ABSTRACT
BackgroundSARS-CoV-2 infections of infants and toddlers are usually mild but can result in life-threatening disease. SARS-CoV-2 RNA been detected in the breast milk of lactating women, but the potential role of breastfeeding in transmission to infants has remained uncertain. MethodsBreast milk specimens were examined for the presence of the virus by RT-PCR and/or culture. Specimens that contained viral RNA (vRNA) were examined for the presence of subgenomic coronavirus RNA (sgRNA), a putative marker of infectivity. Culture methods were used to determine the thermal stability of SARS-CoV-2 in human milk. ResultsBreast milk samples from 110 women (65 confirmed with a SARS-CoV-2 diagnostic test, 36 with symptoms but without tests, and 9 with symptoms but a negative SARS-CoV-2 diagnostic test) were tested by RT-PCR (285 samples) and/or viral culture (160 samples). Although vRNA of SARS-CoV-2 was detected in the milk of 7 of 110 (6%) women with either a confirmed infection or symptomatic illness, and in 6 of 65 (9%) of women with a positive SARS-CoV-2 diagnostic test, virus was not detected in any culture. None of the 7 milk specimens with detectable vRNA contained sgRNA. Notably, when artificially added to human milk in control experiments, infectious SARS-CoV-2 could be cultured despite several freeze-thaw cycles, as occurs in the storage and usage of human milk. ConclusionsSARS-CoV-2 RNA can be found infrequently in the breastmilk of women with recent infection, but we found no evidence that breastmilk contains infectious virus or that breastfeeding represents a risk factor for transmission of infection to infants. Key PointsO_ST_ABSQuestionC_ST_ABSSARS-CoV-2 RNA has been detected in a small number of human milk samples collected from recently infected women. The role of breastfeeding in transmission of the virus to infants has remained uncertain due to the small number of specimens analyzed in any study published thus far. FindingsIn a total study group of 110 women, SARS-CoV-2 RNA was detected in milk from 6 of 65 women (9.2%) with recent confirmed infection. Neither infectious virus nor subgenomic RNA (a marker of virus infectivity) were detected in any of the samples. MeaningWe found no evidence that infectious SARS-CoV-2 is present milk from recently infected women, even if SARS-CoV-2 PCR tests are positive, providing reassurance of the safety of breastfeeding.
ABSTRACT
To The EditorCurrently, the U.S. Centers for Disease Control and Prevention, American Academy of Pediatrics and the World Health Organization advise that women who are infected with SARS-CoV-2 may choose to breastfeed with appropriate protections to prevent transmission of the virus through respiratory droplets.(1) However, the potential for exposure to SARS-CoV-2 through breastfeeding is currently unknown. To date, case reports on breastmilk samples from a total of 24 SARS-CoV-2-infected women have been published.(2-7) Of those, viral RNA was detected in ten breastmilk samples from four women. In some but not all cases, environmental contamination as the source of the virus or retrograde flow from an infected infant could not be ruled out.
