Rogers Hixon Ontario Human Milk Bank (Unger, O'Connor); Department of Paediatrics, Sinai Health (Unger); Combined Containment Level 3 Unit (Christie-Holmes, Guvenc, Budylowski, Gray-Owen), Departments of Molecular Genetics (Guvenc, Gray-Owen), Laboratory Medicine and Pathobiology (Mubareka), and Nutritional Sciences (O'Connor), and the Institute of Medical Sciences (Budylowski), University of Toronto; Sunnybrook Research Institute (Mubareka), Toronto, Ont.
CMAJ. 2020 Aug 4;192(31):E871-E874. doi: 10.1503/cmaj.201309. Epub 2020 Jul 9.
Provision of pasteurized donor human milk, as a bridge to mother's own milk, is the standard of care for very low-birth-weight infants in hospital. The aim of this research was to confirm that Holder pasteurization (62.5°C for 30 min) would be sufficient to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in donated human milk samples.
We spiked frozen milk samples from 10 donors to the Rogers Hixon Ontario Human Milk Bank with SARS-CoV-2 to achieve a final concentration of 1 × 10 TCID/mL (50% of the tissue culture infectivity dose per mL). We pasteurized samples using the Holder method or held them at room temperature for 30 minutes and plated serial dilutions on Vero E6 cells for 5 days. We included comparative controls in the study using milk samples from the same donors without addition of virus (pasteurized and unpasteurized) as well as replicates of Vero E6 cells directly inoculated with SARS-CoV-2. We reported cytopathic effects as TCID/mL.
We detected no cytopathic activity in any of the SARS-CoV-2-spiked milk samples that had been pasteurized using the Holder method. In the SARS-CoV-2-spiked milk samples that were not pasteurized but were kept at room temperature for 30 minutes, we observed a reduction in infectious viral titre of about 1 log.
Pasteurization of human milk by the Holder method (62.5°C for 30 min) inactivates SARS-CoV-2. Thus, in the event that donated human milk contains SARS-CoV-2 by transmission through the mammary gland or by contamination, this method of pasteurization renders milk safe for consumption and handling by care providers.
巴氏消毒人乳（62.5°C 加热 30 分钟）作为早产儿从母亲人乳过渡到配方奶的桥梁，是医院极低出生体重儿的标准照护措施。本研究旨在确认巴氏消毒Holder 法（62.5°C 加热 30 分钟）足以有效灭活捐赠人乳样本中的严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）。
我们从 10 位捐赠者的冷冻人乳样本中提取罗氏亨氏安大略省人乳库的样本，用 SARS-CoV-2 进行接种，使样本中病毒终浓度达到 1×10 TCID/mL（每毫升组织培养感染剂量的 50%）。我们采用 Holder 法对样本进行巴氏消毒，或室温放置 30 分钟，然后对连续稀释液进行铺板，在 Vero E6 细胞中培养 5 天。我们将来自同一捐赠者、未经病毒添加的巴氏消毒和未巴氏消毒的人乳样本以及直接接种 SARS-CoV-2 的 Vero E6 细胞作为对照组纳入研究。我们以组织培养感染剂量（TCID）/毫升报告细胞病变效应。
在经过 Holder 法巴氏消毒的 SARS-CoV-2 接种人乳样本中，我们未检测到任何细胞病变效应。在未经巴氏消毒但室温放置 30 分钟的 SARS-CoV-2 接种人乳样本中，我们观察到病毒感染力下降约 1 个对数级。
Holder 法（62.5°C 加热 30 分钟）巴氏消毒人乳可使 SARS-CoV-2 失活。因此，如果捐赠的人乳通过乳腺传播或污染而含有 SARS-CoV-2，这种巴氏消毒方法可使人乳安全用于喂养和护理人员处理。
