Properties of Milk-Derived Extracellular Vesicles and Their Physiological Functions in Infant. Front. Cell. Dev. Biol. 2021, 9, 693534.
Sanwlani, R., Fonseka, P., Chitti, S.V., Mathivanan, S. Milk-Derived Extracellular Vesicles in Inter-Organism, Cross-Species Communication and Drug Delivery. Proteomes 2020, 8, 11.
Domazet-Lošo, T. mRNA Vaccines: Why Is the Biology of Retroposition Ignored? Genes 2022, 13, 719.
Lai, H.C., Ho, U.Y., James, A., De Souza, P., Roberts, T.L. RNA metabolism and links to inflammatory regulation and disease. Cell. Mol. Life Sci. 2021, 79, 21.
Ogata, A.F.; Cheng, C.A.; Desjardins, M.; Senussi, Y.; Sherman, A.C.; Powell, M.; Novack, L.; Von, S.; Li, X.; Baden, L.R.; et al. Circulating Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccine Antigen Detected in the Plasma of mRNA-1273 Vaccine Recipients. Clin. Infect. Dis. 2022, 74, 715–718.