SARS-CoV-2 Viral RNA Found in Breastmilk
by Anne Eglash MD, IBCLC, FABM
As per the systematic review discussed on the last CQW #200, approximately 4% of newborns of mothers positive for SARS-CoV-2 have positive tests in the first few days of life. Despite this low percentage, some professional organizations still express concern about possible transmission of SARS-CoV-2 via breastfeeding.
Several studies have published case reports demonstrating the presence of SARS-CoV-2 RNA particles in breastmilk. The study for this week was conducted in the Los Angeles, CA region, and is among the better-designed studies regarding SARS-CoV-2 RNA in breastmilk. Between March 27 and May 6th, 2020, the researchers collected and analyzed 64 expressed breastmilk samples from 18 mothers who were SARS-CoV-2 positive, with 17/18 having had symptoms of illness. The women were given information on how to collect the breastmilk samples properly to prevent the risk of breastmilk contamination. Among the 64 samples of breastmilk, only one had detectable RNA of the SARS-CoV-2 virus. Thirteen of the 18 children aged neonate-21 months had symptoms of COVID-19, but only 2 needed medical care.
The authors also ran a second and different study. They took breastmilk samples from healthy mothers and spiked them with living SARS-CoV-2 viral particles. They pasteurized the spiked milk samples to find out if the virus would survive pasteurization.
What happened, and what does all of this mean? Well, let's see what you think first:
- It is unclear if the SARS-CoV-2 positive breastmilk sample from the ill mother represented contamination from respiratory secretions, or whether the virus was shed via breastmilk.
- When the SARS-CoV-2 positive breastmilk from the ill mother was cultured, the researchers were unable to grow any living virus.
- Pasteurization of the spiked breastmilk from healthy mothers killed the virus.
- Even before pasteurizing the spiked breastmilk from healthy mothers, the researchers demonstrated that the breastmilk already killed the live virus.
See the Answer
There is no abstract for this article.
The researchers demonstrated that after they spiked the breastmilk from healthy volunteers with SARS-CoV-2 virus, they were able to grow the virus in culture, so breastmilk by itself has not been shown in this study to directly kill the virus. Pasteurization (heating the milk to 62° C for 30 minutes) did kill the virus.
There are a handful of other recently published studies showing SARS-CoV-2 viral RNA in breastmilk of mothers positive for SARS-CoV-2, whether the mothers had symptoms or not. The presence of viral RNA in breastmilk does not necessarily increase the infant’s risk of becoming ill with the virus. The infant is already exposed to mom’s respiratory secretions, which would be the main source of viral exposure. The presence of viral RNA in breastmilk does not mean that there are living viral particles that can infect the infant. The presence of RNA particles just means that there are protein snippets from the virus, but we don’t know that the virus is actually living and infectious. The authors were not able to grow the virus from the ill mothers’ milk that was positive for the viral RNA.
No studies thus far have demonstrated a positive culture, or growth of virus from breastmilk of infected mothers, and no studies have demonstrated that breastfed infants of mothers with who have a + RNA test for SARS-CoV-2 in their breastmilk are more apt to become deathly ill.