Many health practitioners in the field of IYCF are raising the question of whether a breastfeeding woman who gets infected with MPOX should CONTINUE or STOP providing breastmilk or breastfeeding. Some guidance has been written by reputable agencies. However, I highly recommend reading the following letter that was written in 2022: Is monkeypox virus transmissible by breastfeeding? Van de Perre P, Molès JP, Rollins N.  Pediatr Allergy Immunol. 2022 Oct;33(10):e13861. doi: 10.1111/pai.13861. PMID: 36282140. It gives more guidance on how to approach the search of the answers to this question. I am aware you might not have access to this article so I have posted the text here below. I recommend to read especially the text in bold. Note, this letter is from 2022 and new guidance might have come up since.

To the Editor,
Since early May 2022, more than 92 non-endemic-prone countries
have been facing an outbreak of monkeypox virus (MPXV) infections. As of 7 September 2022, approximately 53,000 confirmed or suspected cases have been reported to World Health Organization (WHO) and/or European Centers for Disease Control.1 The virus circulating in non-endemic-prone countries is related to the West African Clade. However, the current outbreak shows some differences in clinical features compared to infections in Central and West Africa endemic-prone
areas. Most cases are non-severe with so far, only 18 deaths reported; in contrast, in endemic-prone areas fatality rates are commonly between 3% and 10%. The vast majority of persons affected in this outbreak
are male (and mainly men having sex with men), while in endemic
prone, MPXV countries women are almost equally affected. There
is however concern that many more women of childbearing age
will be affected if the extremely high household transmission rates
as seen in endemic areas are manifest in the present outbreak.
As for many other viral infections, children, pregnant/postpartum
women, and immunodeficient individuals from endemic areas
are at higher risk of developing severe, sometimes fatal forms of
MPXV infection. As observed in smallpox, it is very likely that infants
infected with MPXV present frequently with severe or lethal
forms of the disease. MPXV belongs to the poxviruses family and the Orthopox genus. Orthopoxviruses include 4 viruses of importance for human health: the variola virus responsible for smallpox, the vaccinia virus, the cowpox virus, and the MPXV. There is a 90% genomic homology between variola virus and MPXV. The four human orthopoxviruses share significant characteristics such as a mucocutaneous tropism, animal-to-human, and human-to-human
transmission routes. Known transmission routes involve skin-to-skin,
mucosa-to-skin, skin-to-mucosa direct contacts (especially with lesional and paralesional areas) as well as air droplets respiratory transmission from individuals with MPXV lung shedding and transmission from direct contact with contaminated fomites surfaces.
One of the haunting questions related to MPXV epidemiology is whether the virus can be transmitted through breastfeeding. We recently proposed a Koch's postulate-derived conceptual framework to establish whether viruses are transmitted through breastfeeding based on five criteria.2
1. There is evidence for viral infection in infants receiving breast
milk from infected mothers.
2. Virus, viral antigen, or viral genome is present in the breast milk of
infected mothers.
3. The virus in breast milk is capable of replication.
4. Other relevant transmission routes (e.g., by transplacental, airborne
droplets, arthropod bites, and blood-borne routes) potentially associated
with breastfeeding have been reasonably ruled out.
5. Transmission by breast milk can be reproduced by oral inoculation
in an animal model.
We searched the literature for evidence related to each of these criteria to examine the likelihood of MPXV transmission through breastfeeding. First, we searched the literature for data related to MPXV –where
almost no data was available –then broadened the search to human orthopoxviruses taking into consideration their likely shared routes of transmission. Here, we summarize the available evidence for each criterion:
1. One very likely case of perinatal transmission of MPXV has
been reported in Democratic Republic of Congo (DRC) in 1988
from a woman with likely MPXV infection at 24 weeks of gestation
and her neonate with a generalized skin infection; infant
feeding practices were not, however, described.3 More recently,
symptomatic neonatal infection as a result of mother-to-
child
MPXV infection has been confirmed in DRC.4 Furthermore,
congenital cases of smallpox have been described in India,
but again with no data on infant feeding modalities.5 More
meaningful is the case of vaccinia transmission within a family
following vaccination, even when social distancing practices
were observed, starting from the vaccinated person to his wife
and then to her breastfed baby.6 No attempt was reported
to detect vaccinia virus DNA or viral particles in breast milk
and direct contact of the infant's oral mucosae with lesions
on both maternal areolas remains the more likely route of
transmission.6 This case report supports the current Centers
for Disease Control and Prevention (CDC) recommendations
that a woman who received smallpox vaccine during pregnancy
or breastfeeding should avoid breastfeeding and handling any
baby for at least 3–4
weeks.7 CDC further recommends that
while breast milk supply can be maintained through expression, the expressed milk should be discarded. Criteria 1 is therefore
not fully satisfied.
2. Vaccinia virus DNA and viral particle shedding have been demonstrated
in the milk of infected cow, and this virus has been shown
to be infectious.8 However, similar observations in humans for
any of the human orthopoxviruses are presently lacking. Criteria
2 and 3 are therefore not satisfied either.
3. No data are available that could validate criteria 

4. However, a robust murine model involving non-traumatic inoculation of murine pups with contaminated milk exists that reproduces vaccinia virus transmission by breastfeeding, confirming therefore the fifth criteria.9
Based on the conceptual framework described above and noting
that more than two criteria are undocumented, there is insufficient evidence to infer that transmission of MPXV and/or of human orthopoxviruses takes place thought breastfeeding. More research is needed to determine possible routes and risks of mother-to-child
transmission of human orthopoxviruses through breast milk and breastfeeding. However, even if the occurrence of breast milk transmission of MPX is unknown, there is a high risk of mother-to-child(or child-to-mother) transmission while breastfeeding, due to direct contact with infectious skin or mucocutaneous lesions, including face-to-face, skin-to-skin, mouth-to-mouth, or mouth-to-skin contact. These considerations support the current WHO recommendations on infant feeding in the context of maternal MPXV infection that include case-by-case assessment of transmission risk and, when there is active maternal MPXV infection, the possibility of isolation of the mother from the infant to prevent transmission of the virus.10 Administration of expressed breast milk from a MPXV-infected woman to the infant may be hazardous because of the risk of contamination by mucocutaneous viral shedding during milk collection. 

KEYWORDS
breast milk, breastfeeding, human orthopoxviruses, monkeypox
virus, mother-to-child-transmission
PEER REVIEW
The peer review history for this article is available at https://publo
ns.com/publo n/10.1111/pai.13861.
Philippe Van de Perre1
Jean-Pierre Molès1
Nigel Rollins2

1INSERM, Univ Montpellier, Etablissement Français du Sang, Univ
Antilles, Montpellier, France
2Department of Maternal, Newborn, Child and Adolescent
Health and Ageing, World Health Organization, Geneva,
Switzerland

Correspondence
Philippe Van de Perre, UMR 1058 "Pathogenesis and Control
of Chronic and Emerging Infections" INSERM –Université Montpellier –EFS –Université des Antilles, Inserm ADR Languedoc-Roussillon,
60, rue de Navacelles, 34394 Montpellier Cedex 5, France.
Email: philippe.vande-perre@inserm.fr
Editor: Carmen Riggioni
ORCID
Jean-Pierre Molès https://orcid.org/0000-0002-6863-6350
REFERENCES
1. https://www.who.int/publi catio ns/m/item/multi -count
ry-outbreak-of-monkeypox--external-situation-report--1---6-july-2022
2. Van de Perre P, Moles JP, Nagot N, et al. Revisiting Koch's postulate
to determine the plausibility of viral transmission by human milk.
Pediatr Allergy Immunol. 2021;32:835-842.
3. Jezek Z, Fenner F. Human Monkeypox. Karger; 1988.
4. Mbala PK, Huggins JW, Riu-Rovira T, et al. Maternal and fetal outcomes among pregnant women with human monkeypox infection in
the Democratic Republic of Congo. J Infect Dis. 2017;216:824-828.
5. Fenner F, Henderson DA, Arita I, et al. Smallpox and Its Eradication.
World Health Organization; 1988.
6. Garde V, Harper D, Fairchok MP. Tertiary contact vaccinia in a
breastfeeding infant. JAMA. 2004;291:725-727.
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(MD): National Library of Medicine (US); 2006. Smallpox Vaccine.
[Updated 2020 Jul 20]. Available from: https://www-ncbi-nlm-nih-gov.
proxy.inser mbibl io.inist.fr/books/ NBK50 1099/
8. Moreira Ludolfo de Oliveira T, Maldonado Coelho Guedes MI,
Rehfeld IS, et al. Detection of vaccinia virus in milk: evidence of a
systemic and persistent infection in experimentally infected cows.
Foodborne Pathog Dis. 2015;12:898-903.
9. Rehfeld IS, Maldonado Coelho Guedes MI, Soares Fraiha AL, et al.
Vaccinia virus transmission through experimentally contaminated
milk using a murine model. PLOS One. 2015;10:e0127350.
10. WHO. Clinical management and infection prevention and control of
monkeypox. Interim rapid response guidance 10 June 2022. WHO
reference number: WHO/MPX/Clinical_and_IPC/2022.1.
13993038, 2022, 10, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/pai.13861 by Johns Hopkins University, Wiley Online Library on [30/10/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License