Table 1

Characteristics of studies with SARS-CoV-2 genome detected in breastmilk

AuthorMaternal characteristicsTime interval between maternal symptoms onset and BM positiveTime interval between maternal symptoms onset and BM negativeType of testInfants of mothers with BM-positive characteristicsComments
Bastug et al 16 # mothers BM RT-PCR positive: 1.
# BM samples tested: 3.
# positive samples: 3.
0 days (asymptomatic)Asymptomatic/no negative samplesGenes tested: S-gene.
Cycle threshold: 28.85–32.28.
Type of feeding: EBM.
Symptoms: no.
Infant positive: yes.
If yes, for how long: NK.
Infant separated from mother at birth and tested negative at birth. Was exposed to EBM on DoL 1. Repeat infant PCR positive at 96 hours. BM continued to test positive on DoL 4 and 5.
Bertino et al 17 # mothers BM RT-PCR positive: 1.
# BM samples tested: 6.
# positive samples: 3.
3 days28 daysGenes tested: ORF1ab, E-gene, N-gene and RdRp.
Cycle threshold: NK.
Type of feeding: BF.
Symptoms: no.
Infant positive: yes.
If yes, for how long: ≤14 days.
Mother symptomatic at time of positive BM test.
Infant only retested 14 days after first test. BM negative on day 15 but positive on day 26 of maternal symptoms. BM negative from day 28 onwards.
Buonsenso et al*18 # mothers BM RT-PCR positive: 1.
# BM samples tested: 10.
9 days13 daysGenes tested: E-gene, N-gene and RdRp.
Cycle threshold: 34.3–38.3.
Type of feeding: EBM.
Symptoms: no.
Infant positive: no.
BM PCR negative on day 11 but positive on day 12 of maternal symptoms. Repeat on day 13 and after remained negative.
Chambers et al 19 # mothers BM RT-PCR positive: 1.
# BM samples tested: 4.
# positive samples: 1.
1 day (collected at the day of symptoms onset)12 daysGenes tested: RdRp and N-genes.
Cycle threshold: NK.
Type of feeding: NK.
Symptoms: yes.
Infant positive: not tested.
Mother symptomatic at time of BM testing.
Infant (9 months) had fever (1 day). BM PCR was positive 14 days before maternal test.
Repeat testing negative. BM also negative by infectivity assay.
Fenizia et al 20 # mothers BM RT-PCR positive: 1.
# BM samples tested: 1.
# positive samples: 1.
NKNKGenes tested: RdRp, E-gene and N-gene.
Cycle threshold: NK.
Type of feeding: NK.
Symptoms: NK.
Infant positive: no.
Groβ et al 11 # mothers BM RT-PCR positive: 1.
# BM samples tested: 7.
# positive samples: 4.
5 days9 daysGenes tested:
N-gene and ORF1b-nsp14.
Cycle threshold: 29.8 (peak, whole milk), 30.4 (peak, skimmed milk).
Type of feeding: BF.
Symptoms: yes.
Infant positive: yes.
If yes, for how long: 15 days.
Mother symptomatic at time of positive BM test.
Repeat BM sample negative (9 days after maternal symptom).
Baby was also positive for RSV.
Hinojosa-Velasco et al 21 # mothers BM RT-PCR positive: 1.
# BM samples tested: 2.
# positive samples: 1.
6 days15 daysGenes tested:
N-gene and ORF1ab
NK.
Type of feeding: BMS and BF.
Symptoms: no.
Infant positive: yes.
If yes, for how long: 13 days.
Kirtsman et al 22 # mothers BM RT-PCR positive: 1
# BM samples tested: 2
# positive samples: 1
4 days9 daysGenes tested: E-gene, N-gene and RdRp.
Cycle threshold: 30.58–32.56.
Type of feeding: BF.
Symptoms: yes
Infant positive: yes
If yes, for how long remained positive: 7 days.
Lugli et al 23 # mothers BM RT-PCR positive: 1.
# BM samples tested: 2.
# positive samples: 2.
6 daysNKGenes tested: E-gene, N-gene and RdRp.
Cycle threshold: 37–38.
Type of feeding: EBM.
Symptoms: no.
Infant positive: no.
First sample taken from EBM expressed at home without precautions, second taken under strict precautions.
Tam et al 24 # mothers BM RT-PCR positive: 1.
# BM samples tested: 7.
# positive samples: 2.
5 days9 days (became positive again at 15 days)Genes tested: E-gene.
Cycle threshold: 20-35.†
Type of feeding: BF.
Symptoms: yes.
Infant positive: yes.
If yes, for how long: 11 days.
4 negative BM samples in between both positive samples. Last sample positive on day 15 of symptoms.
Wu et al 25 # mothers BM RT-PCR positive: 1
# BM samples tested: 2
# positive samples: 1
NKNKGenes tested: NK.
Cycle threshold: NK.
Type of feeding: NK.
Symptoms: no.
Infant positive: no.
Repeat BM sample negative (3 days postmaternal PCR test).
Zhu et al 26 # mothers BM RT-PCR positive: 1.
# BM samples tested: 2.
# positive samples: 2.
3 daysNKGenes tested: ORF1ab and N-gene.
Cycle threshold: 38.2–38.5.
Type of feeding: NK.
Symptoms: NK.
Infant positive: NK.
Mother symptomatic at time of positive BM test.
  • *Information collated from both Buonsenso et al and Costa et al: same cases were reported in two separate papers.

  • †No exact cycle threshold values given.

  • #, number of; BF, breast feeding; BM, breastmilk; DoL, day of life; EBM, expressed breastmilk; E-gene, envelope protein gene; NA, not applicable; N-gene, nucleocapsid protein gene; NK, not known; ORF1b-nsp14, Open Reading Frame 1b-non-structural protein 14; RdRp, RNA dependent RNA polymerase gene; RT-PCR, real time-PCR; S-gene, surface glycoprotein gene.